[Amps] Jennings Vacuum Variable Capacitor

rlm
Thu Oct 30 04:50:15 EST 2003


On Wednesday, October 29, 2003, at 09:40  AM, Mark Toussaint wrote:

> Hi;
>
> I'm converting an old sb-220 to work on 50mhz. I need
> a low value tune cap and want to use a Jennings vacuum
> variable of 2-30pf, rating of 5kV or 7.5kV. Does
> anybody have one or know of a good source for these
> that won't break the bank ?  I know I'll need a low
> value of C for the tune, any other thought's or
> suggestions ?

*** Methinks:
1.   Put the Tune-C close to the anodes and use the stock Tune-C for 
the 6m Load-C.
2.  Use no parasitic suppressor whatsoever.
3. Make the leads from the anodes to the Tune-C out of stainless-steel 
shim-stock, or Ni-Cr.  1/4" wide conductors should be able to carry the 
current.  [advertisement:  We sell this stuff for 50-cents per foot]
4.  Build the 6m tuned input with a Q of c. 3 and mount it next to the 
tube sockets.
5.  Add enough shunt-to-gnd C at the relay to tune out its own XL on 6m.
6.  Use 1/2" Cu plumbing tubing for the tank L.

good luck

>
> Thanks in advance, Mark
>
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Rich Measures, AG6K, 805.386.3734.  www.somis.org/



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