On Apr 6, 2005, at 7:19 PM, Joe Subich, K4IK wrote:
>
>
>> Rich writes:
>>
>> Joe -- Are you saying that Eimac's 8877 design team told you they did
>> not choose to use Eimac's grid-grounding collet during testing of the
>> 8877?
>
> 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?
> and resolving stupid
> layout issues (like stray coupling - e.g., unbypassed control wiring -
> from the output to the input). This also applied to larger "tubes
> with handles" designed for applications like VHF TV visual service.
>
> This does not apply to tubes with long internal grid leads (e.g. 811A,
> 572B, etc.). It is impossible to "properly ground" the grid of tubes
> like that ... then other means of eliminating parasitics may be needed.
>
> 73,
>
> ... Joe, K4IK
>
>
>
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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