[AMPS] L-4B grid ckt shorts

[Rich Measures]

>Rich Measures wrote:
>>>
>>P=I^2*R.  P=10a^2*1 ohms =100*1 =100W  Is this the rating of the resistor 
>>in question, Ian?  
>
>I beg your pardon: 

Everybody makes misteaks.  Begging seems a bit inappropriate in such 
company, Ian..  

>...make that 3-and-a-bit amps continuously, for a 1-ohm,
>10W resistor. Therefore whatever current burned that resistor out was
>>3A for several minutes probably, or >>3A for a much shorter time.
>
>The same conclusion still applies, though. It seems incredible that so
>much grid current could be flowing in an oscillation condition. 

Agreed, Ian.  I found it incredulous when I discovered that grid RF 
chokes, which were wound with a gauge of copper wire that had a fusing 
rating of c.15A, could be melted open.  Since such current surges were 
taking place in tubes with excellent vacuums, and since Rs in the VHF 
suppressors was apparently being simultaneously damaged, I (rightly or 
wrongly) concluded that VHF energy was somehow involved.  

I also found it incredulous the first time I looked through a microscope 
at the insides of a gold-sputtered 8877.   What Mr. W. B. Foote said 
would be there, was.  I find it not incredulous that the naysayers avoid 
this subject like Bill and Hillary avoid the subject of Gennifer Flowers. 
 

>  I mean,
>if that was the grid current, how big would the cathode current have to
>be... and where would it come from?
>
The cathode current pulse would be at least as large as the grid current 
pulse.
I have heard of plenty of 10w zeners in the cathode lead shorting during 
such an event.
cheers
Rich---

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


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