I'm still having some issues with this L-75 I'm working on. I lit it off
after replacing the filter caps and pcb. Two issues have shown up that I'm
trying to work out. I don't get any power out on 160; about 10 watts on 80;
100 on 40 and ~500 on 20. The dip on 20M is very sharp and tight which tells
me the Q has increased drastically there. Plate current goes up and down
with drive, (my TS-940 shows acceptable SWR from the input circuit, with no
power fold-back). I'm beginning to think that the coupling caps, C30, C31,
might be the culprits. They are 750 uuF at 4KV. One of the questions is it
acceptable to replace these two disc ceramics with a single 1500 uuf 6KV
one?
The other issue is I toasted the diode in the 'Relative Power'
circuitry. Now this may be as a result of the first issue. But it is tied
directly to the loading cap in the output tank circuit.
Any help is greatly appreciated.
Thanks.
Mod-U-Lator,
Mike(y)
W3SLK
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