HMN1035C (and other mics) to Railroad Spectra

[W3AXL]

Hi everyone.

I've gotten my hands on a spectra railroad model, and I've been trying to get an HMN1035c mic that I use for my MCS2000 to work with it.

So far what I've done is connect the 6-pin connector on the back of the radio to a female Rj45 socket, using the pinout of the mcs2000 microphone found on the site. I connected PTT to PTT, MON to Hangup, Mic Hi to Mic, and GND to GND. I also made sure to make a jumper from Mic Ground to PTT Reference.

So far, PTT works fine. However, the microphone doesn't seem to be working. Additionally, the radio will not transmit if I remove my MON jumper (a piece of metal wedged into the mic clip on the back.

This should work according to the information I found in other threads. Anyone know why this wouldn't be working?

[jackhackett]

Make sure you don't have it wired backwards. Moto likes to do things it's own stupid way and so they reversed the pin numbers from the way the rest of the world numbers them.

Looking at your mic plug, with the locking tab facing away from you and the cord coming out the bottom, pin 1 is on the right side of the plug.

[W3AXL]

I'll have to check. You would think if PTT works fine then the mic should be wired properly as well.

I'll keep playing with it.

[jackhackett]

You say PTT works fine, but you also say it doesn't transmit unless you short out the hangup button... that doesn't sound 'fine' to me. Reversed wiring would swap the PTT and HUB pins, which leads me to suspect the wiring may be reversed.
I may be wrong, but it's a common mistake due to Motorola's numbering scheme, and it's an easy thing to check before digging further into things.

Let us now either way, if that's not it we'll see what else we can come up with.

[W3AXL]

Turns out it was a combination of several things. The biggest one was that the pinouts I had were incorrect to begin with. Your advice on how the pins are actually numbered cleared that up right away.

The other was that a solder joint had broken in the connector, meaning the mic wasn't getting to the radio anyway.

Thanks for the help!

[jackhackett]

Great.
Glad to help.