Nexus uses a new waveform (TempoFast / TempoDeep — the Tempo chat layer protocols), so it must not transmit on the established FT8 / FT4 / JS8 / WSPR / PSK watering holes — it would QRM them and they would QRM it. Nexus therefore ships its own calling frequencies, chosen to sit clear of every existing narrowband convention while staying inside the operator's legal sub-band.
These are proposed, editable defaults — not regulatory channels. They are a starting point to coordinate with the digital community. In the app you can pick any band with one tap or enter any frequency manually (TopBar and Settings). New modes that squatted on existing watering holes caused real friction, so community buy-in matters. Nexus deliberately avoids every established watering hole.
- HF — "upper shoulder of the digital cluster." On each band the dense block (FT8 → JT65 → JS8 → FT4) runs from the FT8 dial up a few kHz. Nexus sits just above that block and below the fragile ~200 Hz WSPR window, inside the IARU narrowband-modes segment. This is exactly how JS8 was sited relative to FT8 — Nexus takes the next clear notch up.
- VHF/UHF — two tracks. A USB weak-signal calling frequency in the bottom-of-band weak-signal segment (for all-mode rigs, like VHF FT8), and an FM-simplex data channel in a band-plan digital/experimental segment (for the FM HTs most off-grid operators carry). Both are offset well clear of the FM national simplex calling frequencies (146.520 / 446.000 / 223.500–223.540), APRS, satellite sub-bands, and repeater splits.
Nexus is USB with ~1500 Hz audio, so the emitted RF sits ~1.5 kHz above the dial. Every frequency below was checked, on the emission, to be:
- Inside US General-class privileges — the General data sub-bands on 80–10 m, full privileges on 160 m / 6 m, and band-wide data above 50 MHz. None land in Extra-only slivers or phone segments. (General is the reference; Extra is a superset. There is no Technician HF data access — 10 m and 6 m are the Technician-accessible Nexus frequencies.)
- Clear of CW — above the CW portion of each band and clear of the QRP / SKCC / FISTS CW calling frequencies.
All dials are USB suppressed-carrier; the emission sits ~1.5 kHz higher, and every gap below is measured to that emission. General data sub-band edges shown where relevant.
| Band | Nexus dial (MHz) | Nearest watering holes / edges (gap to emission) | Notes |
|---|---|---|---|
| 160 m | 1.8460 | above the whole FT8/JS8 cluster (≤1.843); JS8 1.842 (+5.5 k); PSK31 1.838 | tight band — keep audio low |
| 80 m | 3.5935 | PSK31/RTTY hole 3.580–3.590 (+5 k); data edge 3.600 (−5 k); FT8/FT4 3.573/3.575 | between the RTTY hole and the band/phone edge |
| 40 m | 7.0430 | QRP CW 7.040 (−4.5 k); FT4 7.0475 (+3 k); FT8 7.074 | IARU NB segment; in the CW↔FT4 notch |
| 30 m | 10.1425 | FT4 10.140 / PSK 10.141 (−3 k); edge 10.150 (+6 k); FT8 10.136 | secondary band — tread lightly |
| 20 m | 14.0905 | cluster 14.074–14.083 (−9 k); WSPR 14.0956 (+3.6 k) | the flagship ".09 shoulder" |
| 17 m | 18.0955 | FT8 18.100 (+3 k); QRP CW 18.096 (−1 k); FT4/JS8 18.104; WSPR 18.1046 | cramped — below the FT8/FT4/JS8/WSPR pileup; TempoDeep (50 Hz) only |
| 15 m | 21.0905 | JS8 21.078 (−14 k); WSPR 21.0946 (+2.6 k); FT4 far at 21.140 | |
| 12 m | 24.9115 | FT8 24.915 (+2 k); SKCC CW 24.910 (−3 k); FT4 24.919; phone edge 24.930 | cramped — in the SKCC↔FT8 notch; TempoDeep (50 Hz) only |
| 10 m | 28.1000 | cluster 28.074–28.080 (−20 k); PSK 28.120 (+18 k); FT4 28.180 | roomy — Technician-OK (≤200 W) |
| Band | Nexus freq (MHz) | Mode | Sits clear of | Notes |
|---|---|---|---|---|
| 6 m | 50.3450 | USB | FT8/JS8/MSK cluster (ends ~50.328), 50.620 | Technician-OK |
| 2 m | 144.2350 | USB | SSB call 144.200, FT8 144.174, beacons 144.275+ | weak-signal segment |
| 2 m | 145.5600 | FM | 146.520, APRS 144.39, sat 145.8+ | 145.5–145.8 experimental seg |
| 1.25 m | 223.5600 | FM | 223.540 FM call (+20 kHz), voice-simplex below | 223.52–223.64 digital seg |
| 1.25 m | 222.1300 | USB | 222.100 call, FT8 222.065 | weak-signal alternate |
| 70 cm | 432.4500 | USB | SSB call 432.100, sat 435–438, beacons 432.3–432.4 | mixed-mode segment |
| 70 cm | 445.9500 | FM | 446.000 call | ⚠ local-option only — check your coordinator |
- Proposed + editable. Coordinate with the community before treating any of these as "the" Nexus frequency; the app lets you override any dial.
- Dial vs emission. All HF/USB values are suppressed-carrier dial frequencies; the emission is ~1.5 kHz higher. On tight bands (160 m, 17 m, 12 m) verify your audio offset keeps the signal inside the segment and below the band edge.
- Region differences. Picks are framed for the US (FCC/ARRL). IARU R1/R3 band plans differ — notably 40 m / 80 m digital edges and the VHF SSB calls (144.300 vs 144.200, 432.200 vs 432.100) and APRS (144.800 vs 144.390). R1/R3 operators must re-vet against their national plan.
- FM channels are segments, not assignments. The exact 20 kHz slot within the 2 m experimental (145.5x) and 1.25 m digital (223.5x) segments — and especially the 70 cm 445.95 pick — should be brought to a regional frequency coordinator.
- Omitted: 60 m (channelized — no clean slot; FT8 already uses 5.357) and 33 cm / 23 cm (sparse; easy to add later).
- Cramped bands. 17 m and 12 m have data windows only ~42 / 40 kHz wide with FT8/FT4/JS8/WSPR packed at the top, so there is no clean ≥2–3 kHz notch: the Nexus dials (18.0955 / 24.9115) sit in the small gap below the FT8 cluster and above the CW calling spots (QRP CW 18.096, SKCC 24.910), leaving only ~1–3 kHz on one side. Use TempoDeep's ~50 Hz variant on these bands — a ~150 Hz TempoFast signal does not fit cleanly — and listen before transmitting.
- US General-class HF data/phone sub-band edges: ARRL US Amateur band chart / Frequency Allocations (arrl.org/frequency-allocations).
- Conventional dial frequencies (FT8/FT4/JS8/WSPR): WSJT-X default Working Frequencies; cross-checked against k7uv.com/digitalfreq.html and dxzone FT8 list. PSK31/RTTY watering holes: qsl.net/sv1grb, AA5AU RTTY sub-bands.
- VHF/UHF segments (6 m / 2 m / 1.25 m / 70 cm): ARRL National Band Plan (arrl.org/band-plan). 60 m channels: ARRL 60 m channel allocation.
- Band selector (TopBar and Settings): grouped HF / VHF / UHF channel list — one tap jumps the rig to that band's Nexus frequency and mode.
- Manual entry: type any dial frequency (MHz) and pick USB/FM; Nexus retunes
the rig live (via
rigctld/CAT) and labels the band automatically.