HFNets

The following index has been created to track various efforts to utilize the HF bands for node hopping and mail forwarding. There are some existing networks that are primarily focused on casual operating, keyboard to keyboard messaging for personal mail delivery. Due to the nature of AFSK and SSB, it is possible to have many combinations of VFO dial frequency with audio tone selection. Please see WA8LMF's excellent article on their relationship. It is also possible to run multiple, concurrent modems as long as their audio pass range fits within the radio's SSB filter. These ranges can vary, but generally runs around 300-3000 Hz. The two most popular protocols are AX.25/FX.25 (compatible) and IL2P. The AX.25/FX.25 protocols use NRZI encoding, which means USB and LSB can communicate as long as the center frequencies match. The IL2P protocol uses NRZ encoding, which means sideband selection must match. The seeming standard for HF IL2P seems to be USB. For compatibility reasons, it is suggested to run USB for both AX.25/FX.25 and IL2P. This also aligns with VARA, ARDOP and Mercury modems using USB. Traditionally, AX.25 HF packet was LSB by convention, but can support both. For those running hardware based TNCs that do not support IL2P and have fixed tones at 1600:1800 Hz (1700 Hz center), LSB frequencies are provided.

Current HF Packet Networks

Name	Band	Center Frequency	Speed	Protocol	Usage/notes	Dial Frequency+Tone pairs
NET105	20M	14.103.3	300 Baud	AX.25/FX.25	Keyboard to Keyboard	14.102.0 MHz USB, 1300 Hz (recommended) | 14.105.0 MHz LSB, 1700 Hz
NET105	20M	14.104.3	300 Baud	IL2P	Keyboard to Keyboard	14.102.0 MHz USB, 2300 Hz
NET40	40M	7.102.3 MHz	300 Baud	AX.25/FX.25	Keyboard to Keyboard	7.101.0 MHz USB, 1300 Hz (recommended) | 7.104.0 MHz LSB, 1700 Hz
NET40	40M	7.103.3 MHz	300 Baud	IL2P	Keyboard to Keyboard	7.101.0 MHz USB, 2300 Hz
OH71018AX3	40M	7.101.8 MHz	300 Baud	AX.25/FX.25	Intrastate Forwarding	7.101.0 MHz USB, 800 Hz | 7.103.5 MHz LSB, 1700 Hz
OH71028AX3	40M	7.102.8 MHz	300 Baud	AX.25/FX.25	Intrastate Forwarding	7.101.0 MHz USB, 1800 Hz | 7.104.5 MHz LSB, 1700 Hz
NET80	80M	3.597.0 MHz	300 Baud	AX.25/FX.25	Keyboard to Keyboard	3.596.0 MHz USB, 1000 Hz (recommended) | 3.598.7 MHz LSB, 1700 Hz
NET80	80M	3.598.0 MHz	300 Baud	IL2P	Keyboard to Keyboard	3.597.0 MHz USB, 2000 Hz
OH35965AX3	80M	3.597.5 MHz	300 Baud	AX.25/FX.25	Intrastate Forwarding	3.596.0 MHz USB, 500 Hz (Recommended) | 3.598.2 MHz LSB, 1700 Hz
OH35965AX3	80M	3.598.5 MHz	300 Baud	IL2P	Intrastate Forwarding	3.596.0 MHz USB, 1500 Hz