MMDVM Duplex Hotspot Module Dual Hat V1.5.2 with 0.96 OLED Display Support P25 DMR YSF NXDN DMR Slot 1 + Slot 2 for Raspberry Pi, Pi Zero (with OLED)

Duplex means it’s meant to have an offset for TX and RX. Also one is TX only and the other is RX only. It will not listen to two modes at the same time or allow you to listen to one mode and TX at the same time, and it will not allow you to monitor two D-Star reflectors at the same time. It will allow a more natural “repeater” like operation, it will allow you to have both time slots in DMR (can monitor two different talkgroups at the same time. I’m happy with it overall however if I were to read/watch a decent review of it and knew what it can’t do (as I stated above) I probably wouldn’t have purchased it. I would really prefer (I’m probably wishing here and it’s probably not possible period) to have a dual receive mode where I can listen to 1 DMR talk group and 1 D-Star reflector at the same time…but it can’t. Would also be nice if it could act as a (cheap) actual repeater for public use. But it’s meant for digital mode personal hotspot use. Also, I should’ve paid the couple bucks more for the one with the attached screen. The nice thing as I stated above is now I have both DMR time slots, and it acts just like a repeater with a +5Mhz split “just like a real repeater”. Also, it runs just fine on a PiZero. If you bought a ZUMSpot or a cheapie Chinese copy, you can swap hats and make a few simple changes and be right back up again in less than 10mins. You will need to add programming to your DMR radio. I had to change my channels to use a +5Mhz split, and to get both time slots I also added another “Zone” and copied all the channels that I was already set for, however one zone is time slot 1, and the other is time slot 2. Same channels, same RX & TX frequencies, only needed to change the time slot settings. But now I can have both bands on my AT-D878UV going, with band one zone using time slot 1 and band two using the zone for time slot 2. I’m sure there are other ways to accomplish the same thing, just sharing what I did.

Works very we with DVM Host in the 900 Ham bands. Very nice quality as well.

Great MMDVM Hotspot! It just keeps on working day after day. Works great with all digital modes I've tried! DSTAR, YSF, P25, DMR, & NXDN! I use this single Hotspot with multiple protocol radios simultaneously to monitor activity. One cannot use more than radio at a time, however, but that is not a fault of the MMDVM. for that use case, it would require a dedicated MMDVM for each protocol.

I will not buy MMDVM hats from another source. Other sources were inconsistent and some didn’t work. This one came ready to go with great instructions for Pi-star. I’ve ordered more.

Works Great – Just Follow a Few Key Tips I was a little nervous after seeing some reviews mentioning defective boards, but mine works perfectly. I’ve found that success really comes down to a few things: – Use the right power supply: Make sure you’re using a solid 5V power supply rated for at least 3.5A. Underpowered setups can cause all kinds of issues. – Avoid GPIO conflicts: At first, my OLED screen wouldn’t light up because I had a fan HAT installed on the GPIO pins. Once I removed the fan HAT, the OLED came on right away. So if your screen isn’t working, double-check that nothing else is sharing or blocking the pins. – Set up DMR and duplex correctly: The instructions can be a little confusing, but if you take your time, use some common sense, and have a basic understanding of Raspberry Pi and Linux, you’ll get it. I personally used ChatGPT to help clarify a few steps, and that worked really well for me. Overall, once everything was set up properly, the board worked exactly as expected. Disclaimer: I used ChatGPT to help make this review more clear and well-written.