[Amps] .01uf caps across diodes ?

[Alek Petkovic]

Yes. That is the reason I thought the caps are there. To stop noise in 
the receiver.

Someone, on this forum or the other one, a year or three ago, said that 
the noise was real and that the capacitors fixed it.

I have never bothered with the caps and my location is so noisy, I don't 
think I'd hear any diode noise anyway.

73, Alek VK6APK

On 14/12/2022 9:38 am, Tim Duffy wrote:
> My question around the .01 uF caps on the HV rectifier diodes was not so much about diode preservation or protection - I am curious about any possible RFI generation from the HV diodes or more importantly any mixing products from RF (multiple transmitters). So a .01 uF across the HV diodes or .01 uFs to B minus on the diodes that might "keep things quiet" is my curiosity.
>
> 73,
> Tim K3LR
>
> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Ron W4BIN
> Sent: Tuesday, December 13, 2022 7:53 PM
> To: amp
> Subject: Re: [Amps] .01uf caps across diodes ?
>
>      MU 4CX250B wrote:
>
>> An interesting point, Steve. If I understand you, you’re saying that
>> if a modern diode in a series string approaches reverse breakdown, it
>> will start to conduct, thus shifting its overload voltage to other
>> diodes in the string. Before the advent of controlled avalanche
>> diodes, however, an overloaded diode would just short circuit, thus
>> permanently shifting its voltage to the remaining diodes in the
>> string. This process, once started, would likely lead to the
>> destruction of the entire string.  To me, the takeaway message is that
>     No that has never been the case, "controlled avalanche diodes" of a
> particular type all avalanche at the same Voltage.*
> Otherwise the lowest reverse Voltage device could avalanche and present a
> very low resistance, (causing an increase in reverse Voltage across the
> rest)
> then the next lowest Voltage device could avalanche until they would all
> avalanche at which time, the current would destroy most until one "blows
> open"
> ending the catastrophe.
>
>     Zener diodes below about 6.2 Volts are true Zener diodes, above about
> 6.8
> Volts are "controlled avalanche diodes" and as long as they are conducting
> reverse current less than Imax they are not harmed.
>
>    * in our high Voltage operations a tighter grouping of avalanche Voltages
> can be maintained by buying in lots like of 50 or 100 and keeping the
> batches separate and constructing strings all from the same batch.
>
>> there’s little to be gained these days by adding .01uF caps to each
>> diode. This is a helpful explanation, Steve. Thanks!