The N3VEM Repeater
It’s dawning on me that I’ve never really written about the fact that for a few months, I’ve officially been a member of the ‘repeater owner’ club. The saga actually began a number of years ago, when one of the offices at my work was getting rid of a repeater. It’s a long story about how that came about, but at the end of the day, they were getting rid of it, so I saved it so it could see a second life on the amateur bands.
The actual repeater in question is a Motorola GR1225 (UHF version), which were fairly common ‘desktop repeaters’ that were in use in quite a few businesses. As cell phones took over the niche they filled, they seemed to become readily available on the used market. Even if you don’t luck out like I did and save one that was bound for the trash, you can usually find them on Ebay for just a few hundred dollars.
Anyway, the repeater sat on the floor of my home office, unused, for a several years, because I wasn’t quite sure how I wanted to press it into service. In our area, 70cm isn’t super popular, and most of the 70cm repeaters sit quiet, so I wasn’t in a hurry to just stick it on the air to add yet another unused 70cm machine.
Within the last year or so however, the Ham Radio Workbench crew started talking about setting up an Allstar hub, which they did (node 55915). It was at that point that I said - heck, I have an unused repeater sitting on my floor - why not put it on the air, add Allstar capabilities to it, and have it hang around connected to their hub?
And so the project began…
Repeater coordination councils are all volunteer, so this takes some time! In my case it took about ~5 months from application, until I was assigned my frequency pair by the council that coordinates my area. While I waited, I did start ‘construction’ but just put the repeater on the air uncoordinated, with a low-to-the ground antenna, on a frequency pair that was unused in the area.
Since the machine is a desktop repeater, construction wasn’t too involved - just a few steps:
- Tuning the duplexer, which I did twice - once while I was uncoordinated, and then once again when I was assigned my final pair. W2AEW has a bunch of great videos on his youtube channel. I don’t have a ton of fancy equipment, but I think I got pretty decently tuned with my nano VNA, following this video specifically, to guide me along the way. As a note, since this is a desktop repeater, it only has the notch-type ‘portable’ duplexer, which works fine running here at my house, since I’m the only source of RF :-)
- Audio interface for Allstar - since this is a Motorolla repeater, I was able to use one of the RIM-lite interfaces from repeaterbuilder, which plugs directly into the back of the transciver, and in turn accepts the USB cable. I had to fiddle with some of the settings in the radio software, but it really wasn’t too difficult to get up and running.
- Allstar Node - pretty straightforward stuff here too - Raspberry Pi3, running Allstarlink. There seems to be some contention in the Allstar world, between Allstarlink and Hamvoip. At the time I went with Allstarlink because it seemed like the one that was more “open” and it sounds like there is some stuff in Hamvoip that might be slightly borderline as far as software license legality goes (Although I was more concerned about openness that software licenses - In some cases I firmly believe that piracy is the moral thing to do). I didn’t dig deep into it though, so do your own homework:-)
In hindsight, I’m glad I went with Allstarlink. This is because it runs on Debian, and I was able to fairly easily install node-red along side it. Hamvoip runs on Arch, which seemed way more fiddly when I played around with it recently.
- Node-RED - as mentioned, I installed Node-RED alongside Allstarlink, and I’m using that to schedule and fire off announcements etc, instead of the macros and scheduler that are built into both Allstarlink and Hamvoip.
- Antenna - Nothing too fancy here - jut a Diamond X50NA, on a mast at the eve of my house, with a fairly direct run of LMR400.
I’ll dabble with this for a while on a small scale, and if I find I enjoy the whole repeater-ownership thing, I’ll probably start working on upgrading at some point down the road. Some of this would require re-applying for updated coordination, but the things I’d probably want to explore would be:
- Getting the Antenna higher, once I put up a proper antenna, or find a cheap/free place to move the machine too, instead of my house.
- Switching to hard line (les loss, etc. etc.)
- Getting my hands on some proper notch/pass cans for better filtering/isolation
- An external PA maybe - I have the machine on low power - it’s capable of more, but this model is known for blowing finals when run at any fairly high duty cycle on their high power setting.
Anyway, that’s the story for now, and I’m having fun dabbling around with it!
There is a page specifically with info on the repeater, so make sure to check that out as well!