[ForSale-Swap] "burning" in tubes

[Carl]

Some Chinese tubes, especially from RF Parts, have been defective at turn 
on. Those are easy to cull as they blow breakers, one half of the filament 
is open, and a nice gas glow.

If it passes that step just leaving them turned on does nothing useful.

Running them at idle current doesnt help either as the plates dont get hot 
enough to recombine any small amount of gas or burn off any rough edges. For 
that the plates have to show a moderate amount of color such as running at 
moderate output on 75M AM or at half power into a dummy load for around 15 
minutes. Stick to 80 or 40M.

Carl
KM1H


----- Original Message ----- 
From: "RAY FRIESS" <rayfrijr at msn.com>
To: "boatanchors" <boatanchors at mailman.qth.net>; "FORSALE" 
<forsale-swap at mailman.qth.net>; "FLBOATANCHORS" 
<flboatanchors at yahoogroups.com>; "glowbugs" 
<glowbugs at piobaire.mines.uidaho.edu>
Sent: Saturday, November 14, 2009 2:09 PM
Subject: [ForSale-Swap] "burning" in tubes


>
>
>
> A friend of mine says that now that I've put in a new pair of 572B tubes 
> in my FL100B amp, I should let it sit, turned on, for 5 hours.  He says 
> that burns in or breaks in the tubes before I put it in line on the air.
>
>
>
> True or just one of those old ham tales?
>
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