[R-390] Tube Tester

[Bob Camp]

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