Review on 📻 Hima MMDVM Hotspot Spot Radio Station+ Antenna+OLED+ Black Case: Supporting P25 DMR YSF D-Star UHF, WiFi Enabled Digital Voice Modem for Raspberry Pi-Zero W, Pi 3, Pi 3B+ by Jon Thompson

Thanks to several reviews indicating the correct modem is MMDVM HS_HAT_ (DB9MAT AT DF2ET) for Pi GPIO is, it was easy to set up. Ignore the included instructions for setting up WiFi, now you don't need it. Mine worked right away, no offset or jitter needed to be adjusted. It's slow on the Pi Zero but works well, but the Pi 3 handles the Pi Star much better. OLED Type 3 didn't work for me on the Zero and there is some discussion online about it. I didn't worry about troubleshooting as the display works on the Pi 3 and the overall experience on the 3 is much better anyway. Used Pi 3s are cheap. DMR and this AP have a steep learning curve, but it's pretty easy to fall behind quickly. Once you have your eureka moment, you'll wonder what it was all about.