[Amps] 2nd grid resistor blow Ameritron AMP 811H

[R.Measures]

On Aug 15, 2005, at 10:47 AM, Vic K2VCO wrote:

> D Pipes wrote:
>
>> Thanks for the reply. I do have an added question. Would I be seeing
>> parasitic conditions before and without any RF ye? This has happened 
>> only
>> when i switch the amp on (power switch) still in standby and no RF 
>> load
>> applied as yet just at start up on the power switch? thanks
>
> I doubt that this problem is caused by a parasitic.  I certainly would
> not make a categorical statement like 'you are getting a parasitic
> oscillation...'.
>
> It sounds like, more than anything else, a tube defect.  Yes, it is 
> very
> mysterious that it happened twice in the same place.

To find out if it was a parasite or not, measure the ohms of the 
parasitic suppressor R on the tube that blew it's grid R.  If the ohms 
are still within tolerance, it was likely not a parasite.
-   I have observed that serious parasites in 811s can put so much EMF 
on the filament, that it shatters into pieces and falls to the bottom 
of the glass envelope.
>
>
> -- 
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco
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>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org