[Heathkit] SB-610 Selenium Diodes - caps across silicon diodes.

[Garey Barrell]

Hi Mike!

But ....  what's SAFE about putting a 1 or 2W resistor rated at 500V 
across a diode that sees 800-900 PIV?   Or the roughly 8 Watts  _peak_  
dissipation in those same resistors?  The caps don't hurt anything,  _AS 
LONG AS_  they are rated for at least 1000VDC.

73, Garey - K4OAH
Atlanta

Drake C-Line Service Manual
<http://www.k4oah.com> 



Mike,W8KRR wrote:

> Still say "better safe than -"
> Mike
>
> Garey Barrell wrote:
>
>> Pre 80's (roughly) diodes were not as consistent from unit to unit as 
>> they are today.  Parallel resistors and capacitors were used in an 
>> attempt to "force" equal distribution of static and dynamic voltages 
>> across series connected devices even though one might have 
>> considerably lower reverse current leakage, etc.
>>
>> Improvements in manufacturing techniques and materials have resulted 
>> in devices that are near clones of each other and so have very 
>> closely matched forward and reverse characteristics.
>>
>> 73, Garey - K4OAH
>> Atlanta
>>
>> Drake C-Line Service Manual
>> <http://www.k4oah.com>
>>
>>
>> Tom NØJMY - AAR7FV wrote:
>>
>>> ----- Original Message ----- From: "Garey Barrell" 
>>> <k4oah at mindspring.com>
>>>
>>>> None of my design references for power supplies recommends 
>>>> bypassing of individual diodes
>>>
>>>
>>>
>>>
>>> <snip>
>>>
>>> I remember it was the recommended practice in the ARRL handbook at 
>>> least until the mid-80's.  Things have changed since then, of 
>>> course, and I haven't checked any of the more recent editions. I 
>>> would be interested to see when and if (and, of course,  if so, then 
>>> *why*) they dropped this recommendation.
>>>
>>> 73,
>>> Tom
>>>
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>
>