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

[Will Matney]

Dan,
Do you mean the anode or inside the glass envelope glowed? If you seen 
glowing in the envelope, it was a gassy tube. The anodes are designed to 
run hot. Excessive grid current of some sort is what blows the resistor. 
The causes are from what Richard described earlier. You'll know if the 
anode fins come loose and drop down on the ring, you could see it. The 
only others things are shorts to the grid.

Will Matney


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