After a year of assembling, programming, troubleshooting and tweaking, we recently put up a MMDVM (Multi-mode Digital Voice Modem) repeater for the south end of Davis County, UT. Last year I entered the world of digital voice with a purchase of an MD-380 digital DMR handheld radio. Since our area lacked good repeater coverage, I decided to try to build a repeater to help fill in some of the coverage gaps.
One of the hardest parts of putting a repeater on the air was simply getting a frequency coordination for the 70 cm band. The key pieces of the repeater are the actual MMDVM board that sits on an Arduino Due board. The Due is connected to a Raspberry Pi which runs G4KLX’s MMDVMHost software that interfaces with the MMDVM software on the DUE and connects the repeater to the Brandmeister DMR network. The radios are two Motorola CDM-1550LS+ radios connected via duplexer to a Diamond X-50A antenna.
Below are some pictures of the repeater: