litterbox99
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- Jul 30, 2022
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Siemens LGR 7641 tube specs.
A few years ago I purchased a HeNe tube & power supply kit.
It came with a Siemens 7641 tube, un-marked power brick
(3 1/4 x 1 1/4 x 3/4) and three 20k 3W metal oxide ballast resistors.
I powered it with a variable power supply (YH-305D) @ 12 vdc
This set up has worked fine for years.
Last time I powered it up, my bench supply glitched and jumped
to 49 VDC, it took me a second to shut it down. Fired it back up
and nothing. I'm, sure the brick is toast because it draws no
mA anymore and the tube wont lase.
Question 1
What are the voltage and current requirements for this tube ?
Question 2
Can you burn out a HeNe tube by too much voltage or amps ?
It doesn't glow when I hold it up to a plasma globe, but my 7631A's
do. I even tried using the supply that runs my 7631's (1750VDC,
5.0 mA) @ a ballast range of 60k-75k. Still no joy.
Guess I smoked them both ?
A few years ago I purchased a HeNe tube & power supply kit.
It came with a Siemens 7641 tube, un-marked power brick
(3 1/4 x 1 1/4 x 3/4) and three 20k 3W metal oxide ballast resistors.
I powered it with a variable power supply (YH-305D) @ 12 vdc
This set up has worked fine for years.
Last time I powered it up, my bench supply glitched and jumped
to 49 VDC, it took me a second to shut it down. Fired it back up
and nothing. I'm, sure the brick is toast because it draws no
mA anymore and the tube wont lase.
Question 1
What are the voltage and current requirements for this tube ?
Question 2
Can you burn out a HeNe tube by too much voltage or amps ?
It doesn't glow when I hold it up to a plasma globe, but my 7631A's
do. I even tried using the supply that runs my 7631's (1750VDC,
5.0 mA) @ a ballast range of 60k-75k. Still no joy.
Guess I smoked them both ?