Re: sencore mu150 continental

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In Reply to: sencore mu150 continental posted by some young guy on September 15, 2003 at 16:11:29:

That is an excellent tube tester--but quite difficult to restore/repair. The circuit design is unique, a square wave grid signal is used, and the bias on the tube under test is set automatically to achieve one of three predetermined plate current levels. In addition, the tester will test a tube for mutual conductance AND emission. The circuit of the tester is a hybrid with tubes, diodes, and transistors. For some reason, the resistors in almost all samples I have seen drifted badly. With these I pretty much rebuild the entire circuit board. If you don't get it all correct, the tester will appear to calibrate, but not give reliable readings. Calibration is much more difficult than other testers, and a scope is suggested. This is due to the need to accurately adjust the amplitude of the square wave grid signal. So--great tester--but not likely to be "Plug and Play". Excellent condition and lack of use may be bad--as the electrolytics may short on power up, and the unit (ones I've seen) do not have a fuse. This means transformer failure--so I add a fuse when rebuilding one. If you want to power the thing up--figure out a way to limit the current to 1 amp to prevent damage if an electrolytic cap in the power supply is bad. This is more likely to be the case with a unit that sat for years than one that has seen regular use.
So--great tester when properly restored and calibrated. Very suitable for audio tubes and later types. Will NOT test old tube types like a 45 or a 2A3.

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Follow Ups Full Thread

Topic - sencore mu150 continental - some young guy 16:11:29 09/15/03 (2)

Re: sencore mu150 continental - Chris Haedt 09/15/0317:12:15 09/15/03 (1)

Re: sencore mu150 continental - GrayBeard 07:33:22 09/16/03 (0)

Follow Ups

Re: sencore mu150 continental - Chris Haedt 09/15/0317:12:15 09/15/03 (1)

Re: sencore mu150 continental - GrayBeard 07:33:22 09/16/03 (0)

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