[Milsurplus] N-1 Carbon Mic Element and T-17s

[Clare Owens]

OK, I see the problem now.  The T-17 I chose to repair has the nicest outer
shell, black plastic as it turns out, and was made by Shure.  It uses a mic
capsule even smaller than the N-1 "modern" mic and the capsule is fastened
to the removable front of the mic.  I finally figured out that either I or
Dave or the other guy who replied back in October was crazy so I just
opened up another T-17 and now it all is clear to me!  The interior of the
second T-17 is completely different, with the removable front being quite
thin and the mic capsule firmly enclosed in the main part of the unit.
Except now the part about how to remove the mic capsule from the metal T-17
is not clear at all.  It seems to be glued/screwed/
somethingorothered in place.   I guess a this point I have nothing to lose
and will just pry it out.

I think I'll probably use my Dremel tool to enlarge the recess in the Shure
mic cover so I can place the N-1 close to the front grille, which already
has a piece of fine cloth in place.

I guess the military just spec'd performance and outer dimensions, not how
to do the innards???

Clare

On Fri, Feb 1, 2013 at 11:31 AM, Jim Haynes <jhhaynes at earthlink.net> wrote:

> It's my belief, unsupported by any evidence, that the T-17 microphones
> were intentionally very non-sensitive so that the user would shout into
> them over the ambient noise in the airplane.
>
> There is a paper out covering the official Western Electric method for
> rejuvenating carbon transmitter elements.  I've attached it, but in case
> the attachment doesn't survive the mail system, here's what it says.
>
> Connect a 6.3V transformer output to the element in series with a 500 ohm
> 1 watt resistor.  Holding the element vertical, rotate it through 120
> degrees in both directions for one minute while the current is applied.
> Do not hit or tap the element and do not allow it to overheat.
>
> While the AC current is on, blast the microphone diaphragm with acoustic
> white noise for a minute or two.  The person who submitted this suggests
> noise from a handheld transceiver speaker held against the element; but
> you can think of other things.
>
> Procedure may be repeated 2-3 times if necessary.
>
>
>
>
> jhhaynes at earthlink dot net
>
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