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[AMPS] parasitics

To: <amps@contesting.com>
Subject: [AMPS] parasitics
From: measures@vc.net (Rich Measures)
Date: Wed, 6 May 98 07:40:22 -0800
>>>Ok Carl, I have asked SEVERAL other times for theories for YOUR view of 
>>>things, but haven't gotten any. 
>>
>>Like what?  I'm not the EE who keeps asking questions but never supplies
>>any answers of his own.  I've explained my beliefs on parasitics, switch
>>arcing and gas arcs enough times. I see no need to keep repeating myself.
>>
>
>Uh..no you haven't.  I have asked you several time to explain the Rocky 
>Point effect or Gas Discharge theory for tubes.  

During the grate vhf parasitic debate, Mr. Rauch tried to blame parasitic 
damage on gas discharge.   I asked him to explain why tubes with bent 
filament helices (fil./grid short)  typically exhibit normal vacuums 
prior to autopsy.  Mr. Rauch claimed that the gas disappears between the 
time the arc occurred and the time the tube is subsequently tested for 
gas with a high-pot. tester.  

> I have made several 
>requests for this.  I am curious as to why the filaments get bent.  

I was curious why the cables on large arc-welders jump around when the 
arc is being struck.  I found out that it's due to electromotive force.  
Move electrons in a conductor, and you get. force.   .  .  In 3-500Z 
amplifiers, there have been reports hearing a big-bang.  Subsequently it 
is found that one or both of the 1a grid RFCs are open because the copper 
wire melted, and that one or both tubes exhibits a fil./grid short when 
the filaments are lit.  A photograph of such appears on page 15 in the 
September, 1990 issue of *QST* article "Parasitics Revisited". .  

>Not that I really care since I don't own any 3-500Z's but I am just curious.  
>So, please help me to understand the other theories that exist in 
>addition to the parasitic theory of Rich's.  And saying that a gas arc is 
>what causes the problem is not explaining the theory.  If a tube is 
>evacuated, how does a gas arc occur?  See, I am not an expert on tubes 
>and I am asking for some help here.  Perhaps you've explained all this 
>before.  OK.  Call me dense.  Explain one more time.  If necessary a 
>private e-mail would be fine.  You seem to think that I have bought the 
>parasitic theory hook line & sinker.  I haven't.  Just don't know what 
>the other theories say.
>
>>> I am perfectly willing to listen to what 
>>>you say on these.  How can I make up my mind on anything w/o hearing all 
sides?
>>>
>>>Just one thing Carl, Rich told me that in the 3-500Z's that he has 
>>>analyzed, he hasn't seen any carbon scoring marks that would indicate 
>>>an arc.  EVERY and I mean EVERY arc that I have ever seen leaves plenty 
>>>of carbonization around the area where the arc occured.  So, please include 
>>>in your theories how an arc can occur that leaves no carbonization.
>>
>>
>>Dick Erhorn beat me with the answer...I'm amazed you even asked that
>>question.
>
>Well, maybe.   Although I do have a follow up question to ask everyone on 
>this.  And I also don't think I asked the proper question either.  Rich 
>and I spoke on the phone last week and I thought we talked about carbon 
>scoring, 

As I recall, Jon, we talked about arc-scoring/arc-marks, wherein  
cratering is formed by metal that is evaporated into the plasma during an 
arc.   .  


cheers
Rich...

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


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