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maxxtro
 
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Default EL34 tube problem on HICKOK 539B tube tester!!

Hi:
I have one Mullard EL34 tube. I test it on my HICKOK 539B tester. I
turn the tester power on after 1-2 minutes the micromhos meter is read
on 5600. But test after power on approximately 6-7 minutes the
micromhos meter indicator is reverse and turn the BIAS VOLTS VR is no
function. I test other EL34 tubes have no any problem on the 539B
tester. Does the Mullard el34 or the tester have any problem ?
Please help me to close the problem.
Thanks and Regards!!
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Alan Douglas
 
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Hi,

I have one Mullard EL34 tube. I test it on my HICKOK 539B tester. I
turn the tester power on after 1-2 minutes the micromhos meter is read
on 5600. But test after power on approximately 6-7 minutes the
micromhos meter indicator is reverse and turn the BIAS VOLTS VR is no
function. I test other EL34 tubes have no any problem on the 539B
tester. Does the Mullard el34 or the tester have any problem ?


Sounds as if your EL34 has grid emission, and it takes a few
minutes for the grid to heat up. It is contaminated with material
from the cathode.

Alan
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maxxtro
 
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Alan Douglas adouglasatgis.net wrote in message . ..

Sounds as if your EL34 has grid emission, and it takes a few
minutes for the grid to heat up. It is contaminated with material
from the cathode.

Alan


Hi:
The means the Mullard el34 tube is bad can not work on the Amp?
Thanks!
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Alan Douglas
 
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Hi,

Sounds as if your EL34 has grid emission, and it takes a few
minutes for the grid to heat up. It is contaminated with material
from the cathode.


The means the Mullard el34 tube is bad can not work on the Amp?


Yes. If the tube has grid emission, it will work for a few minutes
but then the plate will glow red, as the grid bias goes positive and
the tube draws too much plate current.

Alan
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