{LVL1} Tube and analog guys, eat your hearts out!

[Raj]

I recently was given an op amp.  Okay, big deal.  What makes this one different is that it's 7"x2.5" and comes from the early/mid 50s!  I had commented to a gentleman I know, who is in his 80s and has worked in electronics all his life, that I saw a picture of a really old op amp and found it amazing and quite beautiful, in a utilitarian sort of way.  Well, he surprised me by bringing in an old op amp to show me.  When I asked if I could photograph it, he said no.  Instead, he said I could have it!

It's a Philbrick Researches USA-3 model (GAP/R USA-3).  I looked through the philbrickarchive.org web site to date it, and the best I can guess is that it's almost certainly before 1955, as the trace layout and values of some of the components are different than the earliest photos and product literature for it that they have.  Either that, or this one was contract-made specifically for military applications.  Another difference is that the product literature says that a typical unit uses two 12AX7A tubes, a 6U8, and a 6S4A.  In the note, it says that for critical applications one should replace the 12AX7As with 7025s.  It appears at least one was replaced.  Can any of you tube guys tell me what this means?

I have no idea what the monetary value is (feel free to tell me, if you know!) but I believe it has significant historical value, considering that the first commercially available op amps were released in 1953 and made by the Philbrick company.

The kicker?  1.  It still works, according to the guy who gave it to me.  2.  He worked for the military, and it was used in the design and construction of the control systems for nuclear aircraft.  Not airplanes that carried nuclear weapons, but actual nuclear-powered aircraft!

If any of you know anything more about this, please share!  Pics are attached.

-- Raj

[Ben Hibben]

Sweet!  Bring it Tuesday so we can have a look, please!  :-)

Blenster

[Tim Gillespie]

Cool!  It would be fun to use it as an audio pre-amp or make an audio oscillator or some other noisemaker out of it.  As far as I know audio applications are just about the only place that tubes are still used, and that is because all of their quirks and imperfections sound pleasing.

The value of the components wouldn't be too high.  You could buy replacement tubes for $5-$10 each.  I don't know what the value of the whole unit would be, that depends on whether they are collectible I suppose.

7025 is a low noise drop in replacement for a 12AX7.

[stea...@gmail.com]

They never built any aircraft that were nuclear powered, but they did do all the research needed and determined it was quite possible.  I knew one of the nuclear chemists on the project in Oak Ridge. 

Thanks,

Dan

Sent from my iPhone

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[Jeff Johnson]

My grandfather worked on that.  They had a shirt with dumbo on it to celebrate the attempt.

[Pat McCarthy]

I, however, saw the remains of one of some of the experimental aircraft engines in a hanger in Idaho, at the INEL

 

Patrick McCarthy

 

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[Pat McCarthy]

Dug a wee bit deeper (OK, Wikipedia…)

 

The NB-36H Nuclear Test Aircraft (NTA) was to study shielding requirements for an airborne reactor, to determine whether a nuclear aircraft was feasible. This was the only known airborne reactor experiment by the U.S. with an operational nuclear reactor on board. The NTA flew a total of 47 times testing the reactor over West Texas and Southern New Mexico. The reactor, named the Aircraft Shield Test Reactor (ASTR), was operational but did not power the plane, rather the primary purpose of the flight program was shield testing. Based on the results of the NTA, the X-6 and the entire nuclear aircraft program was abandoned in 1961

 

I did NOT know that they actually ever even got one up in the air…. Cool

 

Patrick McCarthy

 

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