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EL34 tube problem on HICKOK 539B tube tester!!



 
 
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  #1  
Old April 26th 05, 03:08 PM
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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  #2  
Old April 27th 05, 06:28 PM
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
  #3  
Old April 29th 05, 04:20 PM
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!
  #4  
Old April 30th 05, 02:13 AM
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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