The Hytera HP789 operates across UHF: 350-470 MHz; VHF: 136-174 MHz. Several band versions exist; which one to buy follows from the frequency assigned to your organisation. UHF passes between walls and obstructions more readily, which is why it is preferred inside buildings, industrial plants and dense urban areas. VHF carries further over open ground and water at the same power.

RF output power is UHF: 4W/1W; VHF: 5W/1W. More power is not automatically better: it extends range and shortens battery life at the same time. Teams working close to a repeater are usually served by the low setting, which also lengthens the shift.

Capacity is 1024 channels across 64 zones. A zone is a page of grouped channels — separate zones are defined for different sites, different shifts or joint working with another organisation. On a multi-site system that grows, this is what lets the channel plan be extended without a rebuild.

Battery 2850 mAh Li-ion.

Durability is documented to MIL-STD-810G. The MIL-STD-810 series covers drop, vibration, thermal shock, humidity and dust testing; on field equipment it is a measured result rather than a marketing claim.

Operating temperature range is -30°C ~ +60°C.

The digital protocol is ETSI-TS102 361-1,-2,-3 — the ETSI DMR standard. Basic communication with other manufacturers’ radios is possible in standard Tier II mode; advanced trunking, vendor encryption and fleet management features do not carry across brands.

The hazardous-area certification is Model range compliant with UL913. Certification is granted to the assembly of radio and battery: fit a standard battery, antenna or earpiece and the approval no longer applies, and the device may not be used in the hazardous area.

Which zone and gas group a device may be used in is read from the markings on its case; the classification of the area itself comes from the facility’s explosion protection document. The two must match.