Jim Haynes wrote:
Maybe we need to discuss what you really want to accomplish.
My experience with T-17 microphones 50 years ago is that they are
just not very sensitive. I assumed this is deliberate - to make
yourself heard over the noise in an airplane you have to yell into
the mike.
Now if you want to preserve an authentic T-17 then I guess something
like baking the transmitter is about your only hope, and you can only
hope to make the mike as good as it was when originally manufactured.
I remember lots of guys in the old days, who were not interested in
historic preservation, simply took the carbon element out of the
T-17 and attached the wires to a Western Electric F-1 element and taped
it in place. F-1 was the element used in the 302 telephones, forerunner
of the later T-1 used in the 500 type sets.
If you want to preserve the appearance of the T-17 but not the
authenticity, then maybe you could get the original element out and
replace it with either a T-1 or an electret mike behind the faceplate
and nobody will know the difference (except you will sound a lot
better on the radio).
I was working with some military handsets a while back that use the
equivalent of a T-1, and replaced the old transmitters with new T-1s.
I also got an electret T-1 replacement from Mike Sandman - it was
designed for use with a modular-corded handset, but with a little
hacking I got it to fit into the older kind of handset.
Has anyone worked out the circuit to use an electret like you get from
Radio Shack - they have 2 and 3 terminal models - to replace a carbon
element?
Jim W6JVE
Jim, I'm surprised you didn't need an amplifier with that electret
element? That's what the carbon-compatible mics use in 2-way and
avionic installations to get the required output level and the correct
low-Z. Also, the larger telephone elements won't fit inside the T-17
housing and would have to be mounted, up front, as you mentioned. I did
a military mic article for the June 2007 issue of Electric Radio, if
anyone's interested. DE K3HVG
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