[AMPS] PS diode equalizing

[Rich Measures]

>
>Peter Chadwick wrote:
>> 
>> I use resistors across the diodes, with no capacitors. With 1kV diodes, I
>> use two 500volt resistors in series, although that's probably 'belt and
>> braces'. If I was using capacitors, they'd be .01 microfarad 1kV working
>> micas or plastic film, not disc ceramic, because of temp co and tolerance.
>> I've never had hash caused by the diodes switching abruptly, either. With
>> 1N5400 series, they're relatively slow, so I wouldn't expect it.
>
>30-odd years ago, I worked at a BC station.  We had a 5kw FM transmitter 
>whose
>power supply contained boards made of many, many 400 piv diodes.  They were
>paralled with (I think 470K) resistors.  We lost quite a number of boards
>(sounded like a machine gun when they went).  We tried to match resistor 
values,
>etc. to no avail.  At some point, someone suggested that we use .001 uf
>capacitors instead, and after that we had no further problems.
>
>So far, the advice I've received has included 1) don't put anything across the
>diodes, 2) put only resistors across the diodes, 3) put only capacitors across
>the diodes.  I'm leaning to the capacitors, because of my ancient experience.
>
€  Manufacturers of encapsulated multi-diode stacks used to use equalizer 
resistors and capacitors.  They apparently stopped the practice over 15 
years ago.  

-  later, Vic


Rich...

R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  


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