开云体育

Mac,

While I agree with you that the original Tek construction note doesn't show a connection for the BNC shell, it seems clear to me that while "normal" practice would be to ground the shell of the BNC, Tek might have had a good reason to ensure that the "Meter LO" terminal and the BNC shell were connected. The "LO" terminal is connected to ground in all switch positions except 2 and 5. These are only in operation when Beta of the pass transistors in the mainframe is being checked. It is my contention that Jared is correct in connecting BNC shell to the "LO" terminal and not to ground; after all, on pages 6 & 7 of his updated document, he does point out that the oscilloscope should be disconnected to prevent erroneous readings when checking Beta of the mainframe pass transistors, as it is in positions 2 and 5 of the switch.

I have to admit that I find the switching arrangements mind-boggling and that others with better observation, reasoning and knowledge might disagree with my contention. Of course, when Tek originated this tester, there were no cheap transistor checkers available and so simply bringing the terminals of the pass transistors out to front-panel connectors wasn't an option, but it could be these days. I have "bodged" such an arrangement in the past and have an idea to do a more permanent arrangement with another junk plug-in sometime in the future.

Colin.