You have to know the value of the cap to know what the current value is. 7
amps at 420 volts for what value of capacitance?
My guess this is for the entire load cap that you have. What is the RF
current through a 100 Pf cap? Or a 250 Pf cap? Keep the value low enough and
parallel enough caps and you don't need a cap with that high of a current
capacity. Alpha uses at least 10 small caps for the load padder.
73
Jim W7RY
----- Original Message -----
From: "Steve Flood" <kk7uv@bresnan.net>
To: <amps@contesting.com>; <rfamplifiers@yahoogroups.com>
Sent: Sunday, January 18, 2009 4:12 PM
Subject: Re: [Amps] plate bypass caps
>I have quite a few of the old-style transmitting mica caps (C-D, Sangamo,
> Solar, etc.). Are these okay to use in a nearly-legal-limit amp for
> either
> plate-choke bypassing, or antenna load padders? Some of these are marked
> for 2500 working volts. I don't have a hi-pot to check them out (that's
> another project in the que).
>
> RF Parts carries them - they are items CM45, CM55, CM60 on their "Mica Cap
> Comparison" link.
>
> My setup is 2700v B+, plate load about 2500 ohms. The PI-EL program shows
> about 420 volts and 7 amps at the antenna load variable cap. In case I
> need
> a little less loading om 160m, I'd like to pad it with 500pF.
>
> Steve KK7UV
>
>
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>
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