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[AMPS] Filament breakage

To: <amps@contesting.com>
Subject: [AMPS] Filament breakage
From: measures@vc.net (Rich Measures)
Date: Wed, 14 May 97 14:01:52 -0700
...snip...
(Carl:)
>>>... I believe that you, Rich and others already agree that
>>> the instantaneous discharge can add many amps to the equation. 

(Tom Rauch:)
>>No, only a fractional amperage increase. The saturated emission 
>>current of a thoriated tungsten 25 watt filament is three amperes or 
>>less. That current must be integrated over time to cause heat, plus 
>>it is the PEAK current. The effective heating would be the time 
>>integrated value of this RF current. If driven by a sine wave, the 
>>heating would be .707 times 3 amperes, or 2.1 amperes times the 
>>resistance. If the conduction waveshape was the same as a typical RF 
>>PA, the current considered for heating would be less than 1/3 the 
>>peak current, or under one ampere.
>Very wrong again Tom. You are staying completely hung up in "proper" tube
>performance and there you are correct. 
>What you refuse to admit is that an instantaneous discharge is a function
>of the voltage and current and has absolutely no bearing on the design
>parameters of the tube.
Yes indeed, Carl  It seems that expert science is taking a backseat to 
"expert" status.  
...snip...
>>The analysis would prove nothing except the filament got hot. It is 
>>impossible to determine the cause of the heating after the fact.
The post-'big-bang' 811A broken filament fragments I have seen appeared 
to be identical to broken filament fragments in an 811A that was 
accidentally dropped. 
...snip...
>The only gas around this discussion is pure methane flatulence. 
Arcs and methane gas are not a good combination, Carl.  
>73...Carl   KM1H
Rich---

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


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