>....... the plate tune vacuum cap has about 200 little
>pitts in the internal element. I assume it was way out of tune a few
>times ...
I wouldn't bet on it.
>...and once it became pitted the arcs were easier to get started.
>Anyone know if this item is easly found? The book said it was a 400pf at
>7500 volts.
Jennings will sell you one [408 292 4025]. However, I doubt that a new
unit will correct the reason that the original cap. was arcing.
> The next item of interest was the band switch. It looks like the
>contacts are still making but some arcing has taken place. Looks like it
>might have been on 10 meters at the time???
Arcing at the 10m contacts is usually an indication of intermittent vhf
oscillation--a condition which Messrs. Erhorn and Rauch say can not
happen. If it were my amp., I would conduct a sputtered gold test on the
8877 with a high-pot tester. I have tested a number of 8877s that died in
77s due to gold sputtering. I currently have a decapitated one sitting
on my desk. It might be a good idea to decrease the vhf-Rp of the
anode's vhf parasitic suppressor.
>I might as well replace that
>too.
...snip
> It has QSK with a vacuum relay in the output.
however, the 26v vacuum relay closes too slow for some modern radios.
The speedup-solution is to raise the relay's coil source from 50v to at
least100v and increase the series R that limits the relay's coil current
to 80mA.
Rich---
R. L. Measures, 805-386-3734, AG6K
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