User's Manual

4-2
TABLE 4-1 TROUBLESHOOTING HINTS (Continued)
5. Relays A9K1, A9K2, and A9K3 close at turn
on, but line fuses blow.
A] High voltage shorted at crowbar or
elsewhere.
B] Shorted tube.
C] Leaky electrolytics in high voltage supply.
6. Amplifier won’t drive, zero grid and plate
current, high input SWR .
A] Defective cable from transceiver to
amplifier.
B] Input relay A4K2 on 81951 SWR board
defective.
C] Input filter A7 or A8 on 81946 Input
Matching board (A6) loose or damaged.
7. Grid overdrive LED lights with no drive. A] A10Q7 on 81950 Screen Supply shorted or
leaky.
B] Shorted or leaky tube.
8. Screen overdrive LED lights with no drive. A] A10R23 on 81950 Screen Supply open or
increased in value.
B] Low or no high voltage. TURN OFF THE
AMPLIFIER IMMEDIATELY.
9. Amplifier difficult to drive, little or no output,
high plate current (may be accompanied by a
“frying sound”).
A] Band switch in wrong position.
B] Excessively high load SWR.
C] Defective output relay A4K1 on 81951
SWR board.
D] Arcing in tank circuit or antenna feed
line.
10. Excessive plate current in receive mode. A] Defective bias circuit, 81950 board (A10).
B] Shorted grid /cathode in tube.
11. Transceiver does not key using key-in/key-
out loop.
A] Key-in and key-out lines reversed at
amplifier or at transceiver.
B] Defective key line cables.
C] Defective relay control circuit on 81949
QSK board (A11).
12. Transceiver stays keyed in receive mode.
May be accompanied by loss of receive signal.
A] Relay A4K1 on 81951 SWR board stuck.
B] Shorted key-in or key-out cable.
C] Defective relay control circuit on 81949
QSK board (A11).