[AMPS] parasitic suppressors

[Rich Measures]

>At 08:29 AM 12/11/97 -0800, you wrote:
>
>>
>>The grid of an 8877 is rated at 25W dissipation.  The grid of a 3-500Z is 
>>rated at 20W dissipation.  The "in excess of four Joules will permanently 
>>damage" statement seems to be questionable.  . 
>>[note:  a Joule (J) is 1 watt for 1 second}  
>>-  For a tube whose grid is rated at 1W, 4J might possibly cause damage.  
>>For a tube whose grid is rated at 25W, how could 4J damage the grid?  I 
>>find it hard to believe that a legitimate power grid tube engineer wrote 
>>such a statement, Phil.  Do you know the name of the person who wrote it? 
... ... ...
>The paper is unsigned. I got it along with a stack of Eimac Service 
>Bulletins.
>I got them from Reid Brandon. 

Interesting.  This is the fellow who seemed to be unaware of the QST 
articles on parasitics. (pages 72 -75 of 9/94 QST}
-   After I telephoned Eimac and was told that a certain ex-employee was 
never an "R+D Engineering Manager" -- as Mr. Rauch had claimed, I decided 
it might be a good idea check out another of Mr. Rauch's Eimac-pals.  I 
telephoned Eimac's CA facility and was told that Mr. Brandon was not 
employed in Eimac's Engineering Department.  

> "You might ask him who wrote the paper. It did
>state that the voltage involved in the glitch through a tube is 50 volts. 

This seems reasonable.  However, the vanishing gas theorum doesn't.  

>That means that in a 4000 volt supply, the glitch resistor will have 3950 
volts 
>accross it. 

True enough, Phil, however, there could easily be hundreds of volts total 
drop across the ohms in HV-RFC and the ESR of the filter capacitors -- 
assuming that the alleged anode/grid arc actually took place.  

>The paper goes on to explain why the 3-500Z and 8877 grids and
>cathodes must be limited to a < 4 Joule fault. If you cannot get the paper,
>I will copy it and send it to you. Call Reid for it first; I know you will
>not be happy until the author is revealed.
>
Thanks, however, If the paper is unsigned, receiving a copy of it would 
not reveal the author.  OTOH, Mr. Brandon quite probably reads the [AMPS] 
mailing-list, so perhaps he can enlighten us.  
cheers
Rich...

R. L. Measures, 805-386-3734, AG6K   


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