Realisitic
TRC-476
Documentation Project
CBTricks.com
PLL & Transmitter Alignment
Phase Locked Loop and CPU Section
Test
Equipment Required
a. Frequency Counter
b. DC Power Supply (13.8 Volt. 3 Amp.)
c. DC Voltmeter
d. Oscilloscope
Alignment Procedure
|
Step |
Setting |
Connection |
Adjust |
Adjust for |
|
1 |
Frequency
adjustment: |
Frequency counter to output pin 20 of IC501 |
C528 |
10.240MHz ± 100Hz |
|
2 |
RX
VCO voltage adjustment: |
Connect DC voltmeter between R527 and R531 |
L501 |
2V |
|
3 |
TX
VCO voltage adjustment: |
Connect DC voltmeter between R527 and R531 |
L501 |
Indication on DC voltmeter must be 1.5-2.5 Volt. If DC voltmeter does not indicate 1.5-2.5 volt, readjust L501. |
|
4 |
CPU
IC Voltage check: |
Connect DC voltmeter to pin 24 of IC501 |
|
Indication on DC voltmeter must be 5- 6V volt. |
|
5 |
CPU
frequency check: |
Connect oscilloscope to pin 8 and 9 of IC501 |
|
Check for 160 Hz of square waveform on the oscilloscope |
Transmitter Section
Test Equipment Required
| a. RF Powermeter (RF SSVM) | f. DC Power Supply (13.8 Volt, 3 Amp.) |
| b. 50 ohm load (non-inductive) | g. Spectrum Analyzer |
| c. RF Attenuator | h. Frequency Counter |
| d. Oscilloscope | i. Coupler |
| e. Audio Generator | j. Dummy Load |
Alignment procedure
|
Step |
Setting |
Connection |
Adjust |
Adjust for |
|
1 |
RF
Driver stage: |
Connect oscilloscope to base of Q302 |
L302 |
Maximum waveform on the oscilloscope. |
|
2 |
RF
Power stage: |
Connect dummy load and RF powermeter to the EXT-ANT. Jack on the set |
L303
|
Maximum indication on the powermeter (4 watts). If indication is not in 4 watts range, readjust L301, L302, L303, L304, L305, L306 |
|
3 |
Second
harmonic check: |
Connect RF powermeter with dummy load to spectrum analyzer through coupler/ -40dB attenuator to EXT-ANT. Jack on the set |
|
At no modulation, compare the level of fundamental frequency to the level of harmonic frequency. Suppression of the 2nd harmonic frequency level must be lower than - 60dB. Check for the other channels. |
|
4 |
Frequency
check: |
Connect dummy load and frequency counter through coupler to RF powermeter. Connect RF powermeter to EXT-ANT jack on the set. |
C528 |
Make sure that the indication of the transmitter frequency is 27.185MHz ± 300Hz on the frequency counter. |
|
5 |
TX
Power LED adjustment: |
Connect dummy load and oscilloscope through coupler to RF powermeter. Connect RF powermeter to EXT-ANT Jack on the set |
RV202 |
Adjust until the 3rd LED light up at 4 watts RF output power. |
Disclaimer: Although the greatest care has been taken while compiling these documents,
we cannot guarantee that the instructions will work on every radio presented.