[Amps] .01uf caps across diodes ?

[Jim Barber]

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
concern.
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...

73,
Jim N7CXI

On Tue, Nov 29, 2022 at 11:28 AM jim.thom jim.thom at telus.net <
jim.thom at telus.net> 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
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>