Welcome to a new project video, today I’m gonna be presenting this compact UHF repeater that I built recently and the story starts earlier this year when I got my HAM radio license and since I only have this baofeng radio, I was limited to the range and functionality of this radio or this local community maintained repeater for a national network which sometimes was offline or sometimes because of my location I couldn’t get a good signal. Hence why I decided to build a repeater.
To give you a general idea of how the whole system works, this repeater has an analog radio side which interfaces to your radio via UHF or VHF depending on the type of radio module you use. On the other end, you need a way of interfacing that analog radio traffic to a digital network that interconnects similar nodes into a big network.
That part is usually handled by a SBC, single board computer and people have used raspberry pi’s for that but there are also alternatives based on orange pi single board computers, like the one that I built here. Depending on the cost of these SBCs, their availability and the software that you plan to run, you might have good reasons to choose one or the other.
For example I really wanted to load a ready made, functional, OS image on my repeater, so I don’t have to manually install and configure everything. The nice people from the Rolink community have done the hard work and built this orange pi zero OS image which contains everything you need so it made sense for me to design my repeater based on an orange pi zero because that meant less software work for me. The software that runs on the orangepi zero and makes everything possible is Svxlink and this is open source software which evolved from the old echolink software. I encourage you to checkout their webpage to learn more about it but for the purpose of this video all you need to know is that it handles the interconnect to and from the network turning your simple node into a repeater.
In terms of repeater hardware, the most popular radio module is the SA818 manufactured by NiceRF a Chinese manufacturer and if we take a quick look at the datasheet we noticed this is a small compact walkie talkie module, it contains everything needed to accomplish walkie talkie functionality up to 1W output power. It comes in 3 different frequency ranges, I opted for the UHF version 400-480MHz range, but you can choose that based on your radio capability or how crowded the local traffic is. The module can be purchased for cheap from Aliexpress, directly from the NiceRF shop and they provide excellent support, for example they have emailed me the datasheet immediately after purchasing the module. Links for this are in the description below.