[AMPS] Mount pi-net capacitors vertically

Tom Rauch W8JI@contesting.com
Mon, 18 Sep 2000 08:44:55 -0400

> The biggest difficulty is making sure that the connection to the front of
> the vacuum variable capacitor is electrically good. I use an electrolytic
> capacitor clamp to hold the cap, and a piece of thin copper sheet under
> the clamp to make the connection. Because of inductance, this might not be
> too good at VHF though, and possibly I need to make a proper collett out
> of aluminium - or brass - for the new amp. However, in the antenna tuner
> for 160 and 80, there's no problem.

I use a sub-front panel and mount the capacitors directly to it. The 
input and control circuits go between the sub-front and the front.

That way I can work on the input or control/bias/metering circuits 
without any danger from having HV on and without disrupting airflow.

If I have occasion to use capacitors that aren't drilled and tapped on 
the front, I bore an interference fit hole for the capacitor's front in a 
small square of thick aluminum plate. I slot the plate from one side 
of the hole out so I can use a long screw to squeeze the plate 
against the capacitor.
I've never found any advantage to vertical mounting here in layouts, 
but that probably because I use a sub-front panel.

73, Tom W8JI

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