Converting a M-80C/U Military Mic for CB use ?

[WK2]

Do you guys think it would be a good idea to convert a M-80C/U Military Hand Mic over for CB use on my Galaxy ? It's brand new in the box. I have already converted a LS 454/U Loud Speaker for use and wanted to keep the Military theme going.

M-80/U Specs : made by Sonetronics - Dynamic noise cancelling push to talk. 150 ohm impedance. 300 - 3500 Hz frequency response with 5 Pin connector.
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Thank You in advance

[MDYoungblood]

Don't see why not, it has a 5 wire cord, two wires are the mic element and the other three are the PTT, shouldn't be hard to figure out with a ohm meter.

3's

Greg

[Bluerunner]

Some of the older military microphones used carbon elements, and so they didn't produce any output voltage on their own. A small current had to be run through them which changed as the resistance of the carbon mic changed with the voice.

Hook up your DMM on millivolts AC to the mic element wires and talk into it. If it produces a fluctuating voltage then you might be able to use it in a modern CB. Might sound good, might not.

If you don't get any AC millivolts out of it then put the DMM in 200 ohms mode and talk into it. Should get a fluctuating resistance with voice if it is the carbon type.

I had an old CB that used a carbon microphone. The carbon mic element was in series with the power feed to the final and simply modulated the power feed to produce AM modulation.

Just FYI: In WW2 the Japanese used a "condenser" microphone made out of two layers of foil that sandwiched some bees wax. The condenser microphone was part of the oscillator circuit which was FM modulated by the varying capacitance caused by the voice. Had problems with them in hot weather and the wax melted. Good example of using limited resources in hard times to achieve an objective though.

[Lost Ram]

I learned something new today, thank you!

[WK2]

I checked the TM's (Tech Manuals) today and got the pin out for the mic. The M-80C/U had a production date of 2003 on the box so it is a Dynamic Mic (electromagnetic induction) and not the older carbon type. Just for grins and giggles I will break out the Fluke Meter and see what it reads and report my findings. Thank You everybody with the help so far and when everything is ready to go I will let y'all know

[MDYoungblood]

If there is too much noise canceling the mouth piece unscrews and you can remove a couple lays of material. I read the spec's, hope I don't get a visit from the DOD.

3's

Greg

[WK2]

If there is too much noise canceling the mouth piece unscrews and you can remove a couple lays of material. I read the spec's, hope I don't get a visit from the DOD.

3's

Greg

Thank You MDY and I don't think any G-Men will show up on your doorstep.

I set my Fluke to V-AC and tested out the element and came up with 0.001 V-AC resting and 0.013 V-AC when I spoke into it. I take that as a good test. Now I just need to test out my old RK-56 and see what it is producing.

After spending much time surfing CBRT this past holiday weekend my interest has been peaked with the Yeticom Optima MK3. I might just hold off on doing the 4 pin swap out and might do a 8 pin swap out instead. I need space in the H3 and if I get the Optima I can mount it in the dash below a different head unit for regular AM/FM/MP3 stereo and free up space on the dash and not advertise what CB I have in my ride. So back to the drawing board.

-- Saturday, 20 June 2015, 22:25 PM --

I know it's been awhile since I last updated this thread but here goes.

I finally got off my backside and went down to Rat Shack and picked up a 4 pin connector. I soldered everything up and have tested it out on multiple occasions with great reports back that I was sounding loud and proud. I would switch between my old RK-56 and the M-80C/U and no one could tell the difference between the two. I am very happy with the results and if anybody else would like to try one out the Pin Out will be posted below.

Pin Out as follows :

Pin 1 - Black Wire plus Shielding Braid (Shielding Braid will be wrapped around the Red Wire)
Pin 2 - Red Wire (Audio Lead / MIC)
Pin 3 - Green Wire (Transmit Control / PTT)
Pin 4 - Not Used

Take It Easy out there in CB Land