How to write the RadioStar image to microSD and set up a hotspot in 10 minutes

RadioStar is a ready-made image for the Raspberry Pi (Raspberry Pi OS Lite + our agent) that turns a Pi with an MMDVM modem into a DMR hotspot on the DMRhub network. There's no need to fiddle with Pi-Star by hand, edit MMDVM.ini or hunt for a DMR ID — the image already does it all: on first boot it detects the modem on its own, configures itself and goes on air. All that's left is the easy part — writing the card correctly. Let's go through it step by step so it works the first time.

What you'll need

• Raspberry Pi — Zero 2 W, 3B/3B+ or 4 (an older Zero W works too, but the first boot will take longer);
• an MMDVM modem (MMDVM_HS_Hat, Dual Hat or a USB modem) and an antenna for the right band;
• an 8–16 GB microSD card — it must be genuine (SanDisk, Samsung, Kingston). Counterfeits with "AliFlash" kill the filesystem on the very first write;
• a card reader and a computer (Windows / macOS / Linux);
• a quality power supply, 5 V / 2.5 A or more and a data USB cable (not a "charging" one — those carry no data and often use thin wires → voltage drops).

Step 1. Download the image

Open the "Build image" page, pick your mini-PC and modem — you'll get a download link for the radiostar-pi.img.gz file (a single universal image, ~700 MB compressed). You don't need to download and unpack it manually — the flashing tools read .gz on the fly.

Step 2. Write the card

You'll need either of two free tools. Both read the compressed .img.gz — no need to unpack it in advance.

Option A · Raspberry Pi Imager (recommended)

1. Download and install Raspberry Pi Imager.
2. Insert the microSD into a card reader.
3. Launch Imager → Choose OS → scroll down to "Use custom" → select the downloaded radiostar-pi.img.gz.
4. Choose Storage → select your card (triple-check the letter/size — all data on the card will be erased).
5. Click Write. When asked about "apply OS settings / OS customisation", answer "No, no settings" — the image is already preconfigured, and extra Imager tweaks will only interfere with the agent.
6. Wait for writing and verification (~2–4 min). Done — eject the card.

Option B · balenaEtcher

1. Download balenaEtcher.
2. Flash from file → select radiostar-pi.img.gz.
3. Select target → your microSD.
4. Flash! → wait for writing and validation.

Step 3. First boot

1. Insert the card into the Raspberry Pi, fit the MMDVM modem on top, and screw on the antenna.
2. Apply power from a good PSU. The first boot takes 60–120 seconds — the image expands the filesystem to the full card capacity and brings up the services. Don't pull the power during this time.
3. The hotspot will bring up its own Wi-Fi network RadioStar-Setup. Connect to it with a phone or laptop — the setup page will open (if it doesn't open by itself, go to http://10.10.10.10).
4. Select your home Wi-Fi, enter the password — the hotspot will switch over to your network.
5. Sign in with your DMRhub account. The agent will detect the modem on its own, write MMDVM.ini, obtain a DMR ID and join the network.
6. Done: the hotspot is online and managed right from your portal dashboard — frequencies, talkgroups, over-the-air updates.

If something goes wrong