New NPR-H Modem Upgrades F4HDK's Original Design with On-Board Amps, Power Over Ethernet

Pseudonymous engineer Kuek has launched a new packet radio modem design for hams, based on the New Packet Radio NPR-H standard and compatible with firmware written for F4HDK's earlier design — but boasting a selection of improvements, including Power over Ethernet (PoE) support.

"I was amazed by the work of F4HDK. And as a ham radio guy who was active in packet radio in 1999 and the years beginning of 2000s I wanted to have something faster. Hamnet is nice, but you cannot have that long range transmissions as on 2m or 70cm bands," Kuek writes of his design. "The modem I build is compatible with F4HDK's hardware and firmware and can be used for ham radio guys as a standalone long range communication bridge, entrance to ham radio, bridge between networks, etc."

The primary new feature is an Ethernet support boasting Power over Ethernet (PoE) support, allowing the modem to send and receive data and be powered from a single cable — either using an Ethernet switch with PoE support or an optional PoE injector. Kuek's redesign also includes a low-noise amplifier (LNA) with 13dB gain, a power amplifier offering up to 25dBm output power plus GPIO pins for driving additional power amplifiers, and increased static RAM (SRAM) at 1kB.

"Unfortunately, the PoE part, SRAM, LNA and power amplifier increased the BOM [Bill of Materials]," Kuek admits. "But therefore you get performance. From the sales price, some USD per piece is donated to my ham radio club O28, depending on what's left after USD-EUR conversion, bank fees etc. Thanks for your support!"

The new radio is now for sale on Tindie priced at $135.98, while the design files are available on Hackaday.io — as are the files for F4HDK's original design.