[R-390] Tube Tester

[djmerz at 3-cities.com]

Bob,  I would be interested in the circuit of what you propose.  Not that
I would likely end up building it but it would be "educational" to see how
simply it might be done.  There are other classes of tubes/older stuff
that it might be useful for as well,  best regards,  Dan
> Hi
>
> One of the truly amazing things about the current surplus scene is that
> a reasonable military tube tester (say a TV-7) from the 1950's sells
> for almost as much as a reasonable military radio (say a R-390A) from
> the same era. By the time you buy a reasonable set of test gear you
> have invested as much or more than you put into the radio.
>
> So here's the question:
>
> Is there any interest in a "R-390A only" tube tester? As far as i can
> see you could make one with a handful of parts that would test all the
> tubes in the R390A except the rectifiers. It should do as good a job as
> a TV-7 on the R390A tubes. One advantage would be that the number of
> switches involved would be small. The ease of use factor on the simple
> tester would be significant if you check a lot of tubes.
>
> Is anybody interested in a gizmo like this? If there is then it's
> probably worth figuring out how to do it. A lot of us already have tube
> testers so it may not be worth doing.
>
> This would be strictly a "here's the schematic go to it" type of thing.
> I have no intention of trying to sell them or build them. All the
> wiring would be point to point stuff. The parts except for the tube
> sockets would all be Radio Shack type stuff. The tester should be a
> reasonable weekend project with plenty of time taken off necessary
> distractions like *using* radios.
>
> If you are interested let me know. The only thing I need to know is
> weather you already have a voltmeter / current meter. If so what is the
> lowest current range it will show? The gizmo can be designed for a
> "plug in" meter or a built in. The design will be a little different
> depending on which way we go.
>
> Parts list (more or less):
>
> one 9 pin tube socket
> two 7 pin tube sockets
> two 6 volt filament transformers
> one push button
> one dpdt switch
> one 1N4007 diode
> 3 - 6 0.01 uf caps
> some number of resistors
> a power cord, fuse and on/off switch.
> Depending on the voting either a couple of pin jacks or a meter
>
> So any takers?
>
> 	Enjoy!
>
> 		Bob Camp
> 		KB8TQ
>
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