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Hickok I-177 tube tester

The Hickok I-177 is a tube tester from WW-II. This model was made for the US armed forces. It is robust and durable and is available in three colors: Navy blue, grey and olive drab. It is capable of testing US tubes that were used by the armed forces in WW-II. Using an extension box, also newer types can be tested. I bought this one because of its robustness, and because it is extensible. I hope this will help me to test valves I cannot test with the B&K model 700 I bought earlier. That is, once I have restored it.

Tube testers have always fascinated me. Although it is easy to set up a simple test circuit to verify that the valves you have are still working to their intended specifications, it takes quite a lot of tinkering if you want to carry out more tests on a valve or if you need to test different types. A test circuit for every test. It is much more convenient to have a single box that contains test circuits for all conceivable tests for all types of valves you think you want to test. Now it is possible to build a tube tester yourself, but you will have to calculate the right operating conditions and expected readings from the data sheets for every type of valve you want to test. For a radio serviceman (including those in the Armed Services) it will save a lot of time if the settings of such a box are easily made, and if a booklet comes with it that states the settings and acceptable readings for all types. By doing so, he can rely on the knowledge of the manufacturer of the tube tester.

    Olive drab case.

Olive drab case.

    Label of the US Army Signal Corps.

Label of the US Army Signal Corps.

The Hickok I-177 is an American tube tester from WW-II. This model has specifically been built for the US armed forces. My specimen has a label “US Army Signal Corps” and the case is painted olive drab. It is a robust tester, offering gm (mutual conductance) and emission tests. It has a limitation though: originally it can only test US tubes from WW-II. Newer types can be tested using an extension box, the MX-949 A/U Adapter that contains 7 and 9-pin miniature sockets. I don't have such an adapter, but it is easy to construct one.

This tube tester contains two rectifiers to supply the testing voltages:

The reason why I bought this type of tester was that I needed to test the rectifiers in my B&K 700 tester. And I wanted a tester that I could be easily adapted to test valves that I have data for, but which are not in the tables. The B&K 700 tester is not easily used for that.

Closer look at I-177

A closer look at the controls and sockets of the I-177.

I bought this tester through an Internet auction site in January 2009. The price was right, but I had to accept that the case was quite rusted. When I collected it, the smell made clear that it had been stored in quite damp conditions. But I will try and make it work again...

Copyright © 2009 by Onno's E-page         published 2009-03-08