Thanks, Ken.
You're right about using the resistors to equalize the drops across the
older diodes, and (in some cases) the filter caps.
In this case, though, it's just about something I heard from Bill Orr (I
think) years ago about "switching noise" or "white noise" from the
diodes showing up in the receiver. I was curious about it, which
prompted my original mail.
73,
Jim N7CXI
On 10/30/2010 1:46 PM, Ken Brown wrote:
>
>> I'm getting ready to lay out the HV rectifier board for my YC156
>> project, and it occurs to me to wonder if anyone has ever really heard
>> HV rectifier "white noise" in the receiver? It would be simpler to
>> forget about the per-diode bypass caps and just bypass the output as
>> it leaves the board. The supply will be housed in a separate cabinet
>> from the RF deck, but connected of course with bypassed leads for HV,
>> (SHV connectors) 110VAC and control signals.
> I thought the reason for capacitors and resistors paralleled with the
> series diodes was to help equalize the voltage division across the
> diodes, and reduce the chances of an unequal voltage division, exceeding
> the voltage rating of one of the diodes. I did not think it was for
> noise reduction. I had also heard that it was more important with
> earlier manufactured diodes, due to lower voltage ratings and not quite
> as good matching from one diode to another. With more modern production
> diodes the voltage division tended to be more equal, reducing the need
> for the resistors and capacitors.
>
> DE N6KB
>
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