Radioddity GD-77 / GD-77S
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| Frequency | TX: 136-174 MHz (VHF), 400-470 MHz (UHF) |
| TX power | 1 / 5 W (5W high / 1W low.) |
| Modes | FM (analog), DMR (Tier I and Tier II, dual time slot TDMA, Mototrbo compatible) |
| Battery | Li-ion 2200mAh / 7.4V |
| Weight | 260 g (9.2 oz) - ~260g with battery. Only 3 cm (30mm) body thickness. |
| Connector | SMA-Female on the radio body - takes SMA-Male antennas |
| Year | 2017 |
| antenna | SMA-Female on the radio body - takes SMA-Male antennas |
| speaker mic | Kenwood K1 style 2-pin |
| programming | programming cable (included) |
| charging | desktop charger (included) |
| power req | 2200 mAh 7.4V Li-ion battery (included). Desktop charger included. |
Estimated (unverified): AMATEUR (ham) radio - FCC Technician-class license required to transmit (2m/70cm); NOT GMRS, NOT license-free. Dual-band DMR (Tier I + II, dual time slot) + analog FM HT. 5W high / 1W low. 1024 channels. Stock contact database is small; the OpenGD77 open-source firmware (this is its REFERENCE platform) expands it to ~1 million DMR IDs and adds features - OpenGD77 needs its own CPS (not Radioddity's, not CHIRP). SMA antenna; Kenwood-style accessory. ~2017. Scarce as new (line winding down); strong used demand due to OpenGD77.
The radio OpenGD77 was designed for, with more forum posts, guides, and codeplugs than most budget DMR HTs. Build quality is a step above the DM-1801 (same chipset, nicer shell). OpenGD77 adds hotspot mode, satellite tracking, APRS, VFO mode. It has two customizable side keys, a clear backlit display, a 30 mm-thin body, and an included programming cable. Reviewers call it robust and capable with OpenGD77, and the advice is to install OpenGD77 before first use.
The stock firmware is poor; do not use it without OpenGD77. It is getting harder to find new (the DM-1801 is cheaper on the same chipset). No GPS, Bluetooth, or USB-C (desktop charger). No IP rating. 1024 channels. Only 5 W. The Radioddity GD-88 successor, a tier up, adds GPS, APRS, cross-band repeater, and SFR mesh. The AnyTone AT-D878UVII Plus is the premium upgrade path.
The OpenGD77 reference radio. The GD-77 with OpenGD77 firmware is how many amateurs got into DMR. The mix of affordable hardware, open-source firmware, and large community support let bargain radios rival alternatives costing several times as much. The GD-77 is getting scarce, but OpenGD77 lives on across the DM-1801, RD-5R, and other compatible platforms.
The Radioddity GD-77 is a budget dual-band DMR handheld that earned a special place in amateur radio for one reason: it is the reference platform for OpenGD77, a celebrated open-source firmware project. It is an amateur radio for the 2-meter and 70-centimeter bands and requires an FCC Technician-class license or higher to transmit; it is not a GMRS or license-free radio. It does both DMR (Tier I and II) digital and analog FM.
In stock form it is a capable 5-watt DMR radio with 1,024 channels, but its contact database is small, so it will not show every caller's name. OpenGD77 transforms it: the community firmware lets the radio hold the entire worldwide DMR ID database (close to a million contacts), adds features, and is widely regarded as making the GD-77 far more usable than the factory firmware ever was. Programming OpenGD77 requires its own software, separate from Radioddity's. The radio uses an SMA antenna and a Kenwood-style accessory jack.
It has become scarce as new stock, with Radioddity winding down the line, but it remains popular on the used market precisely because of OpenGD77. For a higher-end amateur DMR handheld, the AnyTone AT-D878UVII Plus is the step up; the budget Baofeng DM-1801 shares the same open-source firmware family.