ITAM UHF-VHF Stehwellen And leistungsmessung Power Measurement Instructions

: July 23, 2024
: ITAM

Table of Contents

elements
OPERATION MANUAL
Specifications
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ITAM UHF-VHF Stehwellen And leistungsmessung Power Measurement Instructions

elements

TXsocket
ANT socket
CAL adjustment
REF-FWD / 10W-100W switch
scale
SWR-PWR -switch

OPERATION MANUAL

Introduction
The SWR-PRO CB is designed to measure the transmission power and the standing- wave-ratio of radios that operate in the frequency range of 120- 500 MHz. The SWR-PRO-UHFNHF is a compact dual-function test meter to indicate the condition of any CB antenna system and transmitter with an impedance of 50 Ohm.
SWR Function
Testing for the· SWR or standing wave ratio, provides the operator of the transceiver a good indication of the condition of his antenna and antenna lead cable. In order to get the maximum power radiated from the antenna, the coax- cable and the antenna should be matched to the transmitter. A perfect match is never achieved. The amount of mismatch can be measured
by measuring the amount of standing waves that exist in the coax of the antenna feed line. Measuring of the standing waves can be accomplished by sampling the forward FWD power and the reflected REF power and comparing them and then expressing this difference as a ratio of reflected to forwarded power. In the table 1 are some examples of amount power loss for a standing wave ratio.
SWR Measurement
Do not turn on the transmitter, while the antenna and test meter are disconnected.
To use this SWR meter, it must be connected to the antenna feet line with a short coaxial cable, not longer than two feet. With the transmitter off, disconnect the antenna coax cable from the transmitter and connect the coax cable to the jack of the SWR meter marked with ANT (2). Connect the short coax cable between the transmitter and the TX-jack (1) of the SWR meter.
If a long antenna coax cable is used and the antenna should be matched, the measurement is more exact if the short coax cable connected between the antenna and the ANT jack at the SWR meter. With this setup the antenna coax cable does not influence the measurement.

Place the sliding switch (4) [FWD/REF] to FWD.
While pressing the radio’s PTT, turn the calibration knob [CAL] (3) until the needle reaches the infinity symbol oo at the end of the scale.
Now, place the switch (4) [FWD/REF] to position [REF]. While still holding the radio’s PTT, the standing-wave-ratio can be read at the lower part of the scale (6).

If the SWR is above 2: 1 the antenna may need tuning or there may be a problem in the antenna system (connectors).

Several antennas provide a means for tuning by either a slide adjustment or a control at the base. For sliding antennas, sliding ¼” each time and repeating the SWR measurement steps after each adjustment. First, move the antenna inwards and observe for an improvement in the SWR, than outwards if no improvement is noticed. Select a center channel at the transmitter for the measurements.

4. Power Meter Function
The power meter function determines the relative power being generated in the transmitter.
The tx power shall not exceed 150 Watts!
This meter will measure up to 10 or 100 Watt RF power (max. 150 W), dependent of the position of the sliding switch (4) [1 0W/1 00W].

5. Power Measurement
Do not turn on the transmitter, while the antenna and test meter are disconnected.

Connect the meter with the transmitter and the antenna in the same way as for the SWR measurement.
For measuring of standard VHF-/UHF commercial transmitter with a max.
RF power of 6 Watts, place the sliding switch (4) [10W/100W] to the 10 W position. Amateur transceivers often operate in a range of up to 100 W.
Turn the transmitter on and read the power from the upper scale (W) (6).

Unusual, high measured power, above the rated power of the transmitter could indicate a faulty antenna system. Check all connectors for unsatisfactory connection.