[R-390] Bypass capacitors, R390 and SP-600 [WAS: saga continues...]

[James A. (Andy) Moorer]

  Do you have any opinion on the composition of the ceramics? Should 
they be NPO, or can they be inexpensive Z5U?

-A

On 9/12/2010 1:56 AM, 2002tii wrote:
> Roger wrote:
>
>> Some 300 Volt items will work well. Move up one decimal point .01 to .1 and
>> such. You just get some more by pass. Cost is not the issue any more. Size
>> is not the issue any more. Exact part number is not an issue any more. You
>> need a good cap that filter out more than it lets in or does not filter out.
> Going up in value with film bypass caps is probably not a good idea,
> because it moves the self-resonant frequency of the caps down (and
> unfortunately, modern wound film caps do not have appreciably lower
> inductance than their forbears).  As we have discussed here before,
> however, you can get MUCH BETTER bypassing performance by switching
> from film caps to disk ceramics, owing to their much higher
> self-resonant frequency.  In this case, going up in value is OK (but
> definitely not necessary).  As I have said before, buy yourself a
> large bag of NEW .02 or .05 uF/1000 V disk ceramics and use them for
> all tube radio bypassing applications -- you will never be
> sorry.  Keep all capacitor leads as short as possible -- as Roger
> noted, feel free to use a different ground point to achieve
> this.  And use spaghetti tubing as necessary to insulate the leads.
>


-- 
James A. (Andy) Moorer
www.jamminpower.com