[Milsurplus] PA Tank Circuit Padding Capacitors

[AKLDGUY .]

You say, "Padding across the coil..." so I assume you want to connect the
capacitor that way and not from plate to ground (which would double the
capacitor's voltage rating because the DC plate voltage would then be
across it too).

So with the capacitor across the coil (not subjected to B+), the peak RF
voltage across it is approximately the plate voltage. If this final stage
is AM modulated to 100%, the figure must be doubled, so the rating must be
at least 700V, and should be conservative, since the voltage rises steeply
when the load is not matched during tuneup.

This info is based on information in the ARRL Handbook, 1963, p.167.
I would go with a ceramic capacitor, 3 KV rating.

73 de Neil ZL1ANM


On Tue, Aug 2, 2016 at 12:15 AM, David Stinson <arc5 at ix.netcom.com> wrote:

> Given: Series-feed Triode PA tank with link-coupled output.
> 350 VDC B+, about 9 W out on 75 Meters.
> Padding across the tank coil with a 50 pFd doorknob was successful in
> lowering its resonant point, but space is severely restricted and doorknobs
> can be expensive.  *Rewinding the coil is not an option.*
>
> What other types and specifications of  available
> capacitors would you recommend for this service?
>
> TNX OM ES 73 DE Dave AB5S
>
> ______________________________________________________________
> Milsurplus mailing list
> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Milsurplus at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/milsurplus/attachments/20160802/30477914/attachment.html>