[AMRadio] Tube ID

Jim Wilhite w5jo at brightok.net
Sun Feb 23 12:06:19 EST 2014

Thank you Larry, Rob and Kim,

I read about some examples on the net that Kim found but they all were the 
octal base.  I also found a data log but they did not have a spec sheet or 
picture on the OC2.

The deal is the tube was in the regulator circuit in an NC 183D that I 
bought last week.  The specs for the receiver calls for the OB2 which is a 
105 V regulator.  In all my years I have never run across the OC2 in the 
miniature envelope which is the one you mention.  I am not sure if someone 
before me wanted to run the regulated voltage at 75 or they didn't have an 
OB2 so they just installed the OC2.

In any case thanks for the information guys.  I recall reading an article 
about the color of the regulator tubes and which type of gas causes the 
color but could not find it.  There is a lot of that type of information on 
guitar and audio sites but they don't have the spec sheets posted.



-----Original Message----- 

The OC2 is a 7-pin miniature that glows bright orange; it's a 75-volt

If you have access to a TEk 575 or similar curve tracer it's very easy
to measure, also it's almost as easy with a bench supply, current
limiting/voltage dropping resistor, and a voltmeter.


On 2/23/14 8:02 AM, Rob Atkinson wrote:
> Hi Jim,
> I think I'd measure the voltage at that tube's socket and stick a
> known VR tube in there for that voltage and see what happens.  But, my
> knowledge is somewhat limited.  I guess a VR tube with neon in it
> would glow orange.   5651 and 5651A are miniature neon VR tubes I
> think.  90C1 or 85A2?
> 73
> Rob
> K5UJ

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