[Amps] tube glowed red when grid resister blew on sb-220

[R.Measures]

Dan --- When a 3-500Z's grid fusing resistor blows, either the tube is 
loosing it's vacuum, the anode cooler spot-welds have broken (allowing 
loose anode to contact grid), or there has been an intermittent  VHF 
oscillation which produced a surge in grid-I.   A purple/blue glow 
suggests that there's air inside the tube.  cheerz

On Sep 12, 2004, at 7:44 PM, Dan Sawyer wrote:

> All,
>
> Recently one of grid resisters blew on an SB-220. The result was the 
> tube glowed deep red to purple. Is this a reasonable outcome for a 
> blown grid resistor on an SB-220? If the incident was only a few 
> seconds long was the tube damaged??
>
> Thanks,
> Dan
>
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Richard L. Measures, AG6K, 805.386.3734.  www.somis.org