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

[hwhall at compuserve.com]

 >
That is a good suggestion about the N-1 element though.  At least you have the
illusion that the setup is original.
>

 
An N-1 is what I used to put the aviation museum's T-17 back to working for the Link Trainer working-display. I still want more sensitivity & haven't had time to go looking for it yet. I may have some issue in the audio circuitry & not just the mike.

Wayne
WB4OGM

 

-----Original Message-----
From: Dave Jackson <cjack93907 at razzolink.com>
To: 'David Stinson' <arc5 at ix.netcom.com>; milsurplus <milsurplus at mailman.qth.net>
Sent: Sun, May 29, 2016 8:29 pm
Subject: Re: [Milsurplus] Aw Heck  (Was: SIMPLE Carbon Microphone Sub)

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




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