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[Amps] Dimished Tube Life

To: amps@contesting.com
Subject: [Amps] Dimished Tube Life
From: Paul Decker <kg7hf@comcast.net>
Date: Fri, 25 Sep 2009 11:05:38 +0000 (UTC)
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Hi Group, 



I've watched a few of these questions go by over the years, and it made me 
wonder. 



When is a tube considered at it's end of life?   Of course a tube like I posted 
about last week, where there is a grid - cathode short, is (at least right now) 
at its end of life.   But if over time the tube is simply having reduced output 
or "going soft", at what point is it considered "no good"; at 95%, 80% 75% 
output?     



 I'm sure there is a technical answer, but there is also a real world answer, 
as an example, I would be perfectly happy if someone sent me a "soft" 3-500z  
;)    It would not bother me in the least if it was only capable of producing 
75% output, I'd probably be perfectly happy with  tube that produced 50% output 
as it's better than the 0 I have now.  



I was an RM on subs, we ran our urt-23/am3924 PA's which use a pair of 
4cx1500B's 24/7 for over 80 days at a time.   The only time we them down was to 
do any preventative maintenance and when we transferred our guard to the shore 
com stations.    On the other hand, we rarely ever transmitted, so they just 
sat in standby.  In fact, on the boat I was on, there were probably more hours 
logged transmitting on the amateur bands than on the military nets.   If any of 
you have a contact from me between 1986 and 1992, likely it was from the boat.  



73, 
Paul (KG7HF) 

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