Motorola SM50 node project

Hi everyone!

I am relatively new to the idea of ASL and I was wondering if I could get some help with my first AllStar project.

Recently, I’ve been given a lot of old wide band radios and one that I wanted to repurpose was a UHF SM50 as an ASL on a Pi 3B.

I’m not quite sure where to start. I have successfully realigned the radio for 440 MHz and plan on using it as a home-based repeater. I can’t remember how many watts it puts out, maybe 25 or 40, I can’t remember. Anyway, these radios have a 16-pin connector on the back for accessories, and I think this would be perfect for interfacing AllStar.

I am also unsure and uneasy with the CM108 method of PTT and audio. Is there any other way to interface PTT and audio?

I guess it all boils down to… where do I start???

Thank you all de KE0SBX

If you are skiddish on modifying a usb sound fob,
you can buy usb radio interfaces (URI) from a host of vendors.
I can’t advise on that as I do not use them, but I’m sure others will chime in.

If you get a pin-out for that radio, you should find all the necessary pins on the moto jack.
Pay attention to the audio type line/discriminator as your choice will affect the software settings.
I believe there is even a speaker out pin, but don’t remember. If you choose that it will need to be attenuated to a line level.

1 Like

Owen I strongly recommend the RA-35 series of interfaces from Masters Communications…
RA-35 Radio Adapter Interface Board - by Masters Communications You can probably find the 16 pin connector on eBay. URI Cables makes a cable but not knowing which pins they connect can’t say it will work on the SM50. The connector has everything you need, as you know. But the RA-35 has input for COS, PTT, Audio in, Audio out. If the computer you will use for Asterisk has a parallel port (printer) there is a way to use pins on that for COS and PTT, then audio in and out are the jacks on the USB sound FOB(CM108). If you are using a Raspberry Pi you have to go thru USB/URI.

Another point is that I don’t think you can duplex a SM50 to use as a repeater. Maybe two of them with a decent duplexer can do it. And keep in mind that depending on what you’ll be connecting to via Allstar the unit can approach continuous duty for some periods of time. So maybe cut power back a little and be sure to have a fan on the heat sink of the radio.

George W2DB

1 Like

Thank you for the tips and tricks!

I got HamVOIP/Asterisk installed last night really easy, but I might try reinstalling it again. Supermon isn’t working very well but that might be for a later post. The login doesn’t work too well.

I actually went ahead and bought a 2 pack of CM108s, in case I screw up soldering. I actually think I can do it, it just requires a lot of patience. By the way, does anyone know the modifications for this sound card? I’ve seen lots of variations online.

I guess if all else fails, I’ll look at getting one of the pre-made assemblies mentioned here.

Thank you again, we’re making some progress, and that’s better than nothing!

EDIT: Nevermind, my IP address in the config files was incorrect - supermon works great now! Also, I was pressing enter after typing in my password - found out that this doesn’t work well either.

Another question - what pins do I need to use on the SM50 for TX audio, RX audio, PTT, and COS/COR?

I think I figured out the pinout issues, I can set the radio for CSQ with PL/DPL for sensing COS. That should work.

Oh, and one more thing! I would like to power cycle (shutdown/reboot/restart???) my node at midnight every day. How do I do this on the HamVoIP version?

Thanks for the help again!

I’m back and done… for now…

I just used a simple crontab entry that called the shutdown -r command and set it to 12pm and 12am every day

I am not sure what the purpose of the automated shutdown is, but,
I want you to know there are other options depending on your need.

You can reload the dialplan - asterisk -rx reload
restart asterisk - systemctl restart asterisk

and simple - reboot

As you likely already know, but for others later reading this, shutdown in a bash script
shutdown -P now

Also see startupmacro in the wiki for getting setup what you want on fresh boot.

This topic was automatically closed 3 days after the last reply. New replies are no longer allowed.