Upgraded MMDVM Hotspot Digital Voice Modem with OLED Display & WiFi - Supports P25, DMR, YSF - Compatible with Raspberry Pi Zero - Perfect for Amateur Radio, Emergency Communication & Digital Voice Networks

I spent three hours trying to make the unit boot up. This unit, when functioning properly, will display the MMDVM logo and other information on the screen when it finishes booting up, which will not take more than about thirty seconds.Three hours later, I determined that the TF card sometimes does not work. I discovered this when I inserted the card into my Android tablet. After several insertions, the tablet finally recognized the TF card. I then immediately removed the TF card from the tablet and inserted it into the hotspot. It booted up properly.If you then disapply and reapply power to the hotspot, the unit may or may not boot up and show information on the screen. If you insert the TF card repeatedly into a TF card reader, such as the one in my tablet, the tablet will eventually recognize the TF card. The card may then be inserted into the hotspot and will boot normally.Verdict: Junk. If you buy this product, there is a 50% chance that you will return it, due to an intermittently faulty TF card.Update: The seller was kind enough to send a replacement TF card with the latest software installed. The hot spot booted up properly. The hot spot began transmitting its wifi network and my tablet connected to it. I then pointed my browser to the hot spot's ip address. I could immediately log into the pi-star web interface on the hot spot and configure the hot spot, to include information regarding the local wifi network that I want the hot spot to connect to. I restarted the hot spot and it connected to my local wifi network. A few hours later, after hurriedly learning about Brandmeister and choosing talkgroups of my liking, I was transmitting and receiving on talkgroup 91, Worldwide.The functioning of the hot spot is excellent, the audio quality is excellent, and my handy talkie will reliably transmit to, and receive from, the hot spot from a hundred feet away though it may turn out to be more.It appears that the seller may have received a bad batch of TF cards. Again, the seller quickly sent me a new one.This product is excellent and I highly recommend it. I will likely purchase another to have as a ready backup. It is easy to download the hot spot's configuration and upload it to another of the same model.