Sudden flash in EL84

[hesamadman]

On power up, one of my EL84's flashes real bright and then goes back to its normal glow. It does it with only the power turned on. Not flipping the standby so no B+ is on the tube at this point. The amp works fine......with the exception of the low E sounding odd to me. Like cutting out but I think thats a whole other issue all together. Could this just be a bad tube?

[sluckey]

On power up, one of my EL84's flashes real bright and then goes back to its normal glow. It does it with only the power turned on.

That's just the filament. I've seen some tubes do it and others not. I think it just means that when the filament is cold, it has a considerably lower resistance than the other EL84. This is easy to prove. While the tubes are cold pull them out and just measure the resistance of the filament for both tubes. I bet the flasher has a lower cold resistance.

I wouldn't worry about it. The flasher may only live for 25 years rather than 50 years. Should affect the performance of the tube otherwise.

[hesamadman]

On power up, one of my EL84's flashes real bright and then goes back to its normal glow. It does it with only the power turned on.

That's just the filament. I've seen some tubes do it and others not. I think it just means that when the filament is cold, it has a considerably lower resistance than the other EL84. This is easy to prove. While the tubes are cold pull them out and just measure the resistance of the filament for both tubes. I bet the flasher has a lower cold resistance.

I wouldn't worry about it. The flasher may only live for 25 years rather than 50 years. Should affect the performance of the tube otherwise.

You're the man!

[sluckey]

My last sentence should read...

    Should NOT affect the performance of the tube otherwise.

Sorry 'bout that.