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Author Topic: Motorola Microphone wired as Yaesu MH-27A8J for FT-2400, 7400 & 2500  (Read 1561 times)
KR5TX
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Posts: 2




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« on: July 30, 2013, 06:32:53 AM »

I have fallen victim to the evil leaking capacitor issue of the Yaesu MH27A8J microphone which at this point is unknown if it is repairable.

I've seen them advertised for sale on eBay so apparently it can be done - anybody know the pinout and how to connect a Motorola HMN1035C microphone for use with a Yaesu FT 2400, 7400, or 2500? I have the pinout for the MH27A8J but don't about the wires for the Motorola mic.

I know it is going to take an RJ45 8 pin plug; just wondering if anyone has had experience with this and if so, how it worked out and how to wire it up.

THANKS IN ADVANCE
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N3HFS
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Posts: 210




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« Reply #1 on: July 30, 2013, 08:49:39 AM »

from http://forums.radioreference.com/motorola-forum/214562-motorola-mic-pinouts.html:

Quote
White wire > mic lo
Black wire > PTT gnd
Red wire > mic hi
Green wire > PTT

You'll need to tie mic lo and ptt ground in the mic for the single wire ground for the maxtrac.
The blue wire (pin 3) is hook and you'll have to attach it to the button somehow if you want the radio to stay out of monitor.

...and this from http://batboard.batlabs.com/viewtopic.php?f=1&t=2970:

Quote
Sounds like you have an "HMN1035C" or equivalent Maxtrac/GM series microphone. Any made in the last several years are the sealed type, and I haven't found a way to open them without destroying the mic housing. You will not detect the PTT line going to ground, as it's not a simple direct short when you depress the PTT button. It grounds through a transistor circuit, using voltage coming in off the "Mic Hi" lead. Leave it to Motorola to design something complicated when something simple would do the trick!
« Last Edit: July 30, 2013, 08:54:12 AM by N3HFS » Logged
W9GB
Member

Posts: 2616




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« Reply #2 on: July 30, 2013, 05:37:41 PM »

Answer from your duplicate posting at QRZ.COM
http://forums.qrz.com/showthread.php?400144-Motorola-Microphone-wired-as-Yaesu-MH-27A8J-for-FT-2400-7400-amp-2500
Quote from: N3HFS
You will not detect the PTT line going to ground, as it's not a simple direct short when you depress the PTT button. It grounds through a transistor circuit, using voltage coming in off the "Mic Hi" lead. Leave it to Motorola to design something complicated when something simple would do the trick!
Microphone uses Elecret element, so the PTT and mic circuit permits switching of DC voltage to elecret element only during PTT.  Schematic at bottom of this posting.

For Product Questions / Support of Motorola Solutions radio equipment, search BATBOARD / BATLABS.
http://batboard.batlabs.com/viewtopic.php?f=1&t=2970

Motorola Mobility (mobile phone buiness) is now part of Google.

Repeater Builders is also a good Motorola documentation / support web site to answer queries.
http://www.repeater-builder.com/rbtip/mojoindex.html

===
HMN1035C Palm-size microphone (see the HMN3596A microphone below).
HMN3596A Palm-size microphone (full documentation, extracted from the GM300 manual).

Motorola GM-300 Product Page
http://www.repeater-builder.com/motorola/maxtrac/maxtrac-index.html
Introduction Info
http://www.repeater-builder.com/motorola/maxtrac/maxtrac-intro-stuff.html

HMN-3596A Schematic diagram
http://www.repeater-builder.com/motorola/maxtrac/pix/hmn3596a.jpg

HMN-3596 Full documentation
http://www.repeater-builder.com/motorola/maxtrac/pix/hmn3596-microphone.pdf
« Last Edit: July 30, 2013, 05:53:27 PM by W9GB » Logged
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