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<h1>HF Networks</h1>
<h1>HF Nets</h1>
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 [http://wa8lmf.net/aprs/SSB_Frequencies.htm 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.   
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 [http://wa8lmf.net/aprs/SSB_Frequencies.htm 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.   


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<caption><h1>Current HF Packet Networks</h1></caption>
<caption><h1>Current HF Packet Nets</h1></caption>
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<td align="center">Name</td>
<td align="center">Name</td>
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<caption><h1>Proposed/Experimental HF Packet Networks</h1></caption>
<caption><h1>Proposed/Experimental HF Packet Nets</h1></caption>
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<td align="center">Name (Compatible NET)</td>
<td align="center">Name (Compatible NET)</td>
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<caption><h1>Proposed/Experimental HF Mixed Mode Networks</h1></caption>
<caption><h1>Proposed/Experimental HF Mixed Mode Nets</h1></caption>
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<td align="center">Name</td>
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With the overarching goal of linking systems statewide, we must also employ antenna systems that favor [https://en.wikipedia.org/wiki/Near_vertical_incidence_skywave NVIS] type propagation.  In general, this means horizontal (usually wire) antennas 1/8-1/4w wavelength above the ground or magnetic loops which are oriented vertically. For those interested in actual field strength tests, [https://www.w8ji.com/nvis_n_v_i_s_antenna.htm W8JI's NVIS page] shows the height to performance numbers.   
With the overarching goal of linking systems statewide, we must also employ antenna systems that favor [https://en.wikipedia.org/wiki/Near_vertical_incidence_skywave NVIS] type propagation.  In general, this means horizontal (usually wire) antennas 1/8-1/4w wavelength above the ground or magnetic loops which are oriented vertically. For those interested in actual field strength tests, [https://www.w8ji.com/nvis_n_v_i_s_antenna.htm W8JI's NVIS page] shows the height to performance numbers.   
For a quick reference, here are optimal antenna heights per band.  Conventional wisdom suggest NVIS primarily happens below about 10 MHz, though [https://ohiopacket.org/images/tmp/20M_NVIS.png real world testing] with a vertical magnetic loop at 3fe above the ground has yielded contacts well beyond groundwave, but well within NVIS ranges.  More experimentation may be needed to test it's feasibility on modes which require stronger signals.
For a quick reference, here are optimal antenna heights per band.  Conventional wisdom suggest NVIS primarily happens below about 10 MHz, though [https://ohiopacket.org/images/tmp/20M_NVIS.png real world testing] with a vertical magnetic loop at 3ft above the ground has yielded contacts well beyond groundwave, but well within NVIS ranges.  More experimentation may be needed to test it's feasibility on modes which require stronger signals.


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Revision as of 16:21, 27 May 2026

HF Nets

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 Nets
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
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

Proposed/Experimental HF Packet Nets
Name (Compatible NET) Band Center Frequency Speed Protocol Usage/notes Dial Frequency+Tone pairs
OH71018AX3 (NET40) 40M 7.101.8 MHz 300 Baud AX.25/FX.25 Intrastate Forwarding 7.101.0 MHz USB, 800 Hz (Recommended) | 7.103.5 MHz LSB, 1700 Hz
OH71028AX3 (NET40) 40M 7.102.8 MHz 300 Baud AX.25/FX.25 Intrastate Forwarding 7.101.0 MHz USB, 1800 Hz (Recommended) | 7.104.5 MHz LSB, 1700 Hz
OH71038IL2P3 (NET40) 40M 7.103.8 MHz 300 Baud IL2P Intrastate Forwarding 7.101.0 MHz USB, 2800 Hz
OH35965AX3 (NET80) 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 (NET80) 80M 3.598.5 MHz 300 Baud IL2P Intrastate Forwarding 3.596.0 MHz USB, 1500 Hz


The following networks are intentionally too far away in frequency to be compatible with NET105/NET40/NET80. The frequencies/tones selected exist just inside the Automatic Digital Control Station (ADCS) band edges in an effort to minimize co-channel interference. The dial frequencies are outside the ADCS range, but the audio tones are inside the range. Remote/unattended stations may wish to permanently reside here while local/attended may choose to QSY here for forwarding only. If you choose to run VARA and/or Mercury HF modems on the proposed dial frequencies, it is imperative that the bandwidth is limited to 500 Hz. This preserves the 250 Hz buffer between AX.25/FX.25 space tone (1100 Hz) and IL2P mark tone (1900 Hz). More importantly, it keeps the VARA and/or Mercury HF modems within the ADCS subband to allow legal automatic operation.

Proposed/Experimental HF Mixed Mode Nets
Name Band Center Frequency Speed Protocol Usage/notes Dial Frequency+Tone pairs
OH104005AX3 30M 10.140.15 MHz 300 Baud AX.25/FX.25 Intrastate Forwarding 10.139.15 MHz USB, 1000 Hz (Recommended) | 10.141.85 MHz LSB, 1700 Hz
OH1014065M 30M 10.140.65 MHz Various Mercury (500 Hz) Intrastate Forwarding 10.139.15 MHz USB, 1500 Hz (Fixed)
OH1014065M 30M 10.140.65 MHz Various VARA (500 Hz) Intrastate Forwarding 10.139.15 MHz USB, 1500 Hz (Fixed)
OH1014115IL3 30M 10.141.15 MHz 300 Baud IL2P Intrastate Forwarding 7.099.15 MHz USB, 2000 Hz
OH710015AX3 40M 7.100.15 MHz 300 Baud AX.25/FX.25 Intrastate Forwarding 7.099.15 MHz USB, 1000 Hz (Recommended) | 7.101.85 MHz LSB, 1700 Hz
OH710065M 40M 7.100.65 MHz Various Mercury (500 Hz) Intrastate Forwarding 7.099.15 MHz USB, 1500 Hz (Fixed)
OH710065V 40M 7.100.65 MHz Various VARA HF (500 Hz) Intrastate Forwarding 7.099.15 MHz USB, 1500 Hz (Fixed)
OH710015IL3 40M 7.101.05 MHz 300 Baud IL2P Intrastate Forwarding 7.099.15 MHz USB, 2000 Hz
OH710015AX3 40M 7.101.05 MHz 300 Baud IL2P Intrastate Forwarding 7.099.15 MHz USB, 2000 Hz
OH359515AX3 80M 3.595.05 MHz 300 Baud AX.25/FX.25 Intrastate Forwarding 3.595.15 MHz USB, 1000 Hz (Recommended) | 3.596.85 MHz LSB, 1700 Hz
OH359565M 80M 3.595.65 MHz Various Mercury (500Hz) Intrastate Forwarding 3.595.15 MHz USB, 1500 Hz (Fixed)
OH359565V 80M 3.595.65 MHz Various VARA HF (500Hz) Intrastate Forwarding 3.595.15 MHz USB, 1500 Hz (Fixed)
OH359615IL3 80M 3.595.05 MHz 300 Baud IL2P Intrastate Forwarding 3.595.15 MHz USB, 2000 Hz



NVIS Propogation

With the overarching goal of linking systems statewide, we must also employ antenna systems that favor NVIS type propagation. In general, this means horizontal (usually wire) antennas 1/8-1/4w wavelength above the ground or magnetic loops which are oriented vertically. For those interested in actual field strength tests, W8JI's NVIS page shows the height to performance numbers. For a quick reference, here are optimal antenna heights per band. Conventional wisdom suggest NVIS primarily happens below about 10 MHz, though real world testing with a vertical magnetic loop at 3ft above the ground has yielded contacts well beyond groundwave, but well within NVIS ranges. More experimentation may be needed to test it's feasibility on modes which require stronger signals.

Band Height
20M 8.25-16.5ft
30M 11.5-23ft
40M 16.5-33ft
80M 33-65ft
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