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Testing tubes in the CTC-5, using a Realistic model 108.
I'm getting suspicious results on the 12AT7 color demods. The tester table says to use a quite low setting (4) on the "D" dial, which means a low reading for a given amount of current; that is, the tester expects a lot out of these tubes. Anyway, both demods read really low unless I increase the setting (I tried this because one of the types that could substitute requires a higher setting). Also, the reading jumps to a peak value when the button is pushed and them fades to lower values (easier to see if the "D" knob is cranked up).
Any ideas? Something wrong with the tester? A mistake in the settings table? I have tested about half the tubes and the 12AT7s are the first ones to behave this way. Found one dead 5U4 rectifier, otherwise the other tubes behave reasonably.
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