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Microphone differences
Posted: Mon Dec 06, 2004 5:17 am
by Dail Terry
Trying to find the difference between a HMN 1037 B and a HMN 1038 B Microphone.. I want to use the mic on a GTX Mobile.
TX
Dail
Posted: Tue Dec 07, 2004 2:19 am
by Will
HMN1037B DTMF mic
HMN1038B Base mic
Posted: Tue Dec 07, 2004 4:41 am
by kcbooboo
The GTX mobiles, at least those on 900 MHz, seem to use the same microphones as do MaxTracs and Radiuses, and probably GM300s. They all have an 8-pin RJ-45 style connector on them.
I'd like to say that any Motorola mike with this type plug will work with any of these radios, but don't hold me to this generalized statement.
Bob M.
Posted: Tue Dec 07, 2004 7:38 am
by Sam
OK, how about between HMN1001 (Mostar) and HMN1056 (Maxtrac)? I can get past the 6-pin/8-pin cable, and PTT works, but no audio. I assume they are both condenser elements by their size. Different voltage maybe? The 1056 is just too small and I'm too cheap to buy the 1035 for the Maxtrac...
Microphone differences
Posted: Tue Dec 07, 2004 3:58 pm
by odat
Maxtrac Mostar
3-Hook 3-PTT
4-Gnd 4-Mic audio
5-Mic audio 5-Gnd
6-PTT 6-PTT Gnd
Posted: Tue Dec 07, 2004 6:31 pm
by Sam
Yeah, I got the pinouts worked out, and PTT works okay, but there's no audio. I figure it must be a difference in the preamp circuits or bias voltage or something.
Oh well. Thanks anyway.
Posted: Wed Dec 08, 2004 3:13 am
by Will
The Mic input circuit has been the same since the Motrac days. (1964)
600 ohm with aprox. 8 volts on it fed from the radio. Typical audio level 120mV RMS.
You can easaly follow the pins and change the connector to the RJ45 8 pin connector, even tho there is only 6 wires. You only need 4 on a Maxtrac, Radius, GM, CDM, MCX ect.
Ground
Mic Hi
PTT
Mic hang-up stud
Posted: Wed Dec 08, 2004 4:12 pm
by Sam
OK, I found my problem - a bad RJ-45 jack I was using to build an adapter. It works fine now. Thanks, everybody.