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Re: [Amps] .01uf caps across diodes ?

To: "jim.thom" <>
Subject: Re: [Amps] .01uf caps across diodes ?
From: Jim Barber <>
Date: Tue, 29 Nov 2022 12:07:19 -0800
List-post: <>
I've never seen a HV bridge fail because of "switching transients". Do they
exist?  I don't know but if they do I have no evidence they're of critical
I have, however seen bridge diodes and even plate bypass caps fry because
of primary transient surges. A local 2x 3CX800 amp failed from that
exact issue quite recently.

A hefty MOV from each leg of the primary power to the neutral would seem to
me to be a much better investment - as would
considering *potential* peak voltages when selecting plate/meter/whatever
HV bypass caps .

My .02 only, adjust for transient inflation...


On Tue, Nov 29, 2022 at 11:28 AM jim.thom <> wrote:

> What's the consensus on wiring .01uf disc caps across diodes in a HV supply
> ?
> W8JI sez they are required, and used in ameritron amps....and used to
> eliminate switching transients.
> Some say the caps are required to meet emc specs on commercial gear.
> I can't see how anything can get past the HV fitter caps.
> KM1H also uses caps across diodes.  He also used another method, with a
> .01uf cap across an entire series string of diodes, like a .01uf @ 5 kv
> type.
> Orr's books recommend caps across diodes... to eliminate noise on TX on
> ssb. .
> Are they required...or not ?
> Jim  VE7RF
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