Bill
I apologize for not contacting TenTec for you this week. I was called out of
town and just returned. However I've been analyzing the Century 22 problem
(and recalling the schematic from memory) and let's try this:
The problem at high power and not low power indicates that probably your
keying circuit is OK. Let's check the driver circuit (my first choice) and
the final amp circuit (2nd choice).
It appears that the circuit in question (start with driver) is not getting
enough current, and working only off a charged electrolytic capacitor until
drained (high power, quickly drained, low power slower drain and barely
sufficient current to maintain operation), then the limited power into the
circuit is pulsating on hi power trying to properly supply the circuit. I
would follow the 12 volt line thru the driver circuit, testing voltage on
key-down on driver collectors. It could be a bad series resistor, bad solder
joint, or bad connector. Transistors, unlike tubes, are usually not prone to
get soft and "die away" on key down.
Voltage checks (with RF probe) should be done on driver bases. If all fails
to show problems on the driver circuit, then do the same on the final amp
circuit.
FINALLY, I do not remember if the driver circuit has a trim-pot to adjust the
pre-driver drive to the driver. If so, that's my first item to clean and
insure operation.
Keep us posted on your findings.
Thanks
Bill, K5BDZ
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