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24.140.236.241
I have 2 monoblock amps and each uses one 0A2 tube to provide ~150 volts to the plate of the input/driver tube. One is working fine, but the other measured 165 volts. When i put another 0A2 in its place I got the voltage I wanted. Is the one providing 165 volts defective? To the best of my knowledge it is new and never used. I really don't understand how these things work so any answer would only add to my limited understanding. TIA
Follow Ups:
The tubes are filled with different Noble Gases depd on the voltage desired.
It usually Argon, Neon, etc. The voltage desired can be set by fill pressure, or, using mixtures
of gases. Remember the ionization energy series of atoms you probably learned in college chemistry - its all that!
-- Jim
Great, exactly what I need! Thanks!
The 90V 0B3 is a very pretty indigo...though it is usually pretty hidden by the gettering...
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
You can get all kinds of voltages if the tube isn't actually on - is it glowing visibly?
Well yes it does, but I would have thought that subbing another tube and getting the correct voltage implied that to be the case.
No, it's not defective. The RCA tube manual states the 0A2 anode voltage drop can range from 140 volts to 168 volts.
It's just normal variation from tube to tube. Also, the tube can take 20 minutes or so to stabilize at its normal voltage. And over the life of the tube that voltage may drop some.
Whenever you are checking out a component like that you need to pay careful attention to the operating conditions and tolerances.
http://www.ez260.com/rca-0a2-datasheet/
I would suggest the tube is faulty.
Regulation of this stabilizing tube should be typically within 2V and max 6V from 150V reference, as per the datasheet.
"Regulation of this stabilizing tube should be typically within 2V and max 6V from 150V reference"
The number "150" doesn't even appear in that datasheet. It clearly denotes the minimum tube value as 140V and maximum as 168V. 6V is the maximum variation resulting from changes in tube current, with 2V being typical.
--------------------------
Buy Chinese. Bury freedom.
You are correct, my error.
I can say that having tested 40x VR tubes in the same circuit that they all measured within 1 Volt of nominal value - so my interpretation was based on personal bias.
Having looked at additional data sheets only confirms that your point is correct.
Shane
Thanks, I was looking at 0A2WA data sheet not thinking there would be any differences. Should have referred to RCA 0A2 data sheet since that was what I was using.
The 0A2 and 0A2WA have similar tolerances.
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