Pi-Star D-Star Hotspot, Part 1: Hardware, Assembly, and Installation

This three-part series walks through building a Pi-Star D-Star hotspot from parts to first QSO. Part 1 covers hardware choices, physical assembly, and getting Pi-Star onto the SD card.

Pi-Star ships as a ready-made image based on Raspberry Pi OS Lite — no desktop GUI. You do not install stock Raspberry Pi OS and Pi-Star separately unless you are doing advanced custom work. The supported path is to flash the Pi-Star image, boot, and open the web dashboard.

Hardware Recommendations

A working hotspot needs five things: a Raspberry Pi, an MMDVM board, a power supply matched to the Pi, an antenna appropriate for the frequency, and an optional display.

Raspberry Pi 5 vs Raspberry Pi Zero 2 W

Practical advice: For a D-Star desk hotspot, a Raspberry Pi Zero 2 W stacked on an MMDVM_HS hat is the default recommendation. A Pi 5 makes sense if you already own one or plan to run multiple digital modes with cross-mode enabled.

MMDVM Board Options

Modern hotspots use boards running MMDVM_HS firmware — the open-source design popularized by the MMDVM_HS_Hat project. You will see them sold under many names (ZUMspot-style boards, BI7JTA boards, AURSINC kits, Jumbospot clones). They are largely interchangeable if the firmware is current.

• Single-band UHF (70 cm) hat — Most common for US D-Star handhelds. Look for 430–440 MHz or “UHF.”
• Single-band VHF (2 m) hat — For 145 MHz simplex with a 2 m D-Star radio.
• Dual-band hat — Both bands on one board; useful if you operate VHF and UHF.
• Duplex hat — For true repeater builds. Personal hotspots use Simplex Node mode in Pi-Star.
• Legacy DV-Mega — Older but still supported in Pi-Star. Dual-band; larger form factor.

When you buy a board, confirm band (UHF vs VHF), expected TX/RX offset (most simplex hats are zero offset), and whether an OLED is included.

OLED and Display Options

• SSD1306 OLED (included on most hats) — 0.96-inch status display. Configure later in Pi-Star Display Options. On some boards the OLED only activates over Wi-Fi.
• Nextion TFT touchscreen — Larger color display on UART. Supported in Pi-Star; optional.
• No display — Perfectly viable. The web dashboard is the real control surface.

Antenna Options

• Bench testing — Handheld rubber duck a few inches from the hotspot antenna is fine for initial setup.
• Desk hotspot — Short 70 cm antenna (Nagoya NA-771, Diamond SRH770S) on the hat SMA connector.
• Fixed location — Small mag-mount on a metal surface can outperform a stubby on a shelf.
• Separation — Keep the antenna a few inches from the Pi board if using Wi-Fi; an SMA extension cable helps.

Power Supply Options

• Pi Zero 2 W — Quality 5 V / 2.5 A micro-USB (or USB-C on newer carriers).
• Pi 3B+ / Pi 4 — Official 5 V / 3 A USB-C (Pi 4) or 2.5 A micro-USB (Pi 3B+).
• Pi 5 — Raspberry Pi 27 W USB-C PSU (5 V / 5 A) with a proper cable.
• Enclosed cases — Ventilation matters; use the case fan header on Pi 4/5 if available.

Before You Start

1. Valid amateur radio license — Required for D-Star gateway access.
2. MicroSD card — 16 GB or larger, name-brand (Samsung, SanDisk).
3. Card reader — USB adapter for your PC or Mac.
4. Ethernet or Wi-Fi credentials — Ethernet is more reliable for first boot.

Physical Assembly

1. Seat the MMDVM hat firmly on the Pi GPIO header. Attach standoffs first if the kit includes them.
2. Connect the OLED ribbon cable if your hat ships with a separate display board.
3. Screw the antenna onto the SMA connector hand-tight.
4. If using a case, fit the assembly and confirm the Pi can breathe — enclosed Pi 4/5 builds need airflow.
5. Do not apply power until the SD card is inserted (next section).

Install Pi-Star (Raspberry Pi OS Lite Image)

Download the current Pi-Star RPi release from pistar.uk/downloads. As of mid-2026, use Pi-Star_RPi_V4.3.x for Pi 5 or Pi-Star_RPi_V4.2.x for older boards.

Step 1: Download the image

1. Open pistar.uk/downloads.
2. Download the Pi-Star_RPi zip for your hardware.
3. Extract the zip; confirm a .img file is inside.

Step 2: Flash the SD card

1. Install Raspberry Pi Imager or balenaEtcher.
2. Insert the microSD card.
3. In Imager, choose Use custom and select the Pi-Star .img. Do not flash stock Raspberry Pi OS.
4. Select the correct target drive. Double-check the drive letter.
5. Write and verify. Safely eject the card.

Step 3: First boot

1. Insert the microSD card into the Pi.
2. Connect Ethernet, or plan to configure Wi-Fi after boot.
3. Apply power. Allow two to three minutes for first-boot filesystem expansion and reboot.

Step 4: Reach the dashboard

1. On a computer on the same LAN, open http://pi-star.local/admin/.
2. If mDNS fails, find the Pi’s IP in your router DHCP list and browse to http://<ip>/admin/.
3. Default login: pi-star / raspberry. Change the password before exposing the hotspot to the internet.

Step 5: Wi-Fi (optional)

1. Use the Pi-Star WiFi Builder or the admin Wireless Configuration page.
2. Reboot after saving credentials.
3. Reconnect at http://pi-star.local/admin/.