[Marc Lewis]

+ User FidoNet address: 1:396/45
Hello All.

On 16Jul2008 05:43 Sofa Slug wrote a message to All regarding
OB2 Regulator Tube Question

SS I'm working on an old power supply that uses two 0B2 tubes.
SS Both test good, but one glows with an orange color, and
SS the other blue. I have several other 0B2s - all of those
SS glow blue.

SS Is it unusual for an 0B2 to glow orange? Does that indicate
SS a problem?

The blue/violet colour would suggest to me that tube is not a
0B2. The orange glow is neon gas, I recall is used in the 0B2.
Blue/Violet is argon gas and I believe it ionizes at a lower
voltage than neon. The 0B2 has a nominal 108V drop.

I routinely repaired Leslie Organ Speaker amplifiers; the reverb
amp used a 0B2 which glowed orange. The main power amp used a
0C3 which glowed with the characteristic Blue/Violet colour of
Argon.

Best regards,
Marc
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[Sofa Slug]

I'm working on an old power supply that uses two 0B2 tubes. Both test
good, but one glows with an orange color, and the other blue. I have
several other 0B2s - all of those glow blue.

Is it unusual for an 0B2 to glow orange? Does that indicate a problem?

-Thanks

[RapidRonnie]

On Jul 16, 8:43 pm, Sofa Slug wrote:
I'm working on an old power supply that uses two 0B2 tubes. Both test
good, but one glows with an orange color, and the other blue. I have
several other 0B2s - all of those glow blue.

Is it unusual for an 0B2 to glow orange? Does that indicate a problem?


It may.

I would test the tube with a fixture for voltage drop. Use a HV
supply and an appropriate resistor. See if it is the same as the ones
that glow blue.

The colors gas filled tubes glow are a function of what gas is in
them. Different gases have different voltage drop characteristics.
Since you have one that glows orange either neon or some other gas or
mix of gases is in there as opposed to the others.