Mike -
OK. Well, 90W is also pretty low. You should see at least 130W output
in TUNE on the lower bands, and 110 or so on 10M with a good set of finals.
The drive scheme is different on CW and TUNE, so lets out most of the
low-level trouble spots.
So aside from a much less likely coupling capacitor or switch failure,
the final tubes are likely the problem. You may have been running one
tube, and so overloading it at 90W and it finally gave up the ghost too!
You didn't answer the idle current question, so I assume it is set to 70
mA per the manual, which indicates the tubes are ok at DC anyway, and
the DC voltages are at least near where they should be. This also
indicates that the relay and associated circuitry are ok.
I believe you said you had subbed the other tubes, so that pretty well
leaves you with the finals!
Be sure and let us know what you find!
73, Garey - K4OAH
Louisville, KY
Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
<www.k4oah.com>
Mike Williams wrote:
Hello Gary,
thanks for the tips and the tube is a 6AU6A, not a 6UA8, my typo; I
checked R44, R53, R54, and R59 and all ohm out OK; CR19 also is OK by an
in circuit diode check. Did not see anything obvious while scanning the
circuitry, the T4XC was putting out around 90 watts on all bands prior
to the sudden drop of output down to 30 watts.
73 de W4DL Mike
ex AK7P * WA9SWF * WN9SWF
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