The Heathkit IT-121 FET/Transistor Tester

In this video we'll look at a piece of vintage test equipment, the
Heathkit IT-121 FET/Transistor tester. I'll give a little background on what transistors testers are, the devices they can test and the parameters they can measure. We'll cover the specific features of this instrument, and look at the front panel controls and inside circuitry. I'll discuss the restoration of this particular unit, and say something about the circuitry it used. We'll see a demonstration of the tester in operation, and then wrap things up with a summary.

[@darwinbyal6021]

I built one of these testers in the early 70s. My family had purchased a Sylvania color TV which was one of the first to be completely solid state. As mentioned in the video, early transistors were socketed and subject to failure. I'm no electronics genius but I am proud to say that I was able to fix all the failures in that TV over the years that we owned it.

[@JohnUsp]

Thank you for your video. I bought a B&K Precision Model 162 Transistor and FET Test and your video taught me how to test it. My 2N2222 achieved 250 Beta ;) I guess the datasheet says Collector, Base, and Emitter from left to right on the flat side.

[@uni-byte]

I built one of these back in in the late 70's for my workplace. Cool.

[@ys1rs]

Excellent as always!
I bought one IT-121 from eBay just for the learning sake of it and have the experience of using such a piece of equipment apart from being a collectors item.
Compared to other Heathkit test equipment this one looks complex to use but is just the fact that it can measure FETs, transistors, diodes and more, each having different settings and parameters.
Found a wire wrongly soldered, other than that it was like new. Have not gone through measuring any component yet for a real life scenario apart from checking it and aligning it.
Usually I use a Chinese cheap ESR tester.
Thanks for the video. It confirms what I had done was correct and my unit is working fine.

[@SDsailor7]

Great video!

[@ohmedarick1]

Thank you great video. Well explained. Look forward to watching more of your videos.

[@michaelhiggins7365]

Awesome video are very, very informative. Thank you, de KM2U

[@SDsailor7]

I have the Heathkit IT-18 transistor tester that I am trying to learn how to use.

[@paultopolski6595]

Nice job on the video as always Jeff. If you ever get the chance, I'd like to see the IT-3121 curve tracer in action. Aside from the Tek 575 and 576, the only test equipment manufacturers I am aware of that made curve tracers was Heatkit, B&K and Leader. Of course the Tek units were way out of the price range of Radio/TV shops let alone hobbyist. The others of course were much more realistic.Paul, W1SEX

[@SDsailor7]

Where can one buy the test leads for this model? anyone know?
thank you

[@jefftranter]

They are just leads with banana jack to alligator clip. You can buy suitable connectors and wire them up or buy them premade from sources like Digikey, Amazon, or eBay.

[@SDsailor7]

@@jefftranter Thank you, i will look them up.