[Amps] a common topic here tspa
Ian White G3SEK
G3SEK at ifwtech.co.uk
Thu Apr 7 06:26:59 EDT 2005
R. Measures wrote:
>> No, I'm simply saying that the Eimac tube guys that I knew and worked
>> with said a lot of what passes for "truth" is a bunch of nonsense.
>> In their experience, every case of "parasitic problems" in 8877 amps
>> could be resolved by properly grounding the grid
>
>Did the 8877 design team use improper grid-grounding that resulted in
>the "oscillation condition" they observed that caused gold to evaporate
>from the grid of the DUT?
>
That seems to be conflating two different stories, on the basis of
information from an individual Eimac employee which the company
subsequently said was incorrect.
The "oscillation condition" in question was not a VHF parasitic as we
know it, but can only arise in extremely large tubes that are big enough
to have their own internal VHF resonances.
What causes gold evaporation is overheating - that much seems obvious.
What caused the overheating in any particular case is entirely open to
question.
--
73 from Ian G3SEK
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