[Milsurplus] SIMPLE Carbon Microphone Substitute.

[hwhall at compuserve.com]

 >One nice thing about saying something that seems 
>outrageous:  You know for sure that *somebody* is
>actually reading what you take the trouble to write
 

 I'm always reading what you write. If not immediately useful, it's usually educational.

>The sweet-sounding T-17 is in original condition with
>still-sealed screws and original cord.

I wonder if we wouldn't find something unexpected inside if we peeked in there?? Like it isn't really just a carbon button & switch, but perhaps a tiny transformer, too? Found something like that one time in a couple of mikes that I thought were simple dynamics. If it's just a plain button, then maybe we'd learn something about whose products to look for!

Wayne
WB4OGM


-----Original Message-----
From: David Stinson <arc5 at ix.netcom.com>
To: milsurplus <milsurplus at mailman.qth.net>
Sent: Sun, May 29, 2016 4:23 am
Subject: Re: [Milsurplus] SIMPLE Carbon Microphone Substitute.

Guys, I understand and of course, your points are well-taken.
One nice thing about saying something that seems 
outrageous:  You know for sure that *somebody* is
actually reading what you take the trouble to write ;-D.
At least on the milsurplus list.

I have several carbon microphones.  I have one unmolested
T-17 that gets excellent audio reports and provides 
full modulation on both the BC-669 and the SCR-274N.
I've metered the element repeatedly.  
It reads in excess of 20K every time.
I don't get it, either.

Several other elements I've tried on the 669 measure low 
values (under 200 Ohms) and none of them will modulate
the rig beyond about 20%.  And they sound bad.
I decided to make the carbon element subber so I could
use a "candle stick" mic I have that, no matter what I did
including installing a NOS element, pounding it, heating it,
praying etc. would not fully modulate any of my rigs and 
sounded like doggie doo anyway.  The candle-stick 
mic will look awesome with the rig if I ever do another
display somewhere.
The sweet-sounding T-17 is in original condition with
still-sealed screws and original cord.  
IIRC it's a 1943 contract and is the usual "three-holer."  

I can't explain it. I just report it. 
I wish someone would explain it to me.

73 DE Dave AB5S

P.S. I did try the little subber with bypassed emitter bias
and the large base-to-ground resistor you'd expect.
It resulted in about half the output and no change in
audio quality.  Again- I don't explain it, just report it.
Can someone suggest a transistor with more gain
than the 2N3569 in this application?




______________________________________________________________
Milsurplus mailing list
Home: http://mailman.qth.net/mailman/listinfo/milsurplus
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Milsurplus at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/milsurplus/attachments/20160529/ff16ff7d/attachment-0001.html>