Some channels are off frequency by different amounts. (Refer to preliminary
check # 5)
*Common faults:
• Improper diode programming.
• Solder shorts between traces. (There’re a lot of traces between U6
and the diode matrix!)
Transmit Section Faults:
(manual pages 25 - 26, 118 - 123)
1. No power output.
a. Check for proper VCO frequency.
b. Check +8T and +12V to the`transmit Buffer, Driver, and Final
stages.
c. Ensure D7 is forward biased. (approx. 7.2 VDC at junction of L17 &
R54)
d. Double check all components in transmit section for proper value
and placement.
e. Check for heat on Q9 and Q8. (If they’re warm, chances are they’re
working)
*Common faults:
• Coils touching the board.
• Solder shorts between components.
• Solder short on Q8 base to ground.
2. Low Output Power. (We see 3-5 watts normally. If your figures are
within 20%, consider this ok.)
a. Ensure DC input to the transceiver is a full 13.8 VDC. (If your lead
wires are too long, they could be dropping excess voltage.) Check
for proper voltage on the board, not
at the power supply.
b. Ensure +8T is a full 8VDC. (This is the supply voltage for the
transmit Buffer.)
c. Try adjusting the coils slightly, and then retuning for maximum
power output. (L12, L13, L16, and L22 are purposely designed to
have extra inductance so you can peak the power output by
spreading the coils.)
*Common faults:
• Low supply voltage.
• Improper tuning.
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