[Milsurplus] Aw Heck (Was: SIMPLE Carbon Microphone Sub)

[Dave Jackson]

Dave:

I checked one of my T-17 mics. It reads about 6 or 8K until I connect it to
a circuit. 

With 32 ma flowing (23 VDC with a 400 ohms series resistor), the voltage
drop across the T-17 is about 10 volts (appx 310 ohms).  Not quite the 62 ma
the ARC-5 manual says but significantly higher than the 1 ma or so if it was
8K. For a short time it reads in the 300 ohm vicinity until I tap at which
point it goes back to the 6 to 8K range.

Must be the carbon granules are clumping together when a significant enough
current is flowing and un-clumping when there isn't.

I understand about the "senior moments."  I have them all the time.  At
least you figured out what was going on with the pseudo T-17!  That is a
good suggestion about the N-1 element though.  At least you have the
illusion that the setup is original.

73,

Dave WA4OBJ