Hi Dick,
<snip>
> One of the questions I have is about the Plate Coupling Cap
> value. I see values of anywhere from 100 pF to 1,000 pF used.
<snip>
A good "rule of thumb" is 4X the tune capacitance. The value is not at all
critical. 100pF, or thereabouts, will be fine for 6 meters with your pair of
3-500's.
There are some extra caveats on the higher frequencies where the plate output
capacitance becomes a significant portion of the tune cap. The coupling cap
must now carry a considerable portion of the circulating current; an NPO
ceramic part is good for this.
The best choice would be a vacuum cap. One from the Jennings JCSF series
would be great. There may also be some physcially larger 100pF WW2 vintage GE
& Western Electric parts still extant. These are rated 5KV but typically test
way over 10KV
Using a grossly overvalued part is proscribed. At some point enough stray
inductance will accumulate to cause... problems.
73 & Good morning,
Marv WC6W
http://wc6w.50webs.com/
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