RigPix SBS-30 CB Free Band Owner’s Manual

RigPix SBS-30 CB Free BandCUSTOMER SERVICE

The SBE Technical Services Department functions as a source of information on the application, installation and use of SBE products. In addition, the Technical Services Department provides technical consultation on service problems and the availability of local and factory repair facilities. In any communications to the Technical Services Department, please include a complete description of your problems or needs, including model and serial numbers of the unit or units in question, accessories being used, any modifications or attachments in use, or any non-standard installation details. For assistance on any of the above matters, please contact SBE, Incorporated, Technical Services Department, 220 Airport Boulevard, Watsonville, California 95076. Phone: 408/722-4177.

PARTS ORDERS

SBE original replacement parts are available from the Factory Parts Department at 1045 Main Street, Watsonville, California 95076. When ordering parts, please supply the following information:

• The model number of the unit.
• A serial number of the unit.
• Part number.
• Description of the part.

FACTORY RETURNS

Repair services are available locally through SBE Certified Service Stations across the country. A list of these Service Stations is available upon request from the Technical Services Department. Do not return any merchandise to the Factory without authorization from the Factory.

SPECIFICATIONS

GENERAL

• Compliance; F.C.C. Type Accepted (Part 95, Class D)
• Channels;23
• Frequency Range ;(26.965-27.255) MHz
• Frequency Control; Crystals, Synthesized Frequency Tolerance +0.003%
• Operating Temperature Range 30°C to +50° C
• Humidity 95%
• Input Voltage 120 VAC or (11.7 – 15.9) VDC positive or negative ground
• Microphone; Dynamic
• Size 2″ (53mm) Height: Width: 64″ (160mm) Depth: 7-7/8″ (200mm)
• Weight 3 bs., 1.36 Kg.
• Power Consumption 40 watts, Full Modulation
• Fuse 2A fast blow (Type 3AG or A.G.C.)

RECEIVER

• Sensitivity 0.7uV for 10db S+N/NN
• Selectivity 6db @ :6 kHz, 50db @ : 10 kHz
• IF Frequency 10 MHz, 455 kHz
• AGC Response Less than 10db for 10-100,000 V
• Squelch Threshold Less than 14aV
• Audio Power Output 2 watts
• External Speaker (Not Supplied) 4 or 82. Disables internal speaker when connected.
• Squelch Range 2004V (Minimum)

TRANSMITTER

• Power Output 4 watts
• Modulation 95-100%
• Modulator Response 300-2500 Hz
• Output Impedance 502, unbalanced
• Emission 6A3

INSTALLATION

GENERAL

The first step in the installation of the SBE-30CB is to select a site that is convenient and permits ac- accessibility to a good antenna location. The selection of an antenna system and its mounting location are the most critical factors in determining performance A vertical ground plane antenna will provide the most uniform horizontal coverage. This type of antenna is best suited for communications with a mobile unit. For point-to-point operation where both stations are fixed, a directional beam antenna will usually increase communication range since this type of antenna concentrates energy in one direction. Beam antennas also allow the receiver to “listen'” in only one direction thus reducing interfering signals. F.C.C. regulations limit antenna height of directionals to 20 feet above ground or any formation and omnidirectional and supporting structure to 60 feet above the ground.

ANTENNA TUNING

The final step in the installation is to trim the antenna for minimum S.W.R. The recommended method of antenna tuning is to use an in-line wattmeter or S.w.R. bridge to adjust the antenna for minimum reflected power on channel 11. A properly tuned antenna system will present a suitable load to the transceiver and will insure that maximum power is transferred from the radio to the antenna. If the antenna system in use presents a poor load, as indicated by a high S.W.R. reading. transmitter range will be sub-stantially reduced and damage to the transmitter’s final amplifier may occur. Poor S.W.R. can usually be corrected by altering the antenna’s electrical length in accordance with the manufacturer’s instruction. Extremely high S.W. R. readings may be indicative of a defective transmission line, antenna, or connections. To determine whether the antenna should be lengthened or shortened, test the S.W.R. on channels 1 and 23. If the S.w.R. is the highest on channel 23, the antenna is too long and if highest on channel 1, the antenna is too short. When the antenna system has been tuned correctly, channel 11 should have the lowest S.W.R. and channels 1 and 23 will be slightly higher.

ACCESSORIES

EMERGENCY DC POWER

If it is anticipated that the unit may be used in the event of a power failure, a 12-volt storage battery may be connected to the terminal strip on the rear panel. Connect the negative and positive battery terminals to the corresponding points on the terminal strip using #14 or larger wire. In the event of AC power failure, the unit will automatically draw primary power from the battery source. When AC power is restored, the unit will automatically return to normal AC operation. It is not necessary to disconnect the emergency DC power source when the AC line is being used. It is recommended that a means to keep the storage battery fully charged be provided.
PUBLIC ADDRESS
An external 8n 4 watt speaker may be connected to the PA jack located on the rear panel of the unit when it is to be used as a public address system. The speaker should be directed away from the micro-phone tO prevent acoustical feedback.
EXTERNAL SPEAKER
The external speaker jack on the rear panel is used for remote receiver monitoring. The external speaker maybe 4 or 82 impedance and should be rated at 3 watts power dissipation. When the external speaker is plugged in, the internal speaker is disconnected. Suitable units are the model SBE-1SP Non- amplified speaker or SBE-1SP/AMP Amplified speaker.
ALTERNATE MICROPHONE INSTALLATION
A desk microphone may be installed with the unit. For best results, a low impedance dynamic type microphone or a transistorized preamplified microphone is recommended. The SBE 100X Preamplified Base Station Microphone or the SBE 200X Non-amplified Base Station Microphone may be ordered and are ready to plug into the unit. If another microphone is selected refer to the schematic diagram for the proper wiring connections to the microphone jack.

FINAL CHECKOUT

Make an operational checkout of the transceiver to insure operation of it and all the accessories installed. Contact other stations and inquire about their location and their reception of your signal. If an Omni directional antenna is used, the distance to other stations contacted should be about the same in all directions. A directional antenna should reach more distant stations in the direction in which it is beamed. Also, inquire whether the stations contacted are omnidirectional or directional and if directional which way they are beamed.

CIRCUIT DESCRIPTION

INTRODUCTION
The SBE30CB is an AM transceiver with a dual-conversion receiver using intermediate frequencies of 10 MHz and 455 kHz. Refer to the block and schematic diagrams while following the circuit description. TRANSMIT MODE is initiated by pressing the push-to-talk switch which energizes relay RL-1 which:
DISABLES

• 1st RX O 2nd RX MIXER (Q6),
• St T AMP (07),
• ec ATORto a1).
• 1st RX AUDIO (Q9),
• EARLIER SP-1,
• ENABLES TY MVE OR (O3), RX PROTECTION DIODE (D1). When the push- to- talk switch is released, the transceiver is in RECEIVE MODE, and the above states

RECEIVER
In receive mode, an R SIgnal is ted from the antenna to the R AMP 4he amplified signal is then fed to 05- the 1st mixerwhere it is mixed with an injection signal trom the MASTERS CILLATOR 02 about 10 MHz below the receive channel frequency. The resultant 10 MHz 1st i 1sS the RX OSCILLATOR 01 455 kHz below the 10 MHz 1st 1F. The ceramic filter FL-1 selects the 455 kHz signal and feeds it to the 1st AMP Q which then reeds it to the 2nd amp 8. the output of 08 is fed through c24 to the AGC detection diodes b and D4, through c86 to the s METER ino through the AUTOMATIC NOISE LIMITER. the detected audio signal is applied across potential meter VR1 – the volume control. The audio signal developed on the VR1 wiper is then fed to audio amplifier stage Q10 which then feeds Q11. The output of di1 drives 12 which is transformed coupled to push- pull speaker driver amplifier Q13 and Q14.
AUTOMATIC GAIN CONTROL CIRCUIT
The AGC (Automatic Gain Control) on the SBE-30CB reduces the gain of the receiver in response to an R2. R19 function and filtered by C25, With a weak receiver input signal – less than 1 V- diodes D3 and D4 are forward biased by current through R2, R27, R28 and R19. About 1.5 volts of AGC appear at the C25, R19 junction. As the input signal increases, the signal at the top of C24 increases. When the signal at the top of C24 swings negative, current flows through D3 on to C24. As the signal swings posi- tive, c24 discharges through D4. The increase in current through R2, R27, and R28 decreases the AGC voltage. The AGC voltage is then fed through R1 and the secondary of T1 to the base of Q4, through R5 and the secondary of T2 to the base of Q5, through R19 and L2 to the base of Q6, and through R12 to the base of Q7.
THE AUDIo DETECTOR
The AUDI0 DETECTOR on the SBE-30CB demodulates the received signal. The output of the 2nd IF AMP is fed from the top of the primary T5 through C22 to the detector diodes D5 and D6. When the signal at the top of T5 swings negative, D5 conducts current on to C22. As the signal swings pos tive, C22 discharges through D6 and charges C26. The voltage on C26 thus tends to follow the peak- to-peak voltage of the received signal and is thus the demodulated audio signal which is then fed through the AUTOMATIC NOISE LIMITING circuit, through C28 to the top of VR1 – the volume control, and from the wiper of VR1 through C39 to Q10- the first stage of audio.
AUTOMATIC NOISE LIMITER CIRCUIT
The ANL circuit prevents impulse noise, such as ignition noise, from being amplified. The audio output voltage from the detector diodes D5 and D6 is reduced by about 1/3 by voltage divider R20 and R21 and then fed to the cathode of D7 the ANL diode. The audio output from the detector diodes is also fed through R22 to C27 where it is filtered and then fed through R23 to the anode of D7. Since the audio signal is positive, the signal at the anode of D7 is normally more positive than the cathode and the diode is forward biased providing a low impedance path for the audio to the first audio stage a10. When a noise pulse appears in the output of the detector, the time constant of R22 and C27 prevents the anode of D7 from responding as fast as the cathode. The cathode of D7 is thus driven more positively than the anode causing D7 to become backed biased. D7 then becomes a high impedance that blocks the noise. such CIRCUIT The squelch circuit shuts the audio off when the received signal is less than the threshold level as determined by the SQUELCH CONTROL. If 09 the SQUELCH AMP- is off, R29, R30, and R31 form a voltage divider network that provides the proper forward bias to the base of Q10 the first audio stage – permitting it to amplify the audio signal fed from the detector. Raising the wiper on VR2 the sQUELCH CONTROL tends to forward bias the base of 09 which turns Q9 on. When Q9 is on, the forward bias is removed from the base of Q10 thus preventing the amplification of the audio signal. As the received signal becomes stronger, however, the AGC voltage lowers the bias on Q9 which then permits Q10 to amplify audio. Thus raising the wiper on VR2 increases the threshold level a signal must overcome to “break squelch” turn 09 off and permit Q10 to amplify audio.
S METER CIRCUIT
In receive mode, meter M1 functions as an S-METER, and indicates the relative strength of the received signal. When the signal swings positive at the top of the T5 secondary, current flows through D16 onto c85. As the signal swings negative, C85 discharges through D15 and charges C84. The voltage on C84 thus tends to follow the received signal strength. C84 discharges through VR5 the S METER ADJ to meter M1.

TRANSMITTER

In transmit mode, the output of the MASTER OSCILLATOR 02 and the TX OSCILLATOR 03 are mixed in the TX MXER D12. The output of D12 is then fed through BAND PASS FILTER L4, and T8 (26.965 27.255 MHz) to the TX BUFFER Q15. The output of the BUFFER feeds the TX AMP 016 which in turn feeds the TX DRIVER a17. The TX DRIVER then feeds the TX FINAL 018. The output of the TX FINAL is then fed through a low pass filter, L8, C78, L10, c80, L11 and C81, and a second harmonic trap CV1 and L12, to the antenna. Modulation is accomplished by driving the collector of the TX DRIVER and TX FINAL by modulated B+ derived from the lower secondary of T7- the AUDI0 OUTPUT transformer.
FREQUENCY MIXING scheme
Channel Selector switch $2 selects one of six crystals (X5 – X10) to set the MASTER OSCILLATOR a2 frequency about 10MHz below the selected channel frequency. (See Table 5.3.) The output of 02 is fed to the 1st MIXER Q5 to produce the 1st IF. $2 also selects one of four crystals (X1 X4) for the RX OSCILLATOR Q1. The output of Q1 is fed to the 2nd MIXER O6 to produce the 455 KHz 2nd IF. One of four crystals (X11 X14) is also selected by $2 for the TX OSCILLATOR 03. The outputs of the TX and MASTER OSCILLATORS are mixed in TX MIXER diode D12. The sum of the frequencies from these oscillators is selected to produce the transmitter frequency.
oVERMODULATION LIMITER
The OML regulates the gain of the audio amplifier so as to accommodate a wide range of voice levels without overrode lat ing the carrier. The audio signal is fed from the secondary of the audio output TRANSFORMER T2 to D18 where it is rectified; it is then filtered by C116, R40, and C43, and fed to the emitter of Q11 the MIC AMP through the OML adjustment VR4. As the sound level in the MIC increases, the voltage at the emitter of Q11 will rise and thus lower the amplification of the sound input.
OSCILLATORS
Crystal oscillators Q1, 02, and Q3 are common collector, Colpitts circuits. Outputs are taken from the emitters. The collectors of Q1, 02, and a3 are at AC ground.
RF OUTPUT METER
In transmit mode, meter M1 functions as a transmitter power output indicator. A small sample of the transmitter’s RF output signal is fed by C82 to network R64, D14, and C11 where it is rectified and filtered and then fed through VR6 the RFO ADJ to meter M1.

FIG. 4-1 SBE-30CB TRANSCEIVER BLOCK DIAGRAM

SERVICING

INTRODUCTION

Read this section carefully before attempting any repair of the SBE-30CB. Refer to the circuit description, block and schematic diagrams. The transistor case diagrams are shown on the schematic diagram. Refer to these diagrams before checking transistors. Component layout and location prints are provided to aid troubleshooting and alignment. Use only recommended replacement parts. Refer to the parts list in the back of this book. Never replace blown fuses with higher rated ones or fast acting with slow blow. To check operation of the unit, refer to Table 5-1, PERFORMANCE VERIFICATION PROCEDURE. Figures 5-4, -5 , TRANSMITTER TEST CONNECTION and RECEIVER TEST CONNECTION
respectively, show the proper manner to connect the unit to test instruments for performance verification or alignment. Table 5-2 lists RECOMMENDED TEST INSTRUMENTS. Tables 5-10, -6 show the proper TRANSMITTER ALIGNMENT PROCEDURE and RECEIVER ALIGNMENT PROCEDURE respectively. Figure 5-8, ALIGNMENT LAYOUT is placed next to the alignment procedures to show alignment adjustments at a glance.

TEST SIGNALS

OSCILLOSCOPE WAVEFORMS are shown which were taken from various points in the SBE-30CB during normal operation into a dummy load. CHECK POINT numbers next to the waveform pictures correspond to numbers in boxes on both the schematic diagram and component layout drawing. Figure 5-11 shows RF amplification through a properly aligned transmitter. Figure 5-12 shows 50%, 100% and overmodu lation respectively. Notice that the waveform at the ANO DE of D 12 – the TX MIXER – contains several frequency components. A lso notice that the waveform at the collector of 018 – the TX FINAL – is unsymmetrical (Figure 5-11e). This is proper since the TX FINAL operates class C for greater efficiency. Figure 5-11f shows how the output should look at the dummy load. VOLTAGE MEASUREMENTS are shown on the schematic diagram for normal operation. All voltages were measured with an AC VTVM having 10Mn input impedance. Voltage measurements on high impedance RF points should be taken through a choke. While any choke about 100μH is suitable, SBE part number 8000-00011-0018 (150μH) may be ordered from the factory. Mini-test clips are very useful for making voltage measurements in hard-to-reach places.
RECEIVER INJECTION VOLTAGES are given in Table 5-9 together with CHECK POINT numbers which correspond to numbers in boxes on both the schematic diagram and component layout drawing. This table specifies the voltage level, carrier frequency and particular points in the receiver string at which a 30% – 1 KHz modulated signal injected through a .01 MFD capacitor should produce 2 VAC of audio across the speaker or an load plugged into the speaker jack, EXT SP. While the value of this capacitor is not critical, capacitive coupling of the signal generator to the circuit is necessary to prevent grounding out the transistor biases. Before setting up to measure RECEIVER INJECTION VOLTAGES, small hand-held “all-purpose signal generators” can be used to provide a quick check of the receiver string. Basically, these devices generate pulses rich in harmonics from AF to RF to test whether a stage is working. AGC VOLTAGES versus RF INPUT LEVEL are shown in Tablet5-7. This table should be consulted before any adjustments are made on the squelch circuit since squelch is a function of AGC.
TROUBLESHOOTING
Troubleshooting the SBE-30CB transceiver is not essentially different than troubleshooting any other electronic device. Be a detective; suspi:?ct everything and everyone. Carefully inspect the unit for evidence of overheated components, cold solder joints, or tampering. Understand thoroughly the circuit description and block diagram. Try to start big and isolate the problem. Devise tests that will divide the transceiver in two and isolate the trouble to a particular half. Continue to divide into two parts until the trouble is located. For example, it is determined that a problem exists in a particular transceiver.
The unit is divided into:
TRANSMITTER – RECEIVER.
Suppose that the receiver functions properly but there is no carrier when the transmitter is keyed. Since the receiver audio works, it can be assumed that all of the audio amplifiers is good except the MIC AMP 010 – the condition of which is yet unknown. The MASTER OSCILLATOR can be assumed working since it is used by both the transmitter and receiver. After checking the TX/RX relay
RL-1 and transmitter B+, the transmitter is then divided into:
BEFORE TX AMP – TX AMP and AFTER.
Figure 5-11, TRANSMIT ALIGNMENT WAVEFORMS, shows typical waveforms taken at various points in an SBE-30CB transmitter during normal operation. Place an oscilloscope probe on the collector of O 15. If a signal is present and doesn’t differ significantly from the waveform picture then the problem exists after 015. Keep dividing until the trouble is found. This technique is·sometimes called, ” partitioning,” “boxing-in-the-trouble,” ” divide and conquer,” or “binary search”; it is mandatory for complex electronic systems, but can save time and energy on almost any electronic device. A blown fuse should only be replaced by one of the proper rating and type. If the fuse blows again, replace it, but place an n meter at the power terminals in place of the supply. Make certain that the+ side of the n meter is connected to the red power wire of the SBE-30CB. Some VOM’s place the – side of the n meter out the red test jack. Observe that D17 protects the unit from a reversed supply. The second harmonic trap (L 12 and CV1) is adjusted at the Factory; field adjustment should not be attempted without proper equipment. Failure of particular channels to work or be on frequency probably indicates a defective crystal. Refer to Table 5-3 SYNTHESIZER MIXING SCHEME. Notice that the same Transmit and Receive crystals are used every fourth channel while each Master crystal is used on four adjacent channels. Check channel selector switch, S2, by swapping crystals.

FIG.5-1 PERFORMANCE VERIFICATION PROCEDURE TRANSMIITER

INITIAL SET – UP

Connect the SBE-30CB to 120 volts AC. Connect a wattmeter, dummy load and oscilloscope to the antenna jack.

STEP 1

Key the transmitter and observe that the wattmeter indicates an output of at least 3 watts and that the RFO meter indicates about the same.

STEP 2

Whistle into microphone with transmitter keyed. Check for 90-100% modulation.

STEP 3

Connect counter to dummy load and check transmit frequencies on channels 1, 2, 3, 4, 8, 12, 16, and

20. (See Table 5-3.)

RECEIVER

INITIAL SET – UP

Connect SBE-30CB to 120 volts AC. Connect RF signal generator to the antenna jack and set to

27.085 MHz 30% – 1 KHz modulation. Set the unit to channel 11. Turn the volume control full clock- wise and the squelch contro l full counterclockwise. Connect an lo ad to external speaker jack, EXT SP and connect AC VTVM to an load. (See Fig ure 5-5. )

STEP 1

Adjust signal generator for 0. 7µ V ou tpu t. Verify that at least 2 VAC appear across the an load.

STEP 2

Increase signal generator output to 200µ V. Rotat e squelch knob fuII clockwise. Receiver shouId squelch.

STEP 3

Adjust signal generator for 100µV. S-METER shou ld read about 9.

FIG.5-2 RECOMMENDED TEST INSTRUMENTS

TEST INSTRUMENT

|

REQUIRED SPECI FICATI ONS

|

-U-SE

Receiver service and alignment.

Transmitter and receiver test and alignment.

Transmitter frequency check and synthesizer troubleshooting.

Measure power output and S.W.R.

Measure audio output.

Audio and modulator tests.

Voltage for servicing.

|

RECOMMENDED IN STRUMENT TYPE

---|---|---|---

R.F. Signal Generator

|

Output frequency: 26.965 to 27.255 MHz.

Output levP.I cali- brated from .1 micro- volts to 500,000 microvolts. Internal modulation capability of 30% minimum at 1 KHz. (Calibrated)

|

Hewlett -PackardModel 606A or B. Wavetek Model 3000.

Oscilloscope| Vertical bandwidth of 25 MHz or greater at 3db point. Triggered sweep capability.| Tektronics Model T932. Tektronics Model 465. Hewlett- Packard Model

180. Phi llips Model PM3260E.

Frequency Counter| Frequency range DC to 30 MHz. Sensitivity: 10mv R.M.S. at 30

MHz. Overall timebase accuracy ±.002%, 6 digit resolution.

| Heath-SchIum burger Model SM128A
Wattmeter| 5 watts full scale into 50 ohm load ±5% accuracy.| Bird Model 43 with type 5A element. (May be term inatedwith antenna load

AC VTVM

|

-40 to +20db range.

| Heath Model IM-21.
Audio Oscillator| 400 Hz to 4000 Hz output: Adjustable level, 0-1 volt output impedence 600 ohm.| Hewlett-Packard Model 204C. Heath Model SG18A.
DC Power Supply| 13.8 volt DC ± 10% at 2 amperes.| Heath Model SP2720 (SBE Mode l SBE-1AC may be used if available.)

TABLE 5-3 sBE-30CB SYNTHESIZER MIXING sCHEME

CH.

|

CH. FREQ.

| MASTER OSC. XTAL FREQ.| TX OSC. XTAL FREQ.| RX OSC.

XTAL FREQ.

---|---|---|---|---
1| 26.965|  | X11 = 10,000| X1 = 9.545
2| 26.975| X5 = 16.965| X12 = 10,010| X2 = 9.555
3| 26.985|  | X13 = 10,020| X3 = 9.565
4| 27.005|  | X14 = 10,040| X4 = 9.585
5| 27.015|  | X11| X1
6| 27.025| X6 = 17.015| X12| X2
7| 27.035|  | X13| X3
8| 27.055|  | X14| X4
9| 27.065|  | X11| X1
10| 27.075| X7 = 17.065| X12| X2
11| 27.085|  | X13| X3
12| 27.105|  | X14| X4
13| 27. 115|  | X11| X1
14| 27.125| X8= 17.115| X12| X2
15| 27.135|  | X13| X3
16| 27.155|  | X14| X4
17| 27.165|  | X11| X1
18| 27.175| X9 = 17.165| X12| X2
19| 27.185|  | X13| X3
20| 27.205|  | X14| X4
21| 27.215|  | X11| X1
22| 27.225| X10= 17.215| X12| X2
23| 27.255|  | X14| X4

RECEI VE
(CH FREQ) – (M.O. FREQ ) – (RX OSC F REQ ) = 455 KHz
TRANSMIT
(M.O. FREQ)+ (TX OSC FREO ) = (CH FREO )

FIG.54 TRANSMITTER TEST CONNECTION FIG. 55 RECEIVER TEST CONNECTION FIG. 5-6 RECEIVER ALIGNMENT PROCEDURE

INITIAL SET-UP

Connect an AC VTVM across the speaker or au load plugged into J3 EXT SP. Connect the RF signal generator to the antenna jack, set to 27.085 MHz 30% · 1 KHz modulation. Set the Channel Select SW to channel 11. Turn the squelch control full counterclockwise and the volume control full clockwise.

STEP 1

Adjust the RF output level of the signal generator to a level sufficient to produce about 2 VAC on the AC VTVM. Adjust Tl , T2, L1, L2, T3, T4 and T5  for maximum indications on  the AC  VTVM. If  at any time during the alignment procedure the audio level increases to more than 4 VAC, reduce the generator output level. Repeat adjustment until  0.7  µV  RF  signal produces about  2 VAC  on the AC VTVM.

STEP 2

Turn squelch control full clockwise. Increase the RF signal to 300µV. Squelch should break. If squelch fails to break, adjust VA3 to break squelch.

STEP3

Turn squelch control full counterclockwise. Set RF signal generator to  10 MHz. Adjust 10 MHz t rap L9 for minimum indication on the AC VTVM.

STEP 4

Set RF signal generator to 100 µVat 27.085 MHz. Adjust VR5 to make the S METER indicate 9.

TABLE 57 AGC VOLTAGES versus RF INPUT LEVEL INPUT LEVEL VOLTAGES (2)

1. Channel Frequency at Antenna Jack
2. Measured with 10M2 input at junction R 19 and C25.

FIG. 5-8   ALIGNMENT LAYOUT TABLE 59 RECEIVER INJECTION VOLTAGES
All injection voltages are at 30%- 1 KHz modulation at the specified frequency fed through a.01 MFD capacitor, and should produce at least 2 VAC audio output measured across the speaker or across an 82 load connected at EXT SP J2. Typical audio output voltages are given.

INJECTION

POINT

| INJECTION

LEVEL

|

FREQUENCY

| AUDIO OUTPUT
---|---|---|---

ANT JACK J1

|

1µV

|

Channel Freq.

|

4.6V

Base of 04 – CP1 *| 1µV| Channel Freq.| 4.0V
Base of 05 – CP2| 10µV| Channel Fr eq.| 2.8V
Base of 06 – CP3| 100µV| 10.02 MHz| 3.4V
Base of 07 – CP4| 300µV| 455 MHz| 5.0V
Base of 08 – CPS| 3000µV| 455 MHz| 2.5V

FIG. 5-10 TRANSMITTER ALIGNMENT PROCEDURE

INITIAL SET- UP

Connect the transceiver to 120 volts AC. Connect an audio oscillator to the MIC input, a wattmeter and dummy load to the antenna jack, an oscilloscope to the dummy load, and set the channel selector to  channel 11. (See F igure 5-5.)

STEP 1

|

With no modulation, key the transmitter and adjust L4, L6, T8, T9, and T10 for maximum wattmeter indication.

STEP 2

|

Alternately, switch channel selector to channels 1 and 23. Adjust L4 and T8 for the least change in watt-meter indication.

STEP 3

|

Adjust L8 and L 10 for maximum wattmeter indication not to exceed 4 watts.

STEP4

|

Set the audio oscillator to 1 KHz. Adjust output level for about 80% modulation.  While  observing scope, adjust L8 and L 10 for best modulation symmetry.

STEP 5

|

Adjust the audio oscillator’s level for 50% modulation. Read level on AC  VTVM and increase level until the AC VTVM reads 8 times as great (about 18db). Adjust VR4 for 100% modulation.

STEP 6

|

Remove audio oscillator. Adjust VR6 until RFO METER reads the same as wattmeter.

FIG. 5-11 TRANSMITTER ALIGNMENT WAVEFORMS FIG. 5-13 COMPONENT LAYOUT

SBE-30CB TRINIDAD II PARTS LIST

SYMBOL                         DESCRIPTION                          PART

25

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