Alan--

Ah, I see. But at least I can still get relative readings from tube
to tube, I suppose. (i.e. Get a scale reading for a known good tube,
and compare others to it.) That is of some use to me--if the readings
are somewhat linear.

Oddly, the "Good/Bad" reading seems to work properly for 12AX7's.
(Known good tubes test in the midle of the green range, and a couple
of known weak tubes test just below green or into red.) Can you
comment on that?

Questions:

Do I risk damaging these 9-pin tubes by testing them in the I-177?

Is there a preferred Gm-capable tester for 9-pin tubes?

Thanks,

--E


P.S. I forgot to mention that my attempted Gm readings were done with
the "L" dial set to "Gm" (i.e., 60), as is standard practice.