Re: Dead 833s? (was:RE: new single 833A VTTC)

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Mddeming-at-aol-dot-com 

In a message dated 12/23/03 4:28:01 PM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:
Just wondering, has anyone killed an 833A in VTTC service yet?  If so, what
was the failure and what was the cause??  I for one am very curious!  Even
more curious as to how far you could push one of these tubes before they
give up.

Hi Steve, All,
In commercial service, the most common problem is the plate and grid seals 
melting which results from airflow failure or from the bias resistors going 
toast and causing runaway plate current.
  IMO how far you can push tubes beyond specs depends on several main factors:
1) How many do you have on hand?
2) Are they new or used? (All tubes have a finite life-span)
3) Who made them? (Chinese knockoffs like the FU-33 should be de-rated ~20%)
4) Who has actually paid for them.  (Tubes that have been scrounged, or 
"liberated" from a company budget or research grant, are often pushed 
harder than those purchased at full retail from the Coiler's own pocket.) ;-))
5) How lucky do you feel today?

Hope this helps in evaluating the many conflicting opinions you will get.

Matt D.