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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"K3HVG" wrote in message
...
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


Since T-1 elements are fairly plentiful one can get the
carbon granules out of one to repack the T-17. I did this a
long time ago to repack a Western Electric 375 double-button
broadcast mic. It worked fine but was, of course, tedious.
Where the original carbon granules have been fused due
to excessive current (too much voltage) simply drying them
out will not fix them, they must be replaced. I don't
remember how the T-17 element is constructed but most carbon
mics are made so that replacing the carbon can be done.


--

--
Richard Knoppow
Los Angeles
WB6KBL

When I used to use them, we always repaired them by several sharp bangs
against against anything sturdy enough not to be damaged by the "hammer".

W4ZCB

On Feb 2, 6:48*pm, "Richard Knoppow" wrote:
"K3HVG" wrote in message

...



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

* * Since T-1 elements are fairly plentiful one can get the
carbon granules out of one to repack the T-17. I did this a
long time ago to repack a Western Electric 375 double-button
broadcast mic. It worked fine but was, of course, tedious.
* * Where the original carbon granules have been fused due
to excessive current (too much voltage) simply drying them
out will not fix them, they must be replaced. I don't
remember how the T-17 element is constructed but most carbon
mics are made so that replacing the carbon can be done.

--

--
Richard Knoppow
Los Angeles
WB6KBL
- Hide quoted text -

- Show quoted text -

Yeah; doesn't 12 volts sound a bit high? While approx 100 ohms plus
1200 phms = 1300 ohms and therefore 12/13000 = about 9 mlliamps
current, just wondering if a combination of packing, moisture and
maybe a bit of carbon granule sparking at too high an energising
voltage could be contributing to the problem?
Energising voltage of around 3 volts was typical in many dry cell
telephones sets; or even on sets where 48 volts is/was fed out from
the telephone Central office .