QRP Labs QMX 5W Digi Transceiver Instruction Manual

: June 5, 2024
: QRP Labs

Table of Contents

QMX 5W Digi Transceiver
Product Specifications
Product Usage Instructions
1. Overview of Features
2. Connectors
3. Display Elements
4. Operator Controls
5. Firmware Update Procedure
6. Terminal Applications
- Frequently Asked Questions (FAQ)
Q: Can I use the QMX for PSK31 and phase shift modes?
Q: How many VFOs does the QMX have?

QMX 5W Digi Transceiver

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Product Specifications

Product Name: QMX: QRP Labs Multimode Xcvr (transceiver)
Firmware Version: 1.00_018
Release Date: 01-May-2024
Transceiver Type: QRP (low power)
Frequency Bands: Five-band
Transmitter Output Power: 5W
Microcontroller: STM32F446 (168MHz 32-bit ARM Cortex M4)

Product Usage Instructions

1. Overview of Features

The QMX is a high-performance transceiver kit with a
sophisticated SDR receiver implemented in a microcontroller. Key
features include:

Portability with low current consumption
Standalone CW transceiver or Digimodes modem
Synthesised VFO with rotary encoder tuning
Memory features for frequency presets

2. Connectors

The device comes with various connectors for power, earphones,
paddle, and antenna. Ensure proper connections for optimal
operation.

3. Display Elements

The display elements provide essential information such as
frequency, mode, signal strength, etc. Familiarize yourself with
the display for effective usage.

4. Operator Controls

Understand the functions of different controls like VFO tuning,
memory presets, RIT mode, and CW offset adjustment for seamless
operation.

5. Firmware Update Procedure

Refer to the provided instructions on how to update the firmware
to access new features and improvements.

6. Terminal Applications

Learn how to utilize terminal applications for advanced settings
and configurations of the transceiver.

Frequently Asked Questions (FAQ)

Q: Can I use the QMX for PSK31 and phase shift modes?

A: The QMX is not suitable for PSK31 and phase shift modes until
SSB is implemented in future firmware updates.

Q: How many VFOs does the QMX have?

A: The QMX includes two VFOs – VFO A and VFO B, offering
flexibility in tuning and operation.

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QMX
QMX: QRP Labs Multimode Xcvr (transceiver)
Operating manual, firmware 1.00_018, 01-May-2024

QMX operating manual; firmware 1_00_018

Contents
1. Overview of features…………………………………………………………………………………………………………………………………4
2. Connectors………………………………………………………………………………………………………………………………………………7
3. Display elements…………………………………………………………………………………………………………………………………….10
4. Operator Controls…………………………………………………………………………………………………………………………………..11
4.1 Power On/Off……………………………………………………………………………………………………………………………………12 4.2 Operating mode…………………………………………………………………………………………………………………………………12 4.3 Operating band………………………………………………………………………………………………………………………………….12 4.4 Tune rate………………………………………………………………………………………………………………………………………….12 4.5 Keyer speed………………………………………………………………………………………………………………………………………13 4.6 RIT…………………………………………………………………………………………………………………………………………………… 13 4.7 VFO mode…………………………………………………………………………………………………………………………………………14 4.8 VFO A/B operations……………………………………………………………………………………………………………………………14 4.9 Frequency Presets……………………………………………………………………………………………………………………………..14 4.10 Automated message transmission mode…………………………………………………………………………………………….15 5. Menu System………………………………………………………………………………………………………………………………………….16
5.1 Saving current operating parameters (VFO frequency etc)………………………………………………………………………17 5.2 Types of configuration menu item………………………………………………………………………………………………………..17 5.3 Editing a configuration menu parameter……………………………………………………………………………………………….17 5.4 Editing a LIST parameter……………………………………………………………………………………………………………………..18 5.5 Editing a BOOLEAN parameter…………………………………………………………………………………………………………….18 5.6 Editing a NUMBER parameter………………………………………………………………………………………………………………18 5.7 Editing a TEXT parameter……………………………………………………………………………………………………………………19 5.8 Audio menu………………………………………………………………………………………………………………………………………20 5.9 Frequency presets menu…………………………………………………………………………………………………………………….21 5.10 Messages menu……………………………………………………………………………………………………………………………….22 5.11 Keyer menu…………………………………………………………………………………………………………………………………….23 5.12 CW Decoder menu……………………………………………………………………………………………………………………………26 5.13 Digi interface…………………………………………………………………………………………………………………………………..29 5.14 Beacon menu…………………………………………………………………………………………………………………………………..31 5.15 Display/controls menu………………………………………………………………………………………………………………………37 5.16 Protection menu………………………………………………………………………………………………………………………………43 5.17 System config………………………………………………………………………………………………………………………………….44 5.18 Hardware tests………………………………………………………………………………………………………………………………..50 5.19 Factory Reset…………………………………………………………………………………………………………………………………..51 5.20 Update firmware……………………………………………………………………………………………………………………………..52 5.21 AGC system……………………………………………………………………………………………………………………………………..52 6. Operating QMX on digital modes………………………………………………………………………………………………………………58
7. Firmware Update procedure…………………………………………………………………………………………………………………….65
8. Terminal Applications………………………………………………………………………………………………………………………………69
8.1 PC terminal emulator…………………………………………………………………………………………………………………………69 8.2 Entering terminal applications mode……………………………………………………………………………………………………70 8.3 Exiting terminal applications mode……………………………………………………………………………………………………..70 8.4 Configuration menu……………………………………………………………………………………………………………………………71 8.5 Band configuration……………………………………………………………………………………………………………………………72 8.6 Hardware tests menu………………………………………………………………………………………………………………………..74 8.6.1 Audio filter sweep…………………………………………………………………………………………………………………………..75 8.6.2 RF filter sweep……………………………………………………………………………………………………………………………….76

QMX operating manual; firmware 1_00_018

8.6.3 Image sweep………………………………………………………………………………………………………………………………….80 8.6.4 SWR sweep……………………………………………………………………………………………………………………………………81 8.6.5 LPF sweep………………………………………………………………………………………………………………………………………83 8.6.6 Diagnostics……………………………………………………………………………………………………………………………………..84 8.6.7 GPS viewer…………………………………………………………………………………………………………………………………….86 8.7 PC and CAT menu……………………………………………………………………………………………………………………………..88 8.7.1 System config…………………………………………………………………………………………………………………………………89 8.7.2 Input Analysis………………………………………………………………………………………………………………………………..89 8.7.3 CAT command test………………………………………………………………………………………………………………………….93 8.7.4 CAT monitor…………………………………………………………………………………………………………………………………..98 8.7.5 Log file………………………………………………………………………………………………………………………………………….98 8.8 System menu………………………………………………………………………………………………………………………………….101 8.9 Exit terminal……………………………………………………………………………………………………………………………………101 9. Resources…………………………………………………………………………………………………………………………………………….102
10. Document Revision History…………………………………………………………………………………………………………………..102

QMX operating manual; firmware 1_00_018

Overview of features

QMX is a high performance, five-band multi-mode 5W QRP transceiver kit, which implements a sophisticated SDR receiver in a 168MHz 32-bit ARM Cortex M4 microcontroller (STM32F446). Most of the features are implemented digitally in firmware, and the feature set is continuing to be expanded by ongoing firmware development. Please refer to the later section on planned future functionality. This section provides a brief summary of the features to explore and enjoy.

QMX is highly portable

The small size and very low receive current consumption (as low as 80mA) are key features of QMX, making it an ideal transceiver for portable operations including SOTA and POTA activations.

QMX is a standalone CW transceiver, or a Digimodes modem

You can use QMX on its own, plugging in earphones, power supply, paddle and antenna and operating CW; or, you can connect it to a PC with a single USB-C cable, to provide CAT control and Digital audio to the PC and use it with WSJT-X or other programs for single-tone FSK digital modes (not suitable for PSK31 and phase shift modes until SSB is implemented).

Synthesised VFO with rotary encoder tuning

The VFO is an Si5351A or MS5351M synthesiser chip, configured by the microcontroller. A rotary encoder tunes the VFO, with a variable tuning rate. The radio includes two VFOs, A and B. You can swap from one to the other, copy the contents of the active VFO to the inactive one, or operate Split (Transmit on VFO A, receive on VFO B). There is also a RIT mode offering a receive offset of up to +/- 9,999Hz. The CW offset is also adjustable, and CW-R (sideband swap) mode is supported.

Memory features

There are 16 frequency presets for your favourite operating frequencies. Each frequency preset can be edited in the configuration menu, or loaded/saved into/from the currently operating VFO.

Message mode

The firmware supports storage of 12 messages. Each of these are 50 characters long. A single button click shows the list of messages to send. Message sending can be configured to send just once, or a configurable number of times, or indefinitely repeating. The interval between transmissions is also configurable. The message feature can be useful, for example, for setting up a repeated CQ call with a pause between repeats, during which you can listen for any answers. As soon as you touch the key the message sending is canceled. When message sending is in progress an `M’ character appears near the top right of the display.

CW Keyer

Operation with a Straight key is possible, but the firmware also includes an Iambic keyer, for connection of a paddle. The keyer can be configured to operate in Iambic modes A or B, or Ultimatic mode. The keyer speed is variable via a single button press during operation.

Full or semi break-in

With its solid-state, microcontroller operated transmit/receive switch, the radio can operate cleanly in full break-in “QSK” mode, or if you prefer, semi- break in.

QMX operating manual; firmware 1_00_018

CW Decoder
A CW decoder operates in the microcontroller. This can be useful on air, particularly for newcomers to CW, though it is never anywhere near as good in QRM or weak signal conditions as a good CW operator using the wet-ware between his ears. The decoder has a “Practice” mode too, for you to practice your CW sending without actually generating RF. The decoder can also be used to conveniently enter text in the message storage, or for configuration of any of the other menu items. The decoder can also be switched off if desired.

CW, FSKCW or WSPR Beacon mode
A beacon is included too, and this can be configured to operate in CW, FSKCW or WSPR mode. Owners of the QRP Labs Ultimate-series weak signal mode transmitter kits will be familiar with the operation of WSPR. A GPS module such as the QRP Labs QLG2 GPS receiver kit can optionally be connected to this CW transceiver kit to provide frequency and time discipline, as well as setting the Maidenhead locator (from latitude and longitude) that is encoded in the WSPR message.
S-meter and Battery voltage

An S-meter and battery voltage indicator can be enabled for display on the LCD. These are both configurable to your needs. The battery voltage indicator would be useful if you intend to operate the radio portable on battery power. Battery voltage range warning can be configured and prevention of transmit if out of range.

SWR measurement
Built-in SWR bridge always in-line, continuously measures SWR and power output; these can be configured to show on the display, and a configurable bad-SWR threshold to prevent transmit is available.
Real time clock

A real-time clock can be displayed at the bottom right of the LCD. The time can be set by connecting a GPS receiver such as the QRP Labs QLG2 temporarily to the QMX. When power is disconnected from the QMX, the time is lost and will start at 00:00 at next power-up.

Built-in high performance 48ksps 24-bit USB soundcard
No more audio hum ground loops, or lossy noisy connections; a simple USB cable connection to the PC is all that is required for perfect lossless noise-free, hum-free audio transfer back and forth between QMX and the PC.
CAT control – PC Control commands

The same USB connection also implements a Virtual COM serial port for CAT control commands. This implements a subset of the Kenwood TS-480 command set, with one or two minor additions and exceptions.

It is intended to allow easy operation of the QMX in conjunction with logging software, which typically queries the transceiver to determine operating frequency and other operating parameters. The CAT control interface also supports some basic control features for remote control of QMX if required, and is used by software such as WXJT-X when in digital mode, to control the operating frequency and manage transmit/receive switching.

Rich terminal interface
The Virtual COM serial port connection can be used with a Terminal emulator such as PuTTY, to access a range of configuration, alignment and debug tools within QMX, all delivered over the

QMX operating manual; firmware 1_00_018

serial terminal interface. There are additional serial ports which may be enabled at a later time (firmware enhancement). The complete configuration menu is from the terminal too. Alignment tools include an RF sweep tool which uses the QMX’ own internal signal generator injected into the RF port, to sweep across the band pass filters so you can check whether the performance is optimal and make adjustments if desired.
GPS Interface
The QMX kit has a GPS interface, which is used for calibration, setting the real time clock, and for frequency and time discipline and locator setting during WSPR operation. The GPS interface (1pps and 9600 baud serial data) shares the same pins as the paddle dit and dah signals (necessary due to limited processor I/O). The style of this interface is the same as the earlier QCX-series CW transceiver kits.
The GPS should only be connected during calibration functions or when the beacon is enabled. Connection at other times puts the radio into practice mode (no RF emitted) to protect the PA. You may temporarily connect the GPS while in ordinary operation mode, for the purposes of setting the real time clock.
QRP Labs Firmware Update
A special feature of QRP Labs kits based on STM32-series microcontrollers is the QRP Labs Firmware Update procedure (QFU). In firmware update mode, the radio appears to a USBconnected PC as a USB Flash drive. Updating the firmware is a simple matter of downloading the new firmware file, unzipping it, and copying it into QMX. Firmware updates will always be free. They will deliver performance and functionality enhancements and bug fixes.
ASSEMBLY
Assembly of the transceiver is covered in a separate document.
Note: QMX PCB Rev 2 should be used with firmware 1_00_011 and above.
This document describes operation of QMX, and applies to the firmware version specified. This manual will get you started with QMX, either as a standalone CW transceiver or with your WSJT-X or other digi modes software in minutes.
PLEASE READ THE BASIC ASSEMBLY AND USE INSTRUCTIONS IN THIS MANUAL VERY CAREFULLY BEFORE APPLYING POWER TO THE BOARD!

QMX operating manual; firmware 1_00_018

Connectors

This is the QMX left panel.
Paddle connector The paddle connector is a 3.5mm stereo jack socket and actually has THREE purposes:

Paddle for CW operation

Don’t worry if your paddle has a reversed pinout, or if you connect the dit and dah to a 3.5mm jack plug incorrectly: there is a configuration item in the configuration menu (CW Keyer menu) allowing you to swap the dit and dah in the firmware.
2) GPS interface

Here the 1pps signal from the GPS must be connected to the 3.5mm jack “tip” connection, and the serial data (9600 baud) to the “ring” connection. In QMX these signals are 3.3V logic level; however they are connected to 5V-tolerant I/O pins on the microcontroller so 5V logic level will also work fine. If you are using a GPS module directly, and it has the common 2.8V output logic, this will also work fine.

QMX operating manual; firmware 1_00_018

Note that the QMX cannot supply +5V to the GPS module power supply, and in this regard the GPS interface differs from that of the QRP Labs QCX-series transceivers. So you need to arrange a separate 5V power supply for the QLG2 GPS (for example).
3). Microphone interface In SSB mode, an electret microphone and PTT switch may be connected to the Paddle port.
An internal +2.2K pullup to +3.3V is provided to power electret microphones.
Audio connector The audio output connector is a standard 3.5mm stereo jack socket for connecting 32-ohm earphones or similar. It is not suitable for driving a loudspeaker directly. QMX internally controls the Left and Right channels separately which makes future interesting functionality possible.
DC connector The DC connector is a 2.1mm barrel jack connector, the same as used on other QRP Labs transceiver kits such as QCX+, QCX-mini and QDX. The center pin is positive, the barrel is ground. The supply voltage range for QMX is 6.0 to 12.0V. Maximum power output depends on the supply voltage.

This is the QMX right panel.

QMX operating manual; firmware 1_00_018

RF connector The RF connector is a 50-ohm BNC connector securely bolted to the enclosure. QMX should be used with reasonably well-matched 50-ohm loads. Note that the SWR bridge inside QMX means that there is a DC connection to ground; if you measure using a DVM continuity or ohm-meter between the center pin and ground, you will measure zero ohms. This also means that no additional bleeder resistors are required across a connected resistor, to bleed away static charge buildup.
PTT connector The PTT connector is a 3.5mm stereo jack socket.
There are separate active grounded and active +5V outputs. The conventional way to control external amplifiers is with a grounded PTT. However the QRP Labs 50W PA kit requires a +5V active (Transmit) PTT control signal. So this PTT output connector is capable of providing both styles of PTT connection. The two outputs can be configured individually per band, in the Band Configuration menu. Additionally they may be configured to also be active during receive which may be used to control some external switching for example. Note that the two outputs have 220-ohm resistors in series, to protect internal QMX circuits in the case of short-circuits.
USB connector The USB connector is a USB-C type connector. When connected to a host PC, QMX appears as both a USB sound card (24-bit 110dB 48ksps) and a Virtual COM Serial port used for CAT control and accessing the terminal applications. It therefore effectively emulates a USB hub, with two devices connected (USB sound card, and Serial). Additionally the USB connection is used during bootloader mode, when the QMX appears for firmware update purposes as a USB Flash drive (see later section on firmware update).

QMX operating manual; firmware 1_00_018

Display elements

The kit uses a 2 row, 16 character LCD module, with black text on a yellow/green background. There is a backlight which can be switched off if desired, to save a few mA of current consumption. The display has a large, easy to read font, and is perfectly readable in bright sunlight with no backlight.

The main display layout during ordinary operation (which will be called “main operating mode”) is shown in the following photograph. The display during beacon or message transmission modes, menu editing, alignment etc. differs. The main display elements are as follows:

The receive VFO frequency is always displayed, to 10Hz resolution, at the top left. This may be VFO A or VFO B. In CW mode the nominally 700Hz CW offset is automatically applied. Ordinarily in CW mode, the displayed frequency is also used for transmission.
Tuning rate cursor: the underline appears under the digit which is currently tuned by the rotary encoder. In this example, the tuning rate is 100Hz per click, because the cursor is under the 100Hz digit.
Practice mode: when in CW practice mode (actual transmitting disabled), a P’ is displayed to the right of the frequency on the top row. If the practice mode was caused automatically as a self-protection, by plugging in the GPS, a G’ is displayed. During saved message transmissions, this character is set to `M’ and in ordinary operation, it is blank.
Mode indicator: this single character indicates the current operating mode of the tranceiver; in the example in this photograph it is “CW”.
S-meter: these 3 characters are configurable and display the S-meter/SWR/Power meter. Battery voltage: a battery icon appears to indicate the battery voltage in 7 user-definable
steps: from full to empty and 5 steps in between. It may also be shown or hidden. Transmit VFO: in SPLIT mode, the transmit VFO is displayed on the bottom row of the
display. RIT (Receiver Incremental Tuning): when not in SPLIT mode, and when the RIT is non-
zero, the RIT value is displayed in the bottom left (where the photo shows the VFO B frequency). When RIT is non-zero, and when not in SPLIT mode, the reception frequency is the transmit VFO frequency (which may be VFO A or B) plus the RIT (which may be a negative offset).

QMX operating manual; firmware 1_00_018

Decoded CW: The remaining space on the bottom row is used for displaying the decoded CW text. When RIT is zero, and you are not operating SPLIT or displaying the realtime clock, the whole 16 characters of the bottom row are used for the CW decoder display. When adjusting RIT or keyer speed, only the right section of the screen is used for decoded CW. The CW decoder may be disabled in the Decoder configuration menu.
Real time clock: This can be enabled or disabled, and if enabled, is shown at the bottom right in HH:MM format; it can be set manually or via GPS serial data stream parsing (UT).
4. Operator Controls

This diagram shows the operating controls of the QMX. There are two rotary encoders at left and right, and two push-buttons in the center. The main function of the left rotary encoder is Volume adjustment, and that of the right rotary encoder is Tuning. However, all of the controls have multiple functions, depending on the operating mode, menu editing, etc. The rotary encoders both have a button on their shaft activated by pressing the knobs, and these buttons also have multiple functions.
Most importantly: Press the left knob (VOL) with a single firm long press, to turn on or off the radio!
The two central buttons are used during menu editing primarily for “Select” and “Exit” functions and may be referred to in this manual, as the “select” and “exit” buttons. Select edits a menu item or steps down into a sub-menu; Exit saves an edited menu item or backs up to the parent menu.

QMX operating manual; firmware 1_00_018

It is well worth remembering while you are familiarizing yourself with the operation of the radio, that if you get into any unexpected function or menu you can nearly always press the “Exit” button to cancel and get back to the main operation mode.
Each of the buttons may be pressed once, pressed twice (a double-click) or pressed for a long-hold. This facilitates three different functions for each button.
The laser-etched captions on the QMX front panel act as a reminder of the main functions of the various buttons and controls.

4.1

Power On/Off

The power button is implemented as a long press of the left encoder button. Powering off using this method is recommended, rather than simply disconnecting or powering down your power supply. Not only does it avoid any potential intermittent connections but it also saves the current state of your transceiver (which mode you are in, which band you are on, operating frequency, etc) such that next time you power up, your QMX will be in the same state.

4.2

Operating mode

A single press of the left encoder button cycles through the available operating modes, for example Digital, CW, etc. Operating mode is indicated on the display by an icon on the top row of the display (refer to section 3 above).

4.3

Operating band

A double press of the left encoder button cycles through the available bands on your transceiver. Note that if you find it difficult to cleanly attain the double press operation, you can increase the double-click timeout from the default 300ms. This is a setting in the Display/controls menu. For example, 500ms may be more suitable for you.

4.4

Tune rate

The right-hand rotary encoder tunes the active VFO. The rate of tuning is indicated by the underline cursor. In the example below, the underline cursor is under 100Hz digits. This means the tuning rate is 100Hz. If the cursor was under the comma , this would mean a tune rate of 500 Hz.

The available VFO tuning rates are 1kHz, 500Hz, 100Hz or 10Hz.
A press of the “Rotary” button (in the rotary encoder shaft) causes the tuning rate to change, in the cycle 1kHz -> 500Hz -> 100Hz -> 10Hz -> 1kHz etc.

QMX operating manual; firmware 1_00_018

You can also press-and-hold the rotary encoder shaft button, then turn the rotary encoder to move the cursor to the left or right; this allows selection of steps up to 1MHz; turn the rotary encoder within 0.3 seconds of the button press.

4.5

Keyer speed

During operation of the radio, the keyer speed can be easily adjusted. Click the “Select” button once (also indicated by the text “. Keyer” on the enclosure, and the speed will be displayed on the screen:

A14,006,50 Speed 12

Now you can adjust the speed using the rotary encoder. Press any button to return to the main operating mode. You may operate the radio while the Speed setting is shown. You can also press the rotary encoder shaft button to select sending a stored message, while the Speed adjustment setting is active.
Setting speed to 0 enables “Straight” Key mode regardless of the keyer mode setting; this is useful for quickly being able to key down for antenna tuning purposes. It is much easier than going into the Keyer menu, selecting straight key mode, doing the tune up, then going back into the menu to change to Iambic again. The normal configured keyer mode is automatically restored when you increase the speed above zero.

4.6

RIT

RIT (Receiver Incremental Tuning) allows the receive frequency to be adjusted while the transmit frequency (the displayed VFO frequency) remains the same. It is useful if the other station is offtune, or drifting; other uses include working DX stations who may be listening on a different frequency some kHz away from their transmit frequency.

This radio transceiver allows RIT values from -9,999Hz to +9,999Hz.

RIT can be easily adjusted during ordinary operation by double-clicking the “Select” button (indicated on the enclosure as “.. RIT”:

Now use the rotary encoder to tune the RIT. As you do so, you will hear the RIT immediately applied to the VFO.
The tune rate of the RIT control is again indicated by the underlined digit (here 100Hz). In order to change the tune rate, press and hold the “Rotary” button (in the rotary encoder shaft) and turn the rotary encoder at the same time. You will see the cursor move to the left or right 1 digit at a time. Again, the cursor under the comma indicates 500Hz tuning steps.

QMX operating manual; firmware 1_00_018

To cancel RIT tuning (reset the RIT to zero), press the “Exit” button; this returns to main operating mode and sets the RIT to zero. To return to the main operating mode, press the “Select” button. Now the RIT is displayed under the VFO, for example:
A14,006,50 +0,300
Remember that cancelling RIT mode is easy, just double-click the “Select” button to show the RIT editing, then press the “Exit” button to cancel it (which means, set it to zero). Transmitting is possible while the RIT display is active. You can also press the rotary encoder shaft button to select sending a stored message, while the Speed adjustment setting is active.

4.7

VFO mode

A single press on the “Exit” button changes the active VFO mode. There are two independent VFOs named A and B. There are three VFO modes for using these VFOs:

VFO A is active as transmit and receive VFO; if non-zero, RIT is applied during receive VFO B is active as transmit and receive VFO; if non-zero, RIT is applied during receive Split: VFO A is used for receive, VFO B is used for transmit; RIT is ignored completely

Split mode is often used by DX stations, they transmit and receive on separate frequencies.

4.8

VFO A/B operations

Frequency swap: the contents (frequency) of VFO A and B can be swapped by a single long keypress to the “Exit” button. This can be useful when setting up the VFO frequencies.

Copy VFO A to B: To copy VFO A to B, press the “Exit” button with a long key- press then a single short press. It is similar to tapping a CW `N’ slowly on the “Exit” button.

Copy VFO B to A: To copy VFO A to B, press the “Exit” button with a long key- press then a quick double-press. It is similar to tapping a CW `D’ on the “Exit” button.

4.9

Frequency Presets

There are 16 frequency presets which may be used for storing your favourite frequencies, or for just temporary use, or however you wish!

The presets are labelled 1 to 16, and can be individually edited in the Preset menu (see later). Often it is more convenient to just save them from the current VFO frequency.

QMX operating manual; firmware 1_00_018

To show the list of preset frequencies in normal operation mode, double click the “Exit” button. The display now shows something like this:
A14,027,50 S 1 14,060,00 L
The top row of the display shows the currently active VFO frequency as usual. The bottom row shows a “1” in the 4th character, this is the number of the preset displayed. The next number (here 14,060,00) is the frequency stored in Preset 1. Use the rotary encoder to scroll through the list of presets until you find the one you want. Once you have selected the desired preset, press one of the buttons to Save, Cancel or Load the preset, as follows:
SAVE the current VFO to the selected preset, by pressing the “Select” button CANCEL the preset operation (back to main operating mode), by pressing right rotary
encoder button LOAD the selected preset frequency into the current VFO, by pressing the “Exit” button The “S” in the first character and “L” in the 16th character at the far right, are intended as a reminder of which of the center two buttons to press to Save and to Load.
4.10 Automated message transmission mode
My favourite use of the automated message transmission mode is to send a CQ call repeatedly. If a station answers, you can tap the key to cancel the message sending mode, then transmit. There are 12 message memories. Each one is 50 characters long. In order to send a pre-saved message, press the TUNE knob with a single long press. The first of the saved messages is shown on the screen, for example if a CQ call is stored in Message 1, you may have something like this:
A14,012,00 1. CQ CQ CQ DE G
The bottom row shows the message number at the far left (here it is message 1) followed by the first part of the stored message. If it is blank, that means of course that you have not stored any messages yet! You can now use the TUNE knob to scroll back and forth between the 12 stored messages and find the one which you want to transmit. The message can be transmitted multiple times according to the “Repeats” parameter in the Messages menu (see later description). The interval between the repeated transmissions is also defined in the Messages menu, in the “Interval” parameter.

QMX operating manual; firmware 1_00_018

Once you have selected the message that you want to transmit, press one of the three buttons as follows:
REPEAT: Transmit the message repeatedly by pressing the “Select” button ONCE: Transmit the message only once by pressing the “TUNE” knob button CANCEL: Cancel the messages operation by pressing the “Exit” button
When REPEAT message transmission mode is activated, the number of repeats and the interval between repeats is as specified by the Repeats and Interval parameters in the Messages menu.
The stored message transmission is sent at the currently defined keyer speed.
During the actual stored message transmission, you can immediately cancel the transmission at any time by pressing the “Exit” button or by keying the transmitter with the Morse key or paddle if you are using one.
While the RIT or Speed adjustment modes are active, you may still operate the radio (key the transmitter) and may also press the rotary encoder center shaft button to initiate stored message sending.

5. Menu System
There is an extensive nested menu system with all configuration or operating parameters for the transceiver stored in non-volatile memory (EEPROM). These are editable to control every aspect of the radio’s behaviour. The menus are organised into groups as follows:
Audio Presets Messages CW Keyer CW Decoder Digi interface Beacon Display/Controls Protection System config Hardware tests Factory reset Update firmware
To enter the menu system, give a single long press to the “Select” button. Use the TUNE knob to scroll back and forth between the sub menu groups listed. To enter one of them, press the “Select” button. To return to the main operating mode, press the “Exit” button.
The golden rule while in the menu system, is to press the “Select” button to go in to a deeper menu level or edit an item, and the “Exit” button to back up.
In order to edit a menu item, navigate to the menu item then press the “Select” button to start editing. When you have finished editing the item, press the “Exit” button to save it.
NOTE that changes to configuration parameters in most cases only take effect on the radio, when you leave the menu system and return to the main operating mode. During viewing or editing of menu items, the radio remains in receive mode on the currently selected VFO frequency.

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5.1 Saving current operating parameters (VFO frequency etc)
When you power down QMX by pressing the VOL knob, the display will show “Shut down” briefly before powering down QMX. At this time, various important operating conditions of the transceiver are stored in non-volatile storage (EEPROM) that is retained while the power is off. Next time you switch on QMX, it will power up in the same state that you left it!
The list of items saved is:
Mode (CW, Digi etc) VFO Mode (A, B, Split) VFO A frequency VFO B frequency Tune rate RIT RIT tune rate Volume level (audio gain) Keyer speed
5.2 Types of configuration menu item
There are five types of menu configuration item, and editing these is a little different depending on the type.

LIST: a fixed list of values applicable to that menu item, for example Keyer mode; certain boolean parameters are also equivalent to a list containing only two items (ON/OFF, DISABLED/ENABLED, NO/YES).
NUMBER: a numeric parameter such as a stored frequency preset 3) TEXT: a text configuration item such as a stored message
5.3 Editing a configuration menu parameter
To start editing a parameter, navigate to the desired parameter in the appropriate menu, and then press the “Select” button. When editing is active, you will see a cursor appear under the digit being edited.
For example, here is the message repeat interval setting, containing a small number (1 or 2 digits):

The underline cursor below the 4 indicates that editing is active; turning the TUNE knob will change the parameter value.
When you are finished editing, press the “Exit” button to conclude editing. This saves the parameter in the microcontroller’s EEPROM memory.

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A flashing inverted cursor is also available, you can choose that in the “Cursor Style” parameter in the “Other” menu (see later section). The procedure for editing list, string and number parameters is described below; the above simple example is a short number that is simply adjusted using the TUNE knob; for longer numbers such as frequency, the procedure is different (see following sections).
5.4 Editing a LIST parameter
Editing a list parameter is very simple, it is just a matter of turning the rotary encoder. The display scrolls through the list items. For example, this is the “Keyer mode” parameter in the “CW Keyer” menu:
Note that the editing indicator cursor appears under the leftmost character. Turn the TUNE knob to scroll through the list of possible values. When you are happy with your selection, press either “Select” or “Exit”, to save the change.
5.5 Editing a BOOLEAN parameter
Editing a BOOLEAN parameter (such as YES/NO, ENABLED/DISABLED, ON/OFF) is exactly the same as editing a LIST parameter, except that now the list of items is always restricted to just the two values (representing True/False).
5.6 Editing a NUMBER parameter
When editing a number parameter, the cursor underline appears under the currently edited digit. The cursor starts at the far left (most significant digit). The TUNE knob adjusts the selected digit. The operation is very similar to tuning a VFO in ordinary operation. This example shows editing the beacon frequency, in the beacon menu:

To alter the “tuning rate”, you can either

a) Press the “Select” button to move the cursor to the next digit to the right OR b) Turning the VOL knob allows you to move the cursor left or right.

Editing of the number is concluded, and the number is stored to EEPROM, when either:

a) You press the “Exit” button OR b) You press the “Select” button so many times that the cursor falls off the right hand side

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Yet another way to input numbers, which is a REALLY convenient way, is to use the Morse key and CW decoder! During editing of numeric parameters, the CW decoder is activated but only decodes number characters 0-9. The CW decoder expects well-timed CW, with correct spacing between words and characters. The CW decoder expects you to key in the numbers at near to the configured Keyer speed. If you start keying in straight mode at a much different speed, the CW decoder will adapt to your keying but this may take several characters to “sense” your keying speed, so some characters can be missed. This is not a problem in Iambic keyer (paddle) modes.
When you have keyed in the whole number, the number is automatically saved to EEPROM, which leaves editing mode. Once you are used to editing numeric parameters by keying in CW, it becomes the easiest and fastest way to edit menu parameters.

5.7 Editing a TEXT parameter
An example of a text parameter you may wish to edit is the stored messages. For example, stored message 2 is edited in the Messages menu:

Message 2 CQ CQ CQ DE G0UP

By far the easiest way to edit TEXT parameters is simply to use the CW decoder! As before, it expects well-timed CW, with correct spacing between words and characters when using stright key, and the CW decoder expects you to key in the characters at near to the configured Keyer speed. If you start keying with a straight key at a much different speed, the CW decoder will adapt to your keying but this may take several characters to “sense” your keying speed, so some characters can be missed. The problem does not occur with Iambic (paddle) keying modes.

Editing of the parameter is concluded either when you press the “Exit” button, or when no more characters are available for editing; for example, if you filled up the chosen Message memory.

It is also possible to edit a text parameter entirely with the buttons and rotary encoder, though this is usually a slower way to edit text parameters. Owners of the QRP Labs Ultimate3S (or earlier) QRSS/WSPR transmitter kits will already be familiar with this style of editing text.

The text parameter supports all of the characters which the Message keyer can encode, which is the same as the CW decoder can decode. Specifically, A to Z, 0 to 9, Space, then punctuation characters / = ? . , Note = is the break character, CW -…- (dah dit dit dit dah).

The following characters/symbols have special functions.

Insert: Use this symbol to insert a character in the text. Find this character using the rotary encoder, then press the “Select” button to activate it. All the characters to the right of the cursor position are shifted right one position, including the character which was originally in the current position.

Backspace (delete): If you select this character as the current character using the rotary encoder, then when you press the “Select” button, the current character is deleted and the cursor moves back left one position.

Delete all: If selected as the current character, pressing the “Select” button has the effect of deleting the entire message, starting again at the left of the screen. There is no “undo”, so use with caution!

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Enter Right (finished): The behaviour of this symbol is the same as Enter, except that it preserves all the text, including the text to the right of the cursor. It simply saves the whole line. Enter (finished): If selected as the current character using the rotary encoder, pressing the “Select” button is used to finish editing the setting. The setting is saved, and you leave editing mode. Note that the text that is saved is only the text to the left of the Enter symbol. If you select this symbol and press the “Select” button when you are not at the furthest right position of the message, then everything right of your position is deleted. You can also move the cursor backwards and forwards within the text being edited, by turning the VOL knob. This moves the cursor position within the text parameter.
5.8 Audio menu
AGC settings The AGC settings sub-menu appears as the first item in the Audio menu. Since the AGC settings are a detailed topic, they will be discussed in a later section of this manual.
Other audio parameters:

Volume step 0.5dB
Each click of the main volume control knob increases or decreases the receiver volume by this step. Available values are 0.25dB, 0.5dB, 1dB, 2dB and 4dB.

Audio atten. 0dB
An additional audio attenuator exists in the audio output path, which may be set to one of: 0, 20, 40, 60, 80 or 100dB. The default is 0dB. This may be used to reduce the gain if you are using sensitive headphones for example, and you find that the minimum volume setting is still too loud.

Mute at min. vol NO
When YES, the audio is completely muted at minimum volume.
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Sidetone volume 59
Sets the sidetone volume. When editing the menu on the QMX itself, you are able to close the key contacts (dit or dah) normally but no RF transmission will occur. You can use this feature to check how the sidetone sounds and select a comfortable volume.

Sidetone abs/rel Relative
This setting determines how the Sidetone volume setting is applied. There are two possible values as follows:
· Relative: the sidetone level is set by the “Sidetone volume” parameter, however it is also affected by the main volume control. As you increase the volume for example, by turning the volume control clockwise, the received signals AND the sidetone volume both increase by the same amount.
· Absolute: the sidetone level is fixed by the “Sidetone volume” parameter, regardless of the setting of the main volume control. If you adjust the main volume, it only changes the sound level of the received signals, the sidetone level remains the same.

Suppress thump NO
Set this to YES, to avoid the TXRX thump in the earphones on full QSK CW. In future firmware versions this setting will be removed and thump suppression will always be active.

5.9 Frequency presets menu
There are 16 frequency presets, labelled 1 to 16. This example shows Preset 5:
Preset 5 14,020,000
All of the Preset menu items are NUMBER types. Refer to the “Editing a NUMBER parameter” section above for instructions on how to edit a NUMBER parameter. It is also convenient to load the current VFO into the preset memories as described in the section above titled “Frequency Presets”.

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5.10 Messages menu
There are 14 configuration items in the Messages menu. The first 12 are the stored messages, each of which is up to 50 characters long. These are followed by the Interval and Repeats parameters. The stored message presets are 50 characters long, and edited as per the “text” editing procedure described previously.
Message 1

Turn the TUNE knob to select the Message from 1 to 12 which you wish to edit, then press the “Select” button. Now you can edit the message text in one of two ways:

Choose each character individually from the list, using the TUNE knob to select the desired character; when you have chosen the correct character, press the “Select” button to move to the next character, or you can use the VOL knob to move the cursor left or right. This process is described in more detail in the preceding section on editing text parameters.
Key in the desired text on the straight Morse key on the board, or using your external paddle. The CW decoder must be enabled for menu editing (see “Enable edit” parameter).
PROSIGNS: Morse prosigns are typically pairs of concatenated characters which are sounded without a gap. The most common examples are AR, KN and SK (also known as VA). You can include any such prosigns in your saved messages. To specify a prosign, use the character. When the character is included in a saved message, it indicates that the following two characters are to be sent without a gap between them. You would typically use AR, KN and SK but there is nothing to stop you concatenating any pair of characters, to form other prosigns less commonly used.
Interval 14
The Interval is a NUMBER parameter that specifies the interval in seconds, between repeated transmission of a stored message (if repeats are configured: see next parameter).

Repeats 3
The Repeats parameter specifies how many times the message transmission will be repeated, in the repeat transmission mode. The Repeat parameter is a number from 0 to 99; in the case it is set to zero, the Message transmission continues indefinitely.

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5.11 Keyer menu
The Keyer menu contains a number of configuration parameters relating to the CW keyer, which are described below.

Keyer mode Iambic A
The mode of the CW keyer function in the firmware. Possible modes are: Straight IAMBIC A IAMBIC B Ultimatic
If you wish to use a traditional up/down Morse key, these are called “straight” keys and you should select the “Straight” mode. If you wish to use a modern paddle then select the desired operating mode e.g. IAMBIC A.
Keyer swap NO
This is a BOOLEAN parameter which lets you swap the “dit” and “dah” connections in software, if you find that your paddle is reversed.

Keyer Weight 500
Ordinarily Morse dit and dah durations have a 1:3 ratio. The space between symbols is equivalent to 1 dit, between characters 3 dit lengths, and between words 7 dit lengths. This is standard Morse timing. However, some people may wish to alter this, for various reasons.
The Keyer Weight parameter allows variation of the ratios. The value has three digits. The default value of 500 corresponds to 50.0%. This means the “duty cycle” of a stream of dits is exactly 50%. The key-down dit length is therefore the same as the key-up inter-symbol pause.
If the weight is increased from the default 50.0%, then the key-down “dit” is made longer. A “dah” is lengthened by the SAME amount. The corresponding inter-symbol (or character, or word) gap is shortened by the same amount. The additional time spent on the key-down is therefore taken from the key-up period. The keyer speed is unchanged by altering the weight parameter.
As an example: suppose you want to make your Morse sound “harder” by shortening the dits and dahs. You could set the parameter to 450, which means 45.0%.

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The parameter range is 050 to 950 (5% to 95%) though you would not normally ever need to go anywhere near these unreasonable limits. In the event that you enter a value outside this range, the firmware automatically applies these limits to the actually used parameter.

Auto Space OFF
Auto-spacing means that the pause between CW characters is forced to be 3 dit lengths (more or less, if you have CW weighting configured, see above).
The majority of keyers do not implement auto-spacing. You use the paddle to send your dits and dahs making up the Morse character you wish to send. As soon as you next press the paddle, the next character is started. The keyer forces correct 1:3 ratio of dits and dahs and inter-symbol spacing, but it does not force you to wait for the correct duration of 3 dits between transmitted characters.
Some keyers do implement automatic character spacing, such as the old (1973) Accu-Keyer design by James WB4VVF see https://inza.files.wordpress.com/2011/01 /accu-keyer.pdf .
This configuration therefore allows you to switch on automatic character spacing if you wish. In this case, if you press a paddle too SOON, before the 3 dit durations have elapsed after the last character completed, the keyer will wait until the correct time to start the next character.
In the even that you press the paddle too LATE, there is nothing the keyer can do to travel back in time and force it to 3 dit lengths for you. You might have intended an inter-word space, for example. So pressing the paddle too late cannot be corrected.

Semi QSK OFF
This setting defines the break-in (QSK) behaviour of the radio. Two settings are possible:
OFF: indicates Full QSK mode. After the delay time for RF envelope shaping, the Transmit/Receive switch is set to “Receive” shortly after key-up. In this way, you will hear the other station (or any QRM, QRN etc) transmitting in between the dits and dahs of your own transmissions. Many experienced operators like to be able to have a feel for what is happening on the band, in between their key-downs. In some ways you feel like you are listening to your own sidetone audio as just another signal on the band, and you can still hear other signals too.
ON: Semi-QSK mode is enabled. After key-up, there is a delay before the Transmit/Receive switch is set back to “Receive” mode. The receiver is therefore kept muted during your whole CW transmission, not listening to the band in between your transmitted symbols. Many operators prefer to avoid the distraction of hearing the band between their dits and dahs. In Semi-QSK mode the Transmit/Receive switch is set back to “Receive” only after a suitable delay (of 8 dit lengths), long enough to occur only at the end of the transmission.

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Practice mode OFF
Normally you would leave Practice mode switched OFF. However if you want to practice sending CW, and see if the CW Decoder can decode you, then you can switch Practice mode to ON. In practice mode, the radio does everything it normally would, except that it never sends any RF power to the antenna!
During practice mode, a `P’ is shown in the display to the right of the frequency on the top row.

CW offset 700
Sets the CW reception offset. The CW filter in QMX is a 300Hz wide filter centered on 700Hz. By default the CW offset is therefore 700Hz, to place the received signal in the middle of the CW filter. Operators who prefer a lower or higher pitch may adjust the CW offset in this setting. Valid values are 600-800Hz, so as to stay within the bandwidth of the CW filter.

Sidetone frq 700
This NUMBER parameter allows you to change the Sidetone frequency if you wish. Sidetone is the audio tone which is generated by the microcontroller on key- down and injected into the audio signal path. Sidetone is ONLY an operator convenience to let you hear your keyed signal, and has no impact at all on the transmitted RF amplitude or frequency.

Sidetone vol 099
You can use this parameter to reduce the volume of the sidetone audio. See full description in the “Audio” menu above, where this parameter also appears.

Sidetone abs/rel Relative

Controls whether the sidetone is applied absolutely or relative to the main volume control level. See full description in the “Audio” menu above, where this parameter also appears.

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Strght mode Both
Available settings are “tip”, “ring” and “both”. This controls the action of a key plugged into the key jack during Straight Key mode only. It is inherited from the QCX-series transceivers; if a 3.5mm mono plug was used with the QCX+, the longer ground barrel shorted the ring to ground causing continuous keying. This configuration menu is the solution to that problem. If you are using a mono 3.5mm plug with your straight key, then set this configuration to “Tip” so that the ring connection (available only on stereo plugs) is ignored.
GPS protection ENABLED
If QMX detects a GPS receiver has been plugged into the paddle port, it will automatically set up a temporary “Practice mode” (if practice mode is not already enabled) so that the radio is not continuously keyed by the incoming GPS serial data and 1pps. A G’ character appears in the display to the right of the frequency on the top row (where theP’ would be shown in Practice mode). You can disable this automatic protection feature by setting the GPS protection mode parameter to DISABLE.
5.12 CW Decoder menu
The Decoder menu contains a number of configuration parameters relating to the CW decoder, which are described below. Some of these parameters control some aspects of the decoder behaviour. Some constructors may find it interesting to experiment with these settings and see if you can improve the performance of the CW decoder in your specific circumstances. For example, some stations may experience more noise interference than others, depending on your location etc. Note that the Decoder is able to decode the Morse prosign symbols AR, KN and SK/VA. When shown in the decoded text section of the display, they appear as two characters, for example AR. When using the keyer to enter text into message menus, the two characters are prefixed by the _ character to indicate to the QMX that when replaying the message, the following two characters should be strung together without any gap.

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Noise blnk. 10
This parameter defines the duration of the noise blanker in milliseconds. The microcontroller’s 24bit stereo I Q ADC samples audio at 48ksps (thousand samples per second). Blocks of 32 samples are analysed by an implementation of the Goertzel algorithm (kind of a single bucket of a Fourier Transform), which results in a digital filter bandwidth of 250Hz. In other words, it results in a measurement of the amplitude 250 times per second, i.e. once every 4 milliseconds. The amplitude is analysed by logic which compares it to a threshold amplitude to decide if a tone has been detected or not. Impulse noise that generates shorter pulses than the noise blanker parameter, is ignored.
If the noise blanking period is too short, then noise impulses will not be blanked effectively. On the other hand, if the noise blanking period is too long, then it will impair the decoder’s ability to decode high speed Morse. For example, 24wpm Morse has dits lasting 50 milliseconds.

Speed avg. 07
The duration of dits and dahs is measured in order to define a threshold at which to define a tone burst as a dit or a dah, and whether to define no tone at all as an inter-symbol, inter-character or inter-word gap. The measurement of this timing is implemented via an exponential moving average, whose averaging duration is determined by this parameter (the weight of each new measured symbol in the accumulated average).
If the exponential moving average is too fast (the parameter value is too low) then noise etc will throw off the timing averages too easily. If the exponential moving average is too slow (the parameter value is too high), then too many characters of the other station’s transmission will be missed, while we try to adjust to the speed of his sending. This can be particularly offensive in some contest or pileup situations where exchanges are very short.

Ampl. Avg. 60

The decoder maintains an amplitude threshold, which it uses to decide whether a tone is detected or not. The level of this threshold must be varied automatically in order to cope with stations having a wide range of different signal strengths. Other perils may include QSB (signal fading) of the station you are listening to. The amplitude threshold is implemented via an exponential moving average. The weighting of each new sample (every 4ms) added to the accumulated exponential moving average value is the reciprocal of this parameter.
If the exponential moving average is too fast (the parameter value is too low) then noise etc will too easily throw off the amplitude threshold and it may take time to recover to its proper level. If

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the exponential moving average is too slow (the parameter value is too high), then it may take too long to adjust to the received station’s amplitude, resulting in missed characters while the decoder slowly adjusts itself. It would also be too slow to automatically respond to QSB (signal fading).
Enable Rx YES
An experienced CW operator may well dislike the CW decoder scrolling across the display all the time. With this setting you can switch “Enable RX decode” to NO and the receiver decoding is disabled.
Enable Tx YES
With this setting you can switch “Enable TX decode” to NO and the transmit decoding is disabled. When this setting is YES, the CW decoder will decode your own keying and display it on the screen while you transmit. For an experienced CW operator that may be distracting too!
Enable edit YES
This parameter enables CW decoding while editing. When YES, anything you key during editing of NUMBER or TEXT type configuration parameters, edits the parameter. This is a really useful feature that makes it very easy to enter frequencies or stored messages, for example.
SK or VA VA
This parameter only controls whether the SK/VA prosign character, when decoded, is shown as “SK” (this setting is OFF) or displayed as “VA” (this setting is ON). The proper definition of this prosign character is somewhat disputed; some people believe passionately that it is SK, others that it is VA. For the sake of universal harmony this parameter therefore lets you choose your preference.

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5.13 Digi interface
This menu contains settings relevant to the PC/QMX interface during Digital mode operations.

VOX OFF
If you want to use VOX (Voice Operated Transmission) then set this parameter to ON. Any incoming audio from the PC will then operate the Transmit/Receive switch and be transmitted. When the audio stops, QMX will switch back to Receive automatically. The problem with this is that any system sounds on your PC, if the PC is configured to deliver these to the QMX USB sound card, will operate the transmitter and be transmitted.
The default setting “OFF” requires a CAT command from the PC host application (WSJT-X for example) in order to enable the transmitter. This is discussed in this manual in the section on setting up WSJT-X for QMX
If you wish to use software that does not support CAT Transmit/Receive switching, this may be one reason why you would want to enable VOX.
If using VOX, you will also need to disable the CAT timeout feature (see below).
The Voice Operated Transmit (VOX) function is not normally used. Normally you will wish to connect WSJT-X (for example) via CAT to the QMX Virtual COM serial port.

Rise threshold 80
This is a percentage signal level of maximum, above which the transmitter will be keyed down (switched on). Its purpose is to ignore very low amplitude audio signals at the start of a raised cosine keying envelope, whose audio tone could be decoded inaccurately due to quantization error. This is discussed further in the Design section of this manual in the Audio Frequency Analysis section. The default value of 80% should be fine for all purposes. The value should not be set too close to 99%, since higher frequency audio where the number of samples per cycle is small, may not contain a value sufficient to trigger this threshold in every cycle.

Fall threshold 60

This is a percentage signal level of maximum, below which the transmitter will be keyed up (switched off). Its purpose is to ignore very low amplitude audio signals at the end of a raised cosine keying envelope, whose audio tone could be decoded inaccurately due to quantization error. This is discussed further in the Design section of this manual in the Audio Frequency

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Analysis section. The default value of 60% should be fine for all purposes. The value should not exceed (or be close to) the Rise threshold parameter, otherwise the transmitter will be repeatedly keyed on and off falsely.
Minimum cycles 01
This parameter specifies the minimum number of audio cycles to use, in the measurement of audio cycle period, for audio frequency calculation. This parameter is used in conjunction with the Minimum samples parameter: both conditions must be satisfied in order for an audio frequency measurement to be completed. This parameter is discussed further in the Design section of this manual in the Audio Frequency Analysis section. The default value of 1 should be fine for all purposes.
Minimum samples 480
This parameter specifies the minimum number of audio samples to use, in the measurement of audio cycle period, for audio frequency calculation. This parameter is used in conjunction with the QMX operating manual Minimum samples parameter: both conditions must be satisfied in order for an audio frequency measurement to be completed. This parameter is discussed further in the Design section of this manual in the Audio Frequency Analysis section. The default value of 480 should be fine for all purposes. Bearing in mind that there are 48,000 audio samples per second, a value of 480 specifies a minimum 0.01 second audio measurement period. In other words, there will be 100 measurements of the audio frequency, per second, in this default configuration. This is sufficient to ensure that high audio frequencies are measured accurately. In the unlikely event that frequencies below 100Hz need to be measured, the “Minimum cycles” value (1) will ensure that a longer measurement period is used, to measure one cycle.
Discard samples 1
This parameter specifies the number of audio cycles (zero crossings) which are ignored, when audio is first detected. The reason for this parameter is that in conjunction with the “Rise threshold” parameter, it can be seen that the first audio cycle after the threshold is passed, is not a complete cycle. The following zero crossing therefore needs to be discarded because its period measurement will be too short. The default value of 1 should be fine for all purposes.

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IQ mode DISABLED
When IQ mode is enabled, the raw I and Q channels from the ADC are fed to the USB soundcard directly, without any demodulation. This is suitable for people wishing to experiment with using QMX as an SDR front end, with PC SDR software to demodulate I and Q channels. IQ Mode is not suitable for use with WSJT-X and other Digi mode programs.

TX shift thrshld 0
Specifies the number of milliHz that the detected audio signal during transmit must change before the Si5351A is reconfigured to transmit the new value. It can normally be left at zero. For modes like FT8 it doesn’t make any difference. For modes such as FST4W with very slow transmit cycles and very narrow tone spacing, this parameter should be lower or zero if possible.

5.14 Beacon menu
The beacon function is an added bonus feature of this QRP Labs transceiver kit! We already have extensive experience for several years, developing the Ultimate-series QRSS/WSPR transmitter kits (current incarnation, the Utimate3S). These have a huge array of functionality and modes including CW, QRSS, DFCW, FSKCW, Hellscreiber (full speed and slow FSK), WSPR, JT9, JT65, ISCAT, Opera and PI4. The vast majority of people use the Ultimate3S kit for WSPR operation. Since it costs nothing (no extra hardware, at least) to add this functionality to the QMX transceiver, why not! Let’s do it!
The CW transceiver beacon function therefore contains a simplified WSPR implementation which can transmit standard WSPR messages. It also has a GPS interface for discipline of time, frequency and Maidenhead locator. The implementation of course does not have the full range of flexibility and functionality as the Ultimate3S kit.
WARNING: WSPR transmissions operate a continuous 100% key-down duty-cycle for almost 2 minutes. You should check carefully whether the BS170’s get too hot during this period. WSPR is much more demanding on the PA transistors than CW or other Digimodes such as FT8 which have alternating Transmit and Receive cycles.
The beacon function can also operate a CW or FSKCW (slow narrowband) beacon.
Weak Signal Propagation Reporter
WSPR stands for Weak Signal Propagation Reporter. It is digital message format filled with clever forward error correction. The message consists of three parts: the operator’s callsign, Maidenhead locator (4-character, e.g. IO90) and two digits specifying the power. At the receiving station, messages are decoded and uploaded to a central internet database. At any time you can go to

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WSPRnet http://wsprnet.org and click on the map, enter your callsign (and other filters if you wish), and see a map of where your signal is being heard.
You could also undertake more in-depth propagation studies by downloading the database of reception reports.
The WSPR message is encoded into a set of 162 symbols, each may be 0, 1, 2 or 3, using a compressed data format with forward error correction. The symbols are transmitted as tones, each tone separated by 12,000 / 8,192 Hz i.e. approximately 1.46Hz. The duration of each symbol is the reciprocal of the tone spacing, which is approximately 0.683 seconds. WSPR messages take about 110.6 seconds to transmit, and always start at even minutes past the hour.
Due to the very narrow 6Hz bandwidth of the transmission, and the clever forward error correction, WSPR signals can propagate globally even with a fraction of a watt.
In WSPR, timing is critical, so when using WSPR you must set the time configuration parameter as exactly as possible. Be sure to keep the editing cursor under the rightmost (1-minute) digit of the time parameter, watch your clock until the seconds turn over to 00, and then press the “Select” button. This will ensure the seconds are in sync with your real clock time. If careful attention is given to setting the frequency and the real time clock, then successful WSPR reports will be obtained. Of course these things are easier if you are using a GPS module: the Maidenhead locator will be calculated from the received latitude and longitude, and the time decoded nicely from the GPS serial data stream.
The microcontroller in this kit takes care of the WSPR message encoding algorithm, without any assistance from a PC host computer. It also calculates the tone spacing and symbol duration.
In between message transmissions, the display will show instead just a clock (see below), while we wait patiently for the next WSPR transmission to begin, according to the settings of the configuration parameters Frame and Start. This is useful for checking that the time on your kit is accurately set. The display also shows the minute at which the next frame will start transmitting. In the example below, the time is 14:55:31 UT and the next frame will start at 14:56:01.
14,097,140 WSPR 14:55:31 < 56
When a GPS unit is connected, the firmware automatically uses the 1 pulse-per- second signal to measure the transmit frequency and compensate for any inaccuracy due to calibration error or frequency drift due to temperature. The serial data stream from the GPS is used to set the real time clock (for syncing the WSPR transmission timing). The Maidenhead locator is computed from the latitude and longitude information parsed from the GPS serial data.
A WSPR transmission takes 1 minute and 52 seconds. The GPS time and location data is parsed from the GPS serial data stream at the END of every WSPR transmission. You should not configure your kit for continuous WSPR transmissions in every 2-minute WSPR slot (Frame parameter is 2), which is considered very antisocial to fellow WSPR operators.
A GPS receiver isn’t essential for WSPR operation but it is highly recommended because it makes operation more accurate, easy and fun.
During the actual WSPR message transmission, the display shows something like this:

QMX operating manual; firmware 1_00_018

14,097,140 122 2 G0UPL IO90 37

The elements of this display are explained as follows:

14,097,140 Transmission frequency (tone 0)

122

Current symbol is 122 (of 162 symbols making up a WSPR transmission)

Current tone being transmitted (one of 0, 1, 2 or 3)

G0UPL

Callsign encoded into the transmission

IO90

5-character Maidenhead Locator square, encoded into the transmission

Power in dBm, encoded into the transmission

On a PC spectrum display such as the Argo software http://www.weaksignals.com/ WSPR messages look something like the screenshot below when received locally (or usually worse, because you probably are over-driving your receiver when receiving your own signal!):

WSPR decoding takes place in the WSPR program by K1JT (see http://physics.princeton.edu/pulsar/K1JT/wspr.html ). Below is a screenshot showing the WSPR 2.0 screen following reception of a few transmissions (output frequency = 1,500Hz, Frame = 02, Start = 00).

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A number of other software packages are now also capable of decoding WSPR transmissions, the most popular of which is WSJT-X.
NOTE: the GPS interface is connected in parallel in the circuit, with the paddle. Therefore, you should NOT have the GPS connected, while operating the radio as an ordinary CW transceiver. If you do, the GPS serial data and 1pps will key the transmitter! Disconnect the GPS before using the radio as a CW transceiver.
The following sections describe the configuration parameters in the Beacon menu.

Mode OFF
This parameter determines the transmission mode during beacon operation. There are four possible beacon modes:
OFF: The beacon mode is off, the transceiver is in ordinary manual operating mode
CW: the kit simply sends stored message 1 repeatedly, according to the configured Keyer speed, and with message start timing determined by the Frame and Start parameters (see next sections).
WSPR: the kit sends WSPR according to the configuration parameters in the following sections.
FSKCW: the kit sends stored message 1 repeatedly in slow FSK CW, where “key- down” is shifted up 4Hz and “key-up” is transmitted at the carrier frequency. The symbol duration is controlled by the keyer speed, interpreted as the number of seconds for a CW “dit”.
If beacon mode is enabled (not OFF), the radio starts operating in beacon mode on power-up.
While beacon mode is operational, it can be canceled immediately at any time by pressing the “exit” button. Remember that you should not have a GPS connected, when in ordinary CW transceiver mode it would key the transmitter since the GPS and paddle share the same processor I/O signals though if GPS protection is on (See Keyer menu), the radio will automatically enter a “Practice mode” where no RF is produced.
Beacon mode is entered upon leaving the configuration menu system, if the beacon is enabled by having this parameter set to a value other than OFF.

Frequency 14,097,140

This parameter determines the transmission frequency during beacon operation. In WSPR mode, this is the frequency of tone 0.
It should be noted that the WSPR sub-bands on the bands are only 200Hz wide. You also need to specify the correct frequency so that your transmission is inside the appropriate 200Hz sub-band. QMX uses a 25MHz TCXO reference which is normally within a few Hz, so accuracy of the transmission frequency is not normally an issue, even with no calibration.

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Note that these are the actual transmission frequencies, there is no CW offset, no RIT, no other modifications. The specified frequency is also DIFFERENT from the “USB dial frequency” specified at WSPRnet http://wsprnet.org the “USB dial frequency” is 1500Hz lower than the actual transmit frequency, so that the decoded audio is at 1500Hz.

Therefore, ensure that for WPSR transmissions, you choose a frequency in one of the WSPR subbands according to the following table (applicable only to the bands available in your QMX version):

80m: 60m: 40m: 30m: 20m: 17m: 15m: 12m: 10m:

3.570000 3.570200 5.288600 5.288800 7.040000 7.040200 10.140100 10.140300 14.097000 14.097200 18.106000 18.106200 21.096000 21.096200 24.926000 24.926200 28.126000 28.126200

Frame 10
This parameter defines the repetition rate of the WSPR transmission. In the example shown here, Frame 10, this means that the WSPR message will be transmitted once every 10 minutes. Transmission in every 2 minute WSPR slot is considered anti-social. 10 minute repeat transmissions is usually considered normal.

Start 4
If everybody transmits with 10 minute repetition rate starting on the hour, then there will be bursts of activity every 10 minutes where everyone is transmitting at once, and the potential for interference from another station will be large. To avoid this, you can define the start timer. In this example a start time of 04 means that the first transmission will start at 4 minutes past the hour, and subsequent transmissions will commence at Frame minutes after that in this case, 14, 24, 34 etc minutes past the hour.

WSPR call G0UPL

The WSPR callsign is the first parameter which is encoded into the WSPR message. Your callsign must obey certain restrictions imposed by the WSPR protocol. These restrictions helps ensure that

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the WSPR encoding process can compress callsigns efficiently, along with the Maidenhead Locator square and Power level, into only 50 binary bits of information in total.
The callsign can only be 4 to 6 characters long. The callsign must consist of the following:

One character which can be A-Z or 0-9 or a SPACE 2) One character which can be A-Z or 0-9 3) One character which must be a number 0-9 4) Three characters which can be A-Z or a SPACE
For callsigns such as mine, consisting of 5 characters, I must enter a space character as the first character in order to satisfy these callsign rules. Others with two character prefixes like VK6JY would need a space character at the end “VK6JY “.
If the callsign you enter does not obey the necessary rules, then an error message is displayed on exiting the configuration menu system:
Beacon error: Callsign
In this case, go back to the WSPR Call parameter and try to understand how to correct it in order to make your callsign satisfy the requirements.
Note that if entering the callsign text using the key, you cannot enter a space with the key! So, you will need to enter the initial space character (if required) using the buttons and rotary encoder as discussed in the earlier section on editing TEXT parameters.

WSPR locator IO90
The Locator is the second parameter which is encoded into the WSPR message. It is the 4character Maidenhead square. The text you enter here, must be a valid Maidenhead square, otherwise an error message will be generated on exiting the configuration menu system.
If you have connected a GPS receiver, the GPS receiver will update the Locator, computing it from the latitude and longitude information contained in the serial data string from the GPS receiver module.

WSPR power 37
The third and final parameter encoded into the WSPR message is the transmitter power, defined in dBm. Note that this parameter is manually edited here and is encoded into the WSPR message. It does NOT indicate a measured power which is actually transmitted. This is a common

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misconception. It only indicates what number the operator configured for the WSPR message encoding.
WSPR powers are constrained to certain values 0, 3, 7, 10, 13, 17, 20, 23, 27, 30, 33, 37, 40, 43, 47, 50, 53, 57 and 60dBm. If you specify a value not in this list, then an error message will be generated on exiting the configuration menu system.
In this example, the configured value is 37dBm which corresponds to 5 watts of RF transmitter output.

Set time 10:34
Use this menu item to set the real time clock. When you exit editing the menu, the real time clock is set at this moment. The seconds of the real time clock are set to zero. Therefore when you are setting the clock to use the beacon with standalone WSPR operation (with no GPS connected), you need to wait for the actual time to reach 00 seconds, THEN exit the Set time menu item (press the exit button). This will ensure the time is set accurately.

5.15 Display/controls menu
This menu contains items such as those concerning the elements that are enabled to be displayed on the screen, or the behaviour of buttons; there are also some other miscellaneous items in here which don’t fit elsewhere.

Battery display sub-menu The parameters that control the battery voltage display are contained in this sub-menu.

Enable OFF
This list parameter controls if and how the battery voltage is displayed on the screen at the top right corner. Measurement and display of battery voltage may be useful to those operators who intend to operate the radio from battery power, for example during portable operations. There are three possible values:
OFF No battery voltage is displayed;
Icon A battery voltage icon is displayed, configured according to the following parameters in the following section;
Voltage The top right corner character displays the actual voltage measurement, in a miniature pair of digits; the two bottom rows of the pixels of the

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character have a number of pixels lit which indicate the decimal point of the battery voltage (one pixel = 0.1V). In this example (right) the voltage is 12.2V.

Batt. full 12,000
This is the voltage, specified in millivolts, at which the battery is considered “full”.

Batt. step 1,000
This is the step, specified in millivolts, for each bar of the battery icon. (NOTE: QMX should not be operated at above 12V or below 6V).
In this example, Batt. full is defined as 12V and the step is 1V. The battery icon has 7 possible states, ranging from empty to full and 5 intermediate states in between. The meaning of the displayed icon will be, in this example:
Full: 11.00V to 12V (and indeed, above 12V also) 5 bars: 10.00V to 10.99V 4 bars: 9.00V to 9.99V 3 bars: 8.00V to 8.99V 2 bars: 7.00V to 7.99V 1 bar: 6.00V to 6.99V Empty: Below 6V
Pwr/SWR display submenu
Parameters controlling the display of the Power/SWR meter during key-down are contained in this menu.
The power meter shows in the three meter characters to the right of the mode indicator, with a range from 0 to 6W, each pixel column is equivalent to 0.4W. The SWR meter is shown in the bottom half of the three meter characters, with a range from 1.0 to 4.0. Each column of pixels is equivalent to an SWR increment of 0.2.
In this example (right), power (top half of display characters) is 3.6W and SWR is 1.8. Power and SWR measurements should not be assumed to be high accuracy but are a useful indication.
Pwr/SWR display ON

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When set to ON, an RF Power measurement and SWR measurement is displayed during keydown, as described and illustrated above.

Update interval 100
The update interval in milliseconds, between updates to the Power/SWR meter. For a more rapidly updating and more responsive display of power, lower values such as 25 or 50ms may be preferred.

TX->RX hang time 50
The number of milliseconds that the Power/SWR meter is still displayed, after the transceiver switches back from Transmit to Receive.

S-meter display sub-menu
Parameters controlling the display of the Power/SWR meter during key-down are contained in this menu.
The S-meter, when enabled, is displayed in the top half of the display, in the three characters immediately right of the mode indicator. It is a true dB S-meter, calibrated in S-units. The signal detection occurs AFTER band pass filtering. In other words, as per convention, each pixel is worth 1 S-unit, which is a signal strength increase of 6dB (see https://en.wikipedia.org/wiki/S_meter). The absolute level of S0 will depend on the “gain” setting per band, in the Band Configuration screen. It is independent of volume setting. The default values should be approximately correct but there is some dependence on the band pass filter adjustments etc. The range of the S-meter is therefore S0 (-127dBm) to S9+36dB (-37dBm).
There are two styles of S-meter, as follows.

Simple S-meter
An example showing the simple S-meter style pictured, right. Signal strength is indicated by a thick bar occupying the central 6 rows of pixels of the three meter characters. In this example, the signal strength is S7.
S-meter + AGC action
If the “AGC display” parameter is “ON”, and the “AGC dB per bar” parameter is non-zero, then the S-meter display is split into two sections as shown (right). The top bar indicates the signal strength (the same way as in the simple S-meter case). The lower bar of the meter display indicates the current AGC attenuation applied. Each

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column of pixels is a number of dB of AGC attenuation determined by the “AGC dB per bar” parameter setting. In this example, the “AGC dB per bar” was set to 3, “AGC display” was “ON” and a strong signal was received. The example picture shows a signal strength of S9+30dB (because 14 columns of pixels are shown; which is S9 + 5 x 6dB per column = S9+30dB). The AGC shows 13 columns of pixels which indicates an AGC attenuation of 39dB (13 x 3dB, the AGC dB per bar setting).
S-meter ON
When set to ON, the S-meter measurement is displayed during receive, as described and illustrated above.
Update interval 50
The update interval in milliseconds, between S-meter display updates.
AGC display ON
When ON, and if the “AGC dB per bar” parameter is non-zero, the S-meter display is split into two bars; the lower bar shows the applied AGC attenuation. See above for full description.
AGC dB per bar 1
When non-zero, and AGC display is on, the S-meter display is split into two bars, the lower bar shows the applied AGC attenuation and each column of pixels is the “AGC dB per bar” number of dB.
Main Display/controls menu parameters: The following items are in the main Display/controls menu, not a sub-menu.

QMX operating manual; firmware 1_00_018

Dbl. click 300
This is a NUMBER parameter which controls the decisions on what type of press has been made to a button. By default, it is set to 300 milliseconds (as shown here) but you may alter this if you wish.
It is the number of milliseconds after first pressing the button, at which certain decisions are made:
a) If you have not pressed the button again after this interval, then it means you intended a single press.
b) If you are STILL pressing the button all this time later, 300 milliseconds after the first press, then it means you executed a “single long press”.
c) If you pressed the button again before the 300 milliseconds elapsed, it is a “double click”.
Some operators may find 300 milliseconds is rather too fast to cleanly execute a “double-press”. In this case you wish to try a slower value such as 500ms.

Cursor blink OFF
Two different cursor styles are possible. You can select your favourite, here. The two possible values are an underline cursor (the default), and a blinking cursor (the display alternates between the edited character, and a solid white block).
When set to ON, the cursor style is Blink. When OFF, the cursor style is Underline (default).
Note that this setting only affects the cursor that is shown during menu system editing. In normal operating mode, the underline cursor is always used for tuning rate indication, regardless of the Cursor style setting.

Custom splash NO

You can use this configuration to display your own customized “Splash” screen on powering up the QMX. Ordinarily when you power up the QMX it will show this screen:

QMX

1_00_009

QRP Labs, 2023

It shows the firmware version number (1.00_009 in this example). When you set the “Custom splsh” configuration parameter to YES, the contents of message memories 11 and 12 are

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displayed on the top and bottom rows respectively. You would then not normally use these message memories for sending CW (though the system does not prevent it). If either memory 11 or 12 are blank, the default splash screen contents for the upper or lower row respectively will be shown. Therefore it is possible to customize one or the other or both rows, as you wish.
Clock OFF
When set to ON, a real time clock is displayed in the bottom right part of the screen during operation. The time is NOT maintained when the QMX is powered down. You may set the clock by connecting a GPS such as the QRP Labs QLG2, or in the Set time parameter which is in the Beacon menu or System config menu. Remember that the GPS and the paddle share the same microcontroller inputs (see schematic) and therefore the GPS signals key the transmitter. The QMX automatically detects the presence of GPS serial data and enables “Practice mode” to prevent keying (a G appears on the top line of the display) that due to the high duty cycle, could damage the Power Amplifier transistors if applied for a long duration. The QMX automatically parses the serial data when the GPS is connected (without needing to be in a GPS calibration menu in the Alignment menu, or operating in beacon mode). When the GPS is disconnected, the temporary Practice mode is automatically disabled, restoring normal operation of the transceiver. Therefore you may simply connect a GPS, wait for the real time clock to be updated, and then disconnect the GPS. This is a convenient way to set the time easily, if you have a shack GPS operational.
Delim ,
This parameter configures the delimiter character that appears between the MHz, kHz and Hz parts of frequency or numeric displays on the QMX screen. The default is a comma. Now the operator may select a dot if preferred; for example European convention is the use of a dot as the thousands separator.
Backlight ON
This parameter controls whether the backlight is ON or OFF. This setting is saved in EEPROM and is applied at the next power-up automatically. The display is sunlight readable even with the backlight switched off. Switching off the backlight saves approximately 7mA of current consumption (at 12V supply).

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5.16 Protection menu
SWR protection ENABLED
When SWR protection is enabled, the SWR is measured using the onboard SWR bridge at intervals of 1 millisecond. If the SWR exceeds the configured threshold then the transmitter is disabled by an automatically set protection mode in which the letter `S’ is shown in the character immediately to the right of the frequency display. Transmission is inhibited until this error condition is cleared. The error state is cleared by entering and leaving the configuration menu, or cycling power.
SWR threshold 3
The SWR threshold at which transmission will be inhibited, if SWR protection is enabled.
Tune % 50
During the SWR sweep and SWR measurement tool operation (see later in this manual) the supply voltage to the Power Amplifier can be reduced in order to protect the PA transistors (SWR protection is not enabled while running these tools). Remember that there is a square law relationship between RF power output and PA voltage. The default Tune PA voltage of 50% means that the RF power output will be one quarter (25%) the full power value.
GPS protection ENABLED
When enabled, if a GPS is connected to the paddle port, keying of the transmitter is automatically prevented; this parameter is also available in the Keyer menu, please refer to the Keyer menu description of this parameter above.

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Supply voltage Prevent TX
This parameter controls protection against out-of-range supply voltages. It has three possible values: OFF supply voltage range checks are disabled Warn the battery voltage icon, if displayed, flashes to indicate the supply voltage range violation Prevent TX while the battery voltage is out of range, the transmitter is disabled
Min voltage 7
The minimum supply voltage for the range check enabled by the Supply voltage protection.
Max voltage 13
The maximum supply voltage for the range check enabled by the Supply voltage protection.
5.17 System config
This menu contains several system configuration parameters which don’t seem to belong in any other menu.
Band version 80-20m
Displays the band version of your QMX. You will have selected this at first power-up of your QMX. You can change it in this menu but the Band Configuration and other parameters will not be changed to reflect it; if you have chosen the incorrect band version at power-up and wish to reset the configuration appropriately for the version you built, the best way to do this is using the Factory Reset feature.

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TCXO frequency 25,000,000
Default is 25000000 (25 MHz). This is the oscillation frequency of the QMX TCXO (Temperature Controlled Crystal Oscillator) and is used for calculating Si5351A parameters for setting the desired QMX operating frequency.
The supplied TCXO is a high precision component and will normally be found to be within (a one standard deviation error of) +/- 5 Hz of the specified 25 MHz value. It is not normally particularly necessary from an operating perspective, to have a more precise operating frequency than this. Remember that the error is also scaled to the operating frequency. So a 5 Hz error at 25 MHz will translate to a 2.8 Hz error at 14 MHz.
However the perfectionists among you may wish to calibrate your operating frequency precisely and this menu entry is for you!
To configure the correct TCXO reference frequency, you will need to measure your operating frequency, deduce the error amount, and apply a correction to the TCXO frequency configuration parameter.
As an example, suppose your transceiver is set to a USB “Dial Frequency” of 14.0956 MHz and WSJT-X is set up to transmit WSPR at 1500 Hz audio offset. This should result in a transmission frequency of 14.097100 MHz. But let’s suppose that you measure it accurately, and you find that it is 3 Hz high, at 14.097103 MHz. Now what?
There’s an error of +3 Hz in your operating frequency. To work out the required correction to the TCXO reference frequency configuration, calculate 3 Hz multiplied by a ratio of 25 MHz / 14.0971 MHz, which results in 3 Hz x 1.77 = 5.3 Hz. Therefore you should increase the reference frequency by 5Hz. So edit the TCXO frequency to 25,000,005.
How about if you don’t have an accurate way of measuring your operating frequency? I have developed tools for QRP Labs website to help you to use the WSPRnet reporting network to determine your operating frequency quite accurately. To use these tools, simply use WSJT-X and QMX to operate as a 20m WSPR reporter (receiver) for several minutes, then look at this page:
https://qrp-labs.com/images/wsprnet/rxerror.html
Look for your callsign in the list, which shows the error in your reception reports (operating frequency error). Alternatively, you may operate as a WSPR transmitter using WSJT-X and QMX, and the following page will show your actual transmitting frequency:
https://qrp-labs.com/images/wsprnet/txfreq.html
Both of these QRP Labs pages are updated every two minutes. The analysis loads the last 2 minutes (approximately) of 20m WSPR reports from the WSPRnet website database. It crossreferences all the reports, analyzing the error of receiver stations by cross-referencing against reports of the same transmitters by other stations. In this way calibration errors of all receiving stations in the network are averaged out. The accuracy is generally within 1 or 2 Hz.

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Japanese limits DISABLED
When this setting is enabled, QMX will refuse to go into transmit mode if the specified synthesis frequency is outside the Japanese band limits as specified in the JARL bandplans document https://www.jarl.org/English/6_Band_Plan/JapaneseAmateurBandplans20200421.pdf. This setting is useful for Japanese license regulations compliance.

CAT timeout ENABLED
When this setting is enabled, which it is by default, there is a timeout on Transmit; if the timeout elapses and QMX does not receive a CAT command requesting it to switch back to Receive, then it will automatically switch back to Receive. This feature needs to be disabled if using VOX.

CAT timeout (s) 120
The duration of the CAT command timeout (see above), in seconds.

PTT as Serial 3 NO
Enabling this parameter changes the behaviour of the 3.5mm PTT jack. This jack becomes an additional serial port. This requires a HARDWARE change to remove and bypass the transistors driving the PTT signals. The port is then a 3.3V logic (5V logic tolerant) serial port with configurable baud rate.

IQ Mode DISABLED

When IQ mode is enabled, the raw I and Q channels from the ADC are fed to the USB soundcard directly, without any demodulation. This is suitable for people wishing to experiment with using QMX as an SDR front end, with PC SDR software to demodulate I and Q channels.

IQ Mode is not suitable for use with WSJT-X and other Digi mode programs.

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Sideband USB
This setting determines the demodulation sideband. Normally Upper Sideband (USB) is used for all digital modes, and is the default setting. If you wish to use Lower Sideband (LSB) for some reason, you can change it here. Use the left and right arrow keys to change between LSB and USB.
CW-R OFF
This boolean parameter enables the CW-R mode. Ordinarily CW is received in Upper sideband with a 700Hz offset. There may be some occasions where operation on the other sideband is desired (lower sideband), for example to exclude an interfering nearby station when the CW filter performance is asymmetric. In these cases you can switch on CW-R by setting this menu item to ON, to select Lower sideband reception mode.
Set time 00:26
This menu parameter is used to set the real time clock. For further description please refer to the Beacon menu description, above.

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Advanced config!

Selecting this (by pressing the left button) enters the Advanced configuration sub-menu. Ordinarily you should not need to change anything in this menu, and doing so may damage your QMX! It is highly recommended NOT to change anything in the Anvanced configuration sub-menu unless you really understand the consequences of your actions.

CAUTION! Danger! Proceed anyway?
To underline the un-recommended-ness of entering or changing anything here, when you select the Advanced configuration sub-menu you will receive a warning, and have to press the “Select” button again. The following FOUR settings exist in the “Advanced config!” sub-menu.

DO NOT DISABLE!!

The first item is just an informational message, warning you again, to NOT disable any of the subsequent three options! You see I’m really quite serious about warning you:
DO NOT MEDDLE HERE!
(unless you really understand what you are doing, and accept taking the risk).

Mod. High in RX ENABLED

This parameter controls whether the PA amplitude modulator is set to High during Receive. If set to “ENABLE” the PA voltage is high during Receive. This means the PA voltage is around +12V (assuming +12V supply) during Receive.
The BS170 transistors are all off (zero gate voltage) and therefore there is no current flow through the PA transistors. However the Drain-Source junction of the BS170 MOSFETs have a capacitance which is dependent on applied voltage and it is best to MINIMIZE this capacitance, and therefore the effect of the inactive PA on the receiver, during Receive. Furthermore the BS170 MOSFETs have an intrinsic “body diode” which will, at some level, act to clip the incoming Receive signal; by applying a +12V reverse bias to this body diode, we can ensure that this never happens.

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Leaving this setting at “ENABLE” is recommended to maximize theoretical dynamic range and IP3 performance of your QMX receiver, though the actual improvement has not been determined experimentally by measurement. I am grateful to John Dzbrozek KJ4A for suggestion this feature as a result of his PA simulations and subsequent theoretical analysis. If you select “DISABLE” for this feature it will not damage your QMX but it may not optimize Receiver performance.
Normal 5ms shape ENABLED
When enabled, the normal 5ms (or similar, depending on configuration) Blackmann Harris envelope shaping is applied on CW and Digi mode rise/fall times. When set to “DISABLE” the Blackmann Harris envelope shaping is sped up by a factor of 33.33 times, which has the effect of shortening the rise/fall time to approximately 0.15 milliseconds. This is used for testing the response of the PA envelope shaping and Transmit/Receive switch and corresponding BPF switch stability under fast rise/fall times, which are approximately equivalent to a full amplitude 3.2kHz sinewave component of an SSB waveform and are therefore harsher than the worst case conditions which will be expected during SSB transmissions. This feature is designed for experimental and development purposes. In practical use it should be left at ENABLE.
20/80m BPF TXswap ENABLED
Enabling this feature is part of a protective measure against instability which destroyed BPF the multiplixer on Rev 2 PCBs. It is described in this forum post: https://groups.io/g/QRPLabs/message/113662 and you are recommended to read this if interested. Disabling this feature, particularly on an 80-20m Rev 2 (and above) QMX PCB, is REALLY NOT RECOMMENDED.

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5.18 Hardware tests
The hardware tests menu provides access to several application tools designed to allow you to optimize and test your QMX hardware. Additional hardware test tools are available when you connect a terminal (see subsequent sections).
GPS Viewer
GPS viewer
The GPS viewer tool provides three screens which display information about the GPS data being parsed, if a GPS is plugged into the paddle port. You can scroll between the three available screens using the TUNE knob.
06AUG23 16:28:31 A 3D f13 t21 s36
The first screen is an overall status screen. If no GPS is connected, it will simply state “No data” and the subsequent two screens will contain the headings only, with no values. When a GPS is connected, the screen shows the main data, as follows:
· Date: the UT date; in this example it is 6-August-2023. · A heartbeat appears between the date and time fields, which blinks in time with the
incoming 1pps signal, so allows you to verify its correct operation. · Time: this is UT time in 24-hour format; in this example it is 16:28:31. · Validity flag: A means the GPS has acquired enough satellite data to compute a fix; V
means invalid (as yet, no fix). · 3D: indicates the type of fix, 2D or 3D · Number of satellites in fix (solution). f is for “fix”. Here, 13 satellites are used in the fix
computation. · Number of satellites being tracked. t is for “tracked”. Here, 21 satellites are being tracked. · Average signal strength of tracked satellites. s is for “Signal”. In this example, it is 36 dB.
LT 51 30.08321 LN 0 08.96731
Latitude and longitude.

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Grid IO91FE Alt 23.749
The grid subsquare and altitude.

SWR measurement

A 7,074,00 50%

40m

SWR: 1.04

The SWR measurement tool enables the transmitter at a reduced supply voltage determined by the operating percentage defined in the Tune % parameter of the Protection menu. This percentage is displayed for information on the top right of the screen.
The top left shows the operating frequency for the SWR measurement, which is the center frequency of the band.
The band name is displayed in the bottom left, and SWR measurement in the bottom right. The SWR measurement is updated ten times per second.
Controls:
· Use the right rotary encoder to change the band. · Start the SWR measurement by pressing the left push button (Keyer/RIT/Menu). The SWR
will continue to be displayed until the SWR measurement tool is closed, or the left push button is pressed again, or the rotary encoder is turned to change the band, or a 60 second timeout expires. · Use the right push button to exit the SWR measurement tool.

5.19 Factory Reset
This menu item can be used to cause a factory reset. Factory reset returns you radio to the supplied default factory configuration. Everything is erased and set back to the default parameter values. In order to prevent accidentally triggering this drastic step, the factory reset is implemented as a two-step process.

Factory reset Sure? Click Tune

After pressing the Select button to activate the Factory reset, the screen will ask you if you’re Sure? Press the TUNE knob to confirm.
Factory reset takes a few seconds while the entire EEPROM contents are written.

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5.20 Update firmware
This menu item can be used to reboot QMX in the bootloader mode, activating the QRP Labs Firmware Update procedure (QFU). Again it is implemented as a two-step process.
Update firmware Sure? Click Tune
After pressing the Select button to activate the firmware update, the screen will ask you if you’re Sure? Press the TUNE knob to confirm. QMX will reboot into bootloader mode, and appear on a USB-connected PC as a USB Flash drive. You can then copy in the new firmware file. This procedure is described in more detail in a following section.
5.21 AGC system
The following is a detailed description of the AGC menu and operation of the AGC menu, which is a sub-menu of the Audio menu. The same menu parameters are available in both the terminal interface and the QMX LCD itself.

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Before delving into the audio parameters it’s necessary to explain some basic background on the audio processing in QMX and the AGC concepts applied. Feel free to skip this theoretical section if you just want to get on with it and try some AGC parameter values.
The receiver signal path from the QMX’s antenna port BNC connector to the audio output earphone 3.5mm stereo jack connector is as follows:
1. Signal passes through the SWR bridge hopefully having very little effect on it.
2. The solid state PIN-diode switched Low Pass Filters which are critical for suppression of harmonics on transmit, are also kept in-circuit on receive.
3. The Transmit/Receive switch Q508 acts as a SPST switch, allowing the signal to pass through to the band pass filters.
4. The set of switched band pass filters filter far out-of-band signals.
5. The double-balanced Quadrature Sampling Detector (QSD) includes a phase- splitting transformer R401 and sampling capacitors C416-C419 and is responsible for conversion to baseband.
6. Differential instrumentation amplifier configuration pre-amplifier is made up of high performance, low-noise, low distortion op-amps type LM4562. This amplifies the I and Q channels coming out of the QSD, and prepares them for the differential-input ADC chip. The stage also implements some limited low pass filtering. The gain of this stage is chosen carefully to optimize the ADC chip’s dynamic range window.
7. The PCM1804 24-bit stereo ADC chip IC407 digitizes the I and Q channels at 48 ksps (kilo samples per second). This digital representation of the I and Q baseband signals is transferred to the microcontroller over an I2S interface at a bit-rat of 3.072 Mbps. This Audacity recording screenshot of some zoomed- in audio should illustrate the sampling.

8. The microcontroller accumulates samples into memory and processes them in blocks of 32 samples at a time, for the remaining DSP that implements the SDR. There are therefore 1,500 of these 32-sample blocks processed per second, which is crucial to the understanding of the AGC system.
9. Samples are represented internally in the QMX DSP as floating point numbers. Therefore full resolution and high dynamic range is maintained, unlike some SDR implementation which use 16-bit (or less!) integer representations. QMX has a powerful 32-bit ARM Cortex M4 CPU with floating point unit running at 168MHz so there is plenty of processing power.
10. The I and Q signals are mixed digitally in DSP to the 12kHz Intermediate Frequency.
11. I and Q channels are decimated to 12ksps (a factor of 4).
12. A 90-degree relative phase shift is applied (Hilbert Transform).

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13. The resulting shifted signals are added or subtracted depending on whether Upper or Lower sideband is desired.
14. Audio bandpass filtering is applied (CW filter, 300 Hz bandwidth centered on 700Hz).
15. Apply a gain of 3.46 to compensate for filter amplitude impact
16. Apply the 20dB fixed, plus the gain specified in the Band Configuration screen. Mathematically this is equivalent to a multiplication of each sample by 20 log10 (Band onfigurationGain + 20)
17. Run the Goertzel algorithm (like a single-bucket FFT) to obtain an amplitude number used by the CW decoder.
18. Interpolate back to 48ksps (including implicit anti-alias filter)
19. AGC processing (more on this later!)
20. Subtract 48dB (divide by 256)
21. Add sidetone shaping and any mute/de-mute shaping
22. Deliver the 32-sample procssed block to the 24-bit 48ksps USB sound card interface
23. Apply volume gain control (including both the fixed attenuator that is one of 0, -20, -40, -60, -80, -100dB, and the 0 to 200dB gain selected by the volume control knob.
24. Send the block of 32 output samples to over the serial I2S bus at 3.072 Mbps to the 24-bit stereo DAC chip IC401
25. There is an op-amp audio driver per channel at the output of the CS4334 IC401 DAC chip, having a gain factor of 1.7 (+4.6dB), fed to the 3.5mm stereo output jack for the earphones.

AGC processing is done in chunks of an integral number of these 32-sample blocks. The number of blocks in an AGC processing chunk can be from 1 to 9. In this chunk of samples, the peak amplitude is detected (peak sample value). Negative values are inverted which effectively results in full-wave rectification of the sampled signal.

It is important to understand the chunk time needs to contain enough samples to reliably detect peaks in the frequency of interest. The QMX CW filter is a 300Hz bandwidth filter centered on 700Hz. It therefore passes 550-850 Hz. For the same of round numbers, say we wish to detect peaks on a 500Hz signal. We need 1 millisecond to do that since 1 / 500 = 2 milliseconds but we only need half a cycle due to the full wave rectification. The 32-sample blocks arrive 1,500 times per second so each block arrives every 667 microseconds. Therefore practically speaking, the number of 32-sample blocks to use for the detection period must not be less than 2.

The entire AGC system operates on dB values, using a reference base value equivalent to S0 (Smeter) which means -127 dBm.

LATENCY:

Another important point is that the AGC system implements a delay buffer the length of the number of sample blocks used in the AGC processing chunk. The reason for this is that a peak is detected in the current chunk, and is immediately applied to the same chunk, preventing any strong signals getting through at all. However this does inflict an additional latency on the audio signal path, which may need to be kept in mind. For the minimum practical chunk size of 2, the latency added by the AGC system is 1.3 milliseconds.

QMX operating manual; firmware 1_00_018

This diagram introduces the first features of the AGC system. An AGC threshold is implemented, specified in S-units. Below this AGC threshold, nothing happens. There is a one-to-one correspondence between the input signal level and output signal level. Practically, I think it makes sense to choose a threshold which is above the band noise level.

Secondly there is a slope, which is expressed in dB per dB; how many dB of input signal level change is required to create a 1dB change in output signal level. In this example, the slope is 6. In other words, when the input signal increases from S3 to S9, the output signal will only be S4. For operators desiring a gradual AGC, a low number can be used. For a very aggressive AGC in which after the AGC threshold, all signals are practically equalized, you can choose a high number (the maximum you can enter is 99).

There is an automatically calculated “Gain” parameter, called “S9 sounds like S”. The point of this parameter is that if you switch AGC on/off, if for example you have “S9 sounds like S” set to 9, then an S9 signal will sound the same. Regardless of AGC being ON/OFF, the S9 signal will be at the same audio level in the headphones.

The first stage of the AGC system is a noise filter in which sudden impulses can be suppressed without triggering the full AGC action. Any peaks within a given noise filter duration, activate the AGC (to remove the noise impulse). But they do not start the AGC hang timer. The noise filter timer duration is configurable. The units of this parameter are not milliseconds, they are the number of 32-sample blocks, each block has a duration of 0.667 milliseconds (667 microseconds).

Any genuine large signal lasting beyond the noise filter timer duration, activates the AGC properly. It also starts a hang timer which holds this AGC action peak level for the specified duration. The units of this parameter are not milliseconds, they are the number of 32-sample blocks, each block has a duration of 0.667 milliseconds (667 microseconds).

At the expiry of the hang timer, the AGC attenuation is reduced at the “recovery rate” which is specified in dB per second, until the AGC system is back at full gain (zero attenuation).

One final detail is that the application of a sudden instant attenuation to the audio signal path, such as on the incidence of an impulse noise that exceeds the AGC threshold and activates the AGC, can create a little click in the audio (as for any large instant discontinuity). If you have a noisy

QMX operating manual; firmware 1_00_018

band, and the AGC threshold is near the band noise S-level, it can sound kind of “scratchy”. To eliminate this, the application of the AGC attenuation, both on the attack and decay of the AGC attenuation, is spread over a configurable number of the 48ksps samples. This parameter can be set to zero (if you wish to hear the scratchiness). The maximum value cannot be more than the number of samples in an AGC processing chunk so if the samples parameter is set to 2 blocks, at 32 samples per block, that means the application of AGC can be spread over a maximum of 64 samples. But this maximum is automatically calculated and applied by the code.
The action of the AGC can be displayed on the S-meter, if the “AGC display” parameter is “ON”, which is useful for keeping an eye on how the AGC system is operating.

AGC settings menu parameters

AGC: ON/OFF parameter which enables the entire AGC system. The AGC system is only operational in CW mode.

Threshold S: The AGC threshold parameter, expressed in S-points. Below this level, no AGC action is applied; the level of the output signal rises proportional to the input signal.

Slope dB per dB: The number of dB change in the input signal that creates a 1dB change in the output signal (or equivalently, in S-points). If you want a gentle AGC action, so that stronger signals still sound louder than weak ones, choose a relatively low value. If you want an aggressive AGC action, that makes all signals louder than the AGC Threshold sound the same, choose a large value.

Noise filter: The duration of the noise filter, that deletes impulse noise from the signal path without starting the hang timer or rest of the AGC system. The parameter is expressed in units of the 32-sample block time, which is 667us, multiplied by the “Sample blocks” parameter. So for example if “Sample blocks” is 3, that means 96 samples are used for the peak detection, which takes 2ms; then if the Noise filter is set to 10, the noise filter timer duration is 10 x 2ms = 20ms.

Hang time: If a peak is detected longer than the noise filter timer, then this AGC peak is applied (as a negative gain a.k.a. attenuation to reduce the input signal), and the hang timer is started. During the hang period, the peak attenuation is held constant; if a new higher peak is detected, this becomes the new peak value and the hang timer restarts. At the expiry of the hang timer, the attenuation starts to reduce, bringing the AGC system back up to unity gain.

Smooth samples: This parameter, if non zero, means every change in the AGC attenuation level is divided into this number and is applied to each of the 48ksps samples incrementally. So for example, if a 10dB noise spike is detected, and the “Smooth samples” parameter is 50, then the 10dB change in AGC attenuation will be applied over the course of 50 samples, 0.2dB at a time until the full 10dB attenuation is reached. When sudden changes are instantly applied, it creates a little click in the audio which can sound scratchy if there are many sudden changes.

Recovery dB/s: The recovery rate of the AGC gain, after the expiry of the hang timer. So for example, if Recovery dB/s is 10, and the AGC peak was 20dB above the AGC threshold, resulting in 20dB of attenuation to compensate for the strong signal, then at the end of the hang time, the attenuation recovers at a rate of 10dB per second, so that it takes 2 seconds for the AGC to return to zero gain.

Sample blocks: The number of 32-sample blocks to use for the peak detection logic. Numbers less than 2 should not be used. If 2 blocks are used, the duration of the peak detection is 1.5 milliseconds, which equates to an audio frequency of 666.7 Hz; however since the peak detection performs full-wave rectification, we get TWO peaks per cycle, so effectively we can detect a 333

QMX operating manual; firmware 1_00_018

Hz signal. Which is plenty low enough, considering the 550-850 Hz CW bandpass filter. It is recommended to set Sample blocks to 2. More than 2, causes some audible artifacts on Transmit/Receive changeover in full break-in CW.
S9 sounds like S: Separate to all the above discussion of AGC attenuation, this parameter allows the application of a fixed gain. It anchors the audio level so that when the AGC is switched OFF/ON, the volume at that input level is fixed. Therefore if a parameter value of 9 is chosen, an S9 signal will sound the same, whether or not the AGC is ON or OFF.
AGC display: The action of the AGC can be displayed under the S-meter, if the S-meter is enabled, and this parameter is “ON”.
In that case the S-meter is displayed on the top half of the three characters to the right of the mode indicator symbol; the AGC attenuation level is displayed on the bottom half. The number of pixel columns is the number of dB of AGC attenuation divided by the “AGC db per bar” parameter.
AGC dB per bar: As discussed above: if the “AGC display” is “ON”, and if this parameter is nonzero, then the AGC attenuation is shown on the bottom half of the S-meter display. In this example, if “AGC dB per bar” is 3, then the AGC attenuation is 39dB since 13 columns of pixels are shown. This feature is useful for keeping an eye on the AGC action.

QMX operating manual; firmware 1_00_018

6. Operating QMX on digital modes
Operation of the QMX transceiver on digital modes is really simple. A USB-C cable is required between the PC and the QMX. Naturally you need a power supply and the antenna connection too.
QMX must be set to Digital mode, to be able to use the PC and QMX combination for digital modes! Press the VOL knob to change the mode on QMX.

Drivers
The QMX audio device (USB soundcard) is standard on all PC types (Linux, Windows, Mac) and no additional drivers are required.
For the Virtual COM serial port, no additional drivers are required for operation with most Linux distributions, Apple Mac or MS Windows 10 or Windows 11.
For older versions of MS Windows, it may be necessary to install a driver for the serial port because this driver is not on your computer already by default. This driver is available from the ST Semiconductor website at https://www.st.com/en/development-tools/stsw-stm32102.html and is applicable to 98SE, 2000, XP, Vista®, 7, and 8.x Operating Systems. There is a description for installation on Windows 7/8 on the QRP Labs QLG2 page http ://qrp-labs.com/qlg2 so if in doubt, please check this.

Linux special note
On Linux systems, a particular problem can occur. When the QMX Virtual COM (Serial) connection is detected, the PC thinks that a modem has been connected and starts trying to send it Hayes AT-commands dating back to 1981, implemented on Hayes’ 300-baud modem. Yes! 40 years ago…
The Operating System attempting to send AT commands to your QMX will certainly mess everything up. Not least because when QMX receives a carriage return character, it will enter Terminal Applications mode; this will send all sorts of characters back to the PC (as QMX thinks it is now talking to a terminal emulator) and it will disable CAT command processing, so your PC digi modes software will not be able to talk to QMX. Disaster.
To fix this you need to issue the following commands to disable ModemManager:
sudo systemctl stop ModemManager sudo systemctl disable ModemManager sudo systemctl mask ModemManager
This will permanently stop ModemManager. If for some reason, you actually DO need ModemManager operational, for some other reason… well there IS a way to stop it just for QMX… but Google will be your elmer on this!

Additional information from Greg Majewski:
There is another Linux service, BRITTY, that does the same. BRITTY is a Braille service for access by sight impaired people. I have encountered the problem with the G90 and Ubuntu on a

QMX operating manual; firmware 1_00_018

laptop (Ubuntu full version), Raspberry Pi 3 with Raspberry OS and the Orange PI 800. Here are commands that remove BRITTY:
sudo systemctl stop brltty-udev.service
sudo systemctl mask brltty-udev.service
note output: Created symlink /etc/systemd/system/brltty-udev.service
/dev/null.
sudo systemctl stop brltty.service
sudo systemctl disable brltty.service
These commands are similar as used for Modem Manager service.
WSJT-X configuration
Next it is necessary to set up WSJT-X to communicate with QMX. We will use WSJT-X as the example, because it will be what most people are using. But other software will be identical (for example JS8Call) or similar. There are two parts to the set-up firstly to choose the right USB Sound card, and secondly to set up the CAT communication so that WSJT-X can control the QMX via the serial comm port.
Open the WSJT-X settings window (from the File menu) and select the Audio tab. Select “QRP Labs QMX Transceiver” as the input and output sound card. The below screenshot shows how it looks on my system, which is Linux (Xubuntu 18.04). It will look different on Windows, Mac and perhaps other Linux distros but the basic idea will be the same… you should see something in the drop-down which says something about QMX, and that’s the sound card to select.

QMX operating manual; firmware 1_00_018

Next click the “Radio” tab in the settings window, which sets up the CAT control communication.
The following four settings need to be changed, and are illustrated in the diagram below:
· Rig will be set to None by default, click the drop down and choose “Kenwood TS-440” which should work well with QMX. On some other software, if you find that TS-440 is not present in the list or does not work properly, you could try “Kenwood TS-480”. More details about CAT and debugging any CAT problems are in another section of this manual, where the CAT test terminal screen is described.
· The Serial Port drop-down must be set to the correct port where QMX is connected.
On my Linux system it is either “/dev/ttyACM0 or /dev/ttyACM1. On Linux you can also access a serial port via its unique device name, which will be: “/dev/serial/by-id/usbQRP_Labs_QMX_Transceiver-if00”. This doesn’t change depending on which other devices are connected.
On Windows systems it will be a COM port numbered COM1, COM2 etc. Unfortunately unlike the USB Sound, the serial port name doesn’t contain the text “QMX”. If you are unsure which port to choose for QMX, the easy way to find this is as follows. Unplug QMX. Restart WSJT-X. Look in Settings -> Radio and make a note of the list of serial devices. None of these are QMX (because you unplugged it). Now close WSJT-X, plug in QMX, start WSJT-X and again look in Settings -> Radio, and now you should see a newcomer in the list of available ports. The newcomer is QMX!
· Note that none of the Serial Port Parameters need to be changed, leave them all at their defaults. Even the baud rate 9600 is unimportant because it is irrelevant to the USB Virtual COM Port which is a virtual port over USB, not a real physical serial port.
· Change the Poll Interval to 10 seconds, the default will be rather chatty with QMX which probably is not a problem, but anyway I feel more comfortable with the less frequent polling. QMX has no capability to alter its operating frequency for example by itself, it can only do so at the command of WSJT-X over CAT; therefore the polling is actually redundant anyway.
· Change PTT Method from the default “VOX” to “CAT”. VOX means “voice operated exchange” or “voice activated transmission”; the radio will automatically switch to transmit, when incoming audio is detected. With PTT Method set to CAT, when WSJT-X wishes to start a transmission, it will send an actual CAT command to QMX informing it to start the transmission, before sending the audio. This CAT command causes QMX to switch from Receive mode to Transmit mode (and back again afterwards). “CAT” is preferable to “VOX” because if system sounds are accidentally routed to your “QMX” sound card as output, then with VOX that will enable the QMX transmitter and try to transmit the sound.
· Now click the “Test CAT” button and after a few seconds, it should turn Green to indicate successful communication with QMX.

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NOTE 1: If you are using other software than WSJT-X or JS8Call, then QMX CAT commands should still work with this software. If you encounter difficulties then it is possible that your software is trying to communicate with QMX using CAT commands that are not supported by QMX. In the section of this manual on the CAT Test utility (in the QMX Terminal applications), you will find a listing of the CAT commands supported by QMX. Another useful utility is the log file, which will let you record all CAT commands received and investigate any issues. If CAT commands are missing for your application, QRP Labs can add support for them easily.
NOTE 2: As mentioned above, CAT control of transmit/receive switching is recommended. If you INSIST on using VOX, QMX can support that. For example, you may be using a software application which does not support CAT control of transmit/receive switching and can only use VOX. In that case you should change the QMX transmit/receive switching mode from CAT to VOX in the QMX terminal Configuration utility or in the menu on the QMX itself, which is described elsewhere in this manual.

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NOTE 3: The Data Bits, Stop Bits, Handshake should not need to be changed; however several users have reported that changing them to the settings shown in the orange box has resolved some issues with CAT reliability on Windows Operating Systems.
WSJT-X “Pwr” Slider
The only other point to note is that WSJT-X should be operated with the power slider at the maximum setting. This point is discussed further in the QMX design section which explains that best accuracy in determining the audio tone frequency being sent by the PC, is when the Pwr is at the maximum setting. There is no point to using any setting other than maximum, because QMX only ever transmits at full power (5W), there is no way for it to transmit at a lower power output under command of WSJT-X. If you wanted a lower power output, you would need to use a lower supply voltage. Furthermore, QMX cannot be “over-driven” by too high volume, in the way that a SSB transceiver could.
Therefore the “Maximum” setting for the Pwr slider is highly recommended, it is the optimum setting for QMX operation.

QMX operating manual; firmware 1_00_018

Transmit status indication during QMX digital transmissions The QRP Labs QDX transceiver front panel contains a 3mm red Status LED, which can inform the operator the status during digital transmissions and firmware update. QMX has no such LED. However, QMX has an indicator on the top left character of the LCD, under the `A’ symbol of VFO A. Note that the transceiver must be put into DIGI mode before attempting digital transmissions from WSJT-X otherwise they’re just ignored.
1. TX status is a single dot:
This means that QMX has been put into transmit mode via an appropriate CAT command from WSJT-X, however it is not receiving any audio, so there is no RF output. The usual reason for this is that QMX has not been selected correctly as the output device in the WSJT-X audio settings screen. Refer to the section above on the audio configuration. The single dot could also mean that there is no audio because somewhere in your PC sound settings you have MUTE enabled.
2. TX status is two dots:

This means that QMX has been put into transmit mode via an appropriate CAT command, and that it is receiving audio from the PC; however the audio level is too low, so there is no RF.
Remember that there is a “Rise Threshold” setting in the QMX Configuration terminal application, which defaults to 80% of maximum value. If the amplitude of the audio sinewave coming from the PC is less than 80%, key-down will never be triggered.
It is therefore highly recommended to set the audio output level of the PC to 100%. Unfortunately this simple recommendation can be the cause of great c

QRP Labs QMX 5W Digi Transceiver Instruction Manual

QMX 5W Digi Transceiver

Product Specifications

Product Usage Instructions

1. Overview of Features

2. Connectors

3. Display Elements

4. Operator Controls

5. Firmware Update Procedure

6. Terminal Applications

Frequently Asked Questions (FAQ)

Q: Can I use the QMX for PSK31 and phase shift modes?

Q: How many VFOs does the QMX have?

References

Read User Manual Online (PDF format)

Download This Manual (PDF format)

QRP Labs User Manuals

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