NRI Triplett tube tester
 

Saw a tube tester locally on CL. It's a national radio institute 1185 which I believe were made by triplett in the 40's? So how old is too old for a tester? Wouldn't mind having one but never heard of this model.

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Decided to take a chance and pick it up. Not too many caps or resistors. Should be quick replacements. Came with a bunch of tubes. I have the schematic but no user manual.


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First off, to my knowledge N.R.I. was a correspondence type of school and much of what I have seen or owned was made at home by students with the parts provided by the school. It may still exist in some form, but it seems to me that the name changed somewhere along the way as a "radio" school wouldn't draw a big student body.

A number of years ago I acquired a deceased repairman's entire compilation of books and two pieces of his home built equipment. All I knew was that I had a power supply chassis and another with a c.r.t maybe 3" diameter. I guess it was an oscilloscope. All I know is I placed an ad (maybe here) for the stuff and some big time collector sent me a check for $900 sight unseen (not even a picture). With that being said, you may want to put it in the classifieds!

As far as practical use, I don't know what you work on, but you can look at the sockets and see your limitations. It would probably be find if you are doing early radio only. It certainly looks nice and well built having more of a manufactured look than what I had which was very bare bones to say the least.

I paid $80 for it and figured I was sticking my neck out given the age and number of sockets. So far I have only worked on old radios so I should be fine there unless I start to branch out. I don't see one like it on eBay so I guess there aren't a lot of them. It has only one .1 mfd cap

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I think that you did great given the condition, all the documentation that I see, and the probable rarity. As far as $80 goes, I was just reading somewhere else how tube testers are increasing in value while other older test equipment remains pretty cheap like VTVMs. I made the mistake of paying about that for an old Heathkit C3 capacitor tester that "worked." Turns out all of the bridge is off, so I can't get a value, then I find out that my DC voltages are all very low, so it's probably a rebuild on something that I wanted to help me in troubleshooting.

I got hasty in my buying, so its my fault I guess. I thought that getting it through this site would give me a better shot at something actually known to be working by someone who knows what to look for as opposed to some ebay flip.

Oh, it's also great if all you have to deal with in capacitors is a .1mfd! I seem to keep bunches of those. I want also to say that I believe this unit to be a simple emissions tester with no bells and whistles like mutual conductance and such. Still in all, it will serve you fine with radio applications and some others.

Does this look like a .1 to you? Just making sure. If it is it doesn't matter that it's polarized.


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Sweat the dirty wax off with some heat, maybe that will clarify things? I can't tell if there's a dent in it or if maybe that's a decimal point.

its a .1

Yeah. I found it in the schematic. Can't believe I missed that. I've never seen a 1 mfd but I imagine there's one out there somewhere.

Anyway, replaced the cap and the cord and this thing actually seems to work. Tested it on an untested original 26 rectifier and got 86%. I need to verify the results with aknown tester. The spec cards contained the operating instructions which helped big time. Need to make good copies of those.

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Many paper caps had that 'outside foil' / '- polarity' mark despite being non-polarized...The reason for it was so that end could be connected to the chassis and the 'outside foil' would shield the cap from picking up any noise from the surrounding circuits etc. in sensitive radio applications.