>
>> One can not use an "it was off value, so it MUST have been a VHF
>> parasitic" as proof of the cause of damage. Many things, including
>> temperature and time, cause carbon resistors to go off value.
>
>I have an old SB-200 on the bench now that has the original factory
>supplied tubes. This amp has been in constant use all these years.
>Out of curiosity, I measured the two 47 ohm Rsupp stock Heath
>suppressor resistors. They both had changed value identically to
>59 ohms. No signs of heating; the color bands are bright as new.
>Talking to the owner, this amp has never had any glitches of any
>kind. One of the filter caps in the HVPS has just quietly "passed away"
>and lowered the HV from 2400 to 1650.
>
>I strongly suggest all owners of suppressors with carbon resistors
>replace them with more modern units during the next annual "cleaning
>and oiling." A very cheap and easy PM project.
In a VHF suppressor, Less Rp means less VHF gain. Increasing the
inductance of L-supp decreases Rp. Making L-supp out of resistance wire
decreases Rp by around 60%. //See Wes' measurements/
end
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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