On Jul 16, 2006, at 12:24 AM, S. J. Blackwell wrote:
> Rich,
> I have seen your comments about Alpha and the use of the ceramic
> disc padders in the output tank for some years now. Would the burr
> under your saddle be relieved if these were multiple HV ,relatively
> low pF, NPO caps in parallel?
NPØs or N750s would do the job well. Bypass caps don't.
> If not, why not? I am using 16 ea 50pF, 4KV, NPO padders on the 160
> load cap of my 8877 amp.
Excellent.
> It seems to work quite well. I am not worried at all, even after
> seeing your comments for some years now. Oh yes, my Alpha 89 still
> seems to be working quite well (with original tubes), even after
> many years.
>
> Your comment about the carbon resistors seems approiate, however
> the entire comment seemed rather graturitous as the subject was
> about turning the the amps on and off and concerns about filament
> life.
The tubes used in an Alpha 89 do not have filaments, they have
heaters. Only tubes that have thoriated tungsten filaments have
inrush current concerns.
> By the way, just to keep on topic, the Alpha has a low value
> resistance in series with the filament that would limit the initial
> cold current to some extent. Oh yes, I am aware of surge, no surge
> thoughts re indirecly heated cathodes.
What is the resistance in ohms, Sam?
end,4:55am, 7/16/06
> 73,
> Sam W5LU
>
>
>
>>> Rob -- This may have something to do with their decision to use
>> carbon comp resistors to equalize the voltage across the HV filter
>> caps, to operate these resistors above the max V rating, and their
>> decision to use less expensive coupling caps for tuned circuit padder
>> caps.
>> end 5:54AM. 15 July 2006
>> >
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>>
>> R L MEASURES, AG6K. 805-386-3734
>> r@somis.org
>>
>>
>>
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>
R L MEASURES, AG6K. 805-386-3734
r@somis.org
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