|[AMRadio] AMRadio Digest, Vol 121, Issue 15|
Poli, Louis (US SSA)
louis.poli at baesystems.com
Mon Feb 24 12:32:40 EST 2014
All you need do is measure the DC voltage at the pins.
It will regulate it very well, and there are only two pins used in these tubes.
The 0A2 will measure at 150 Vdc, and the 0B2 will measure at 108 Vdc.
I think the orange glow is of the 0B2 type; however if they were designed to use the same gas then they will have the same color.
But no issue, look up both these at Franks' electron tube pages.
It will be Frank dot Pocnet dot net.
All the tubes beginning in zero are this class. There aren't many.
Check the Base diagram of any you look at.
Some are full size octal base types; like the 0D3 and 0C3.
Here is a little bit of trivia.
The 0C3 is slightly radioactive.
To fire a plasma in tubes like this; reliability was greatly enhanced if you put a trace of a radioactive gas in the envelope too. I think it is a radioactive isotope of helium.
The radiation (alpha/beta particles) emitted will constantly keep the other gas slightly ionized; so turn on was quite reliable.
From: amradio-bounces at mailman.qth.net [mailto:amradio-bounces at mailman.qth.net] On Behalf Of amradio-request at mailman.qth.net
Sent: Sunday, February 23, 2014 12:00 PM
To: amradio at mailman.qth.net
Subject: AMRadio Digest, Vol 121, Issue 15
Send AMRadio mailing list submissions to
amradio at mailman.qth.net
To subscribe or unsubscribe via the World Wide Web, visit
or, via email, send a message with subject or body 'help' to
amradio-request at mailman.qth.net
You can reach the person managing the list at
amradio-owner at mailman.qth.net
When replying, please edit your Subject line so it is more specific than "Re: Contents of AMRadio digest..."
1. Tube ID (Jim Wilhite)
2. Re: Tube ID (Rob Atkinson)
3. Re: Tube ID (Larry Szendrei)
4. Re: Tube ID (Rob Atkinson)
Date: Sat, 22 Feb 2014 16:42:28 -0600
From: "Jim Wilhite" <w5jo at brightok.net>
To: "AM Radio Discussion List" <amradio at mailman.qth.net>
Subject: [AMRadio] Tube ID
Message-ID: <2039AD411845495EB68553640EEDFC00 at JimPC>
Content-Type: text/plain; charset="iso-8859-1"
I have a voltage regulator that is not marked except for the following: 816B997. In circuit it glows bright orange.
My memory fails me at the moment, is it an OA2? It is a 7 pin miniature tube.
The OB2 glows a purple color but I forget what color the OA2 glows, or for that matter what this tube may be if not an OA2.
Date: Sun, 23 Feb 2014 07:02:40 -0600
From: Rob Atkinson <ranchorobbo at gmail.com>
To: Jim Wilhite <w5jo at brightok.net>
Cc: AM Radio Discussion List <amradio at mailman.qth.net>
Subject: Re: [AMRadio] Tube ID
<CALWD7Z5hoR_0gj2h3Bzw9sr+5TMaUSN9HbVFkB4REZfgsjpJZQ at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
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?
On Sat, Feb 22, 2014 at 4:42 PM, Jim Wilhite <w5jo at brightok.net> wrote:
> I have a voltage regulator that is not marked except for the following: 816B997. In circuit it glows bright orange.
> My memory fails me at the moment, is it an OA2? It is a 7 pin miniature tube.
> The OB2 glows a purple color but I forget what color the OA2 glows, or for that matter what this tube may be if not an OA2.
More information about the AMRadio mailing list
This page last updated 25 Feb 2018.