[Amps] GS35B Idle Current drifting up

[John Lyles <jtml@losalamos.com>]

I've seen indirect heated planar triodes from Eimac Salt Lake products 
that had similar damage. The spacing in those tubes from grid to cathode 
is very close. Bombardment of the cathode from ions would be one 
suspicion. Overheating the anode might be a source of the 'gas'.
Eventually enough of the active electrodes are burned away that the tube 
has comepletely different characteristics, if it can still withstand HV.
John
K5PRO


> Message: 2
> Date: Sat, 21 Dec 2013 15:44:11 -0500
> From: "Gary Smith" <Gary@ka1j.com>
> To: Amps@contesting.com
>
> Nice clear photos. What would have made that happen? And how to best
> avoid it from happening to... lets say, my amp?
>
> Gary
> KA1J
>
> > I opened and photographed a dead one a while ago. The pictures are
> > here:
> > http://gs35b.com/gs35b/bang.html
> >
> > Would the drift happen if a tiny bit of cathode material
> > evaporated and migrated to the grid?
> >
> > Steve
> > _______________________________________________
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