I-177 have too much voltage for later tubes?

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I-177 have too much voltage for later tubes?

Postby Col. Colt » Mon Feb 29, 2016 9:22 am

I keep hearing that, even with the MX-949 Adapter box, which has sockets for more modern tubes, you should not use the I-177 for testing these modern tubes. True or False? Is there a particular base size not to test, even if it fits? Could you feed the tube voltage from another source?

It seems odd that the US Military would produce an adapter that would compromise results....

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Re: I-177 have too much voltage for later tubes?

Postby Admin19 » Mon Feb 06, 2017 7:17 pm

Along with the MX-949 box, you need the later version manual inside, and you will find in there the settings for the MX-949, for all later tubes. It works fine. For extremely high gain tubes, grid signal may be a bit too high, but it has settings for 12AX7, and even that works fine with my I-177. Moreover, people don't notice, but I-177 can also read Gm directly, you need to set the bias pot in the "Gm" position. It's a great tester.
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