Scenarios & troubleshooting

Jobs that cross several chapters. Each one names what you need before you start, the steps in order, what you should see when it worked, and what to do when it did not.

The per-section chapters stay the reference for one screen. This page is for the work that does not live on one screen: stopping a transmission, getting a dead receive path decoding again, arriving from another program, and running a station that is not the simple one-radio-online case.

Stop a transmission

When you need this: a transmission is going out and you want it off the air now — wrong frequency, wrong message, a stuck key, a neighbor on the phone.

Before you start: nothing. This is the one job in Nexus that has no prerequisites by design.

The rule

Every cockpit keeps at least one stop control on screen at all times. The ⊞ Panels menu can hide a great deal of a cockpit; it can never hide the last way to stop transmitting. That is enforced by a test that hides every panel in every cockpit, one at a time and then all at once, and looks for the stop controls by name.

Steps

1. Press Esc. In Operate, CW, RTTY, PSK and JS8 this stops the transmission from anywhere in that section — in Operate and CW it works even with the cursor in a text field. In Phone, release the space bar.
2. If Esc did nothing, press Stop TX in the cockpit header. It is never disabled and never hidden.
3. Drop the TX latch, where the cockpit has one on screen — the ▼ TX On / ■ TX Off control in the header of Operate, RTTY, PSK, JS8 and SSTV. This does not just cut the over; it disarms transmit, so nothing can start another one. Phone and CW arm elsewhere and have no latch in the header.
4. If a tune carrier is up, press Tune again. Tune is a toggle — the button reads TUNING… while the carrier is up, and the second press drops it. It also auto-stops on its own watchdog.

Expected result: the rig unkeys, the TX meters fall to zero, and the header’s TX indicator goes to off. In RTTY and PSK the continuous-TX latch drops too, so nothing you typed ahead goes out.

Which control is where

Every cockpit’s on-screen stop line:

Cockpit	Controls that stop a transmission
Operate (FT8/FT4)	Esc · Stop TX · TX Off · Tune
Phone	The PTT button (release) · space bar (release) · Stop TX · Tune
CW	Esc · Stop TX · Tune
RTTY	Esc · Stop TX · the dock’s Esc / Stop macro · the TX latch · Tune
PSK	Esc · Stop TX · the dock’s Esc / Stop macro · the TX latch · Tune
JS8	Esc · Stop TX · Tune
SSTV	Stop · the TX latch

Two stop controls live inside removable panes and can be hidden: Phone’s voice keyer ■ Stop, and RTTY’s Auto on toggle in the stream pane. Both are conveniences on top of the guarantee, not the guarantee.

If the rig is still keyed

A latched RTTY or PSK over has one more stop that nobody presses. Those two modes hold the transmitter up with no pre-computed end, so the engine re-checks every transmit gate continuously and drops the latch — not just the text feed — the moment one goes down. Leaving the section, a QSY out of your privileges, a tune, or a radio handoff each unkey it within a tick. That is a property of the continuous-TX latch; do not count on it in the other modes.

Otherwise:

1. Unkey at the radio. The rig’s own PTT, or its power switch, is the backstop and it always wins. Nothing in software outranks it.
2. A held mic PTT is not something Nexus can release. If the app says “Mic PTT is held”, the key is down outside the app: a stuck foot switch, a mic button, or a CAT-broker client holding PTT. Nexus deliberately does not override a held key.

If a stuck transmitter survived a Stop TX, that is a defect worth reporting — say which cockpit, which control you pressed, and what the header said.

The rig will not key

When you need this: you press send and nothing goes out, or a refusal message appears.

Before you start: know your callsign is set, and know which band and mode the rig is actually on.

Nexus refuses a transmission for one of a small number of reasons, and it always says which. Work down the list:

1. “TX locked — this frequency is outside your license privileges.” The dial and mode you are on are not permitted for your license class. Change band, or correct the class in Settings ▸ Station ▸ Operator & Radio. Under split, the message names the frequency it is judging — the transmit one, which is not the one you are listening on.

2. The TX latch is off. The header control reads TX Off. Click it on. Receive works with it off; nothing transmits.

3. Your callsign is not set. Every network- and air-facing path checks it. Settings ▸ Station.

4. Something else holds the transmitter. Nexus arbitrates one transmitter between eight owners, and names the one holding it:

   What it says	Who has it	What to do
   Another transmission is in flight — stop it first	The FT8/FT4 slot sequencer	Esc, or Stop TX
   Tune carrier is up — stop tuning first	The tune carrier	Press Tune again
   Mic PTT is held — release it first	A held mic key, yours or a CAT-broker client’s	Release the key at the rig
   A voice message is transmitting — stop it first	The voice keyer	■ Stop in the keyer pane, or Stop TX
   CW is sending — stop it first	The CW queue	Esc
   RTTY is transmitting — stop it first	An RTTY over, or the continuous-TX latch	Esc
   PSK is transmitting — stop it first	A PSK over, or the continuous-TX latch	Esc
   An SSTV image is transmitting — stop it first	An image in flight	Stop

5. The transmit watchdog tripped. A continuous-TX limit was reached and transmit auto-halted. Re-enable TX to clear it.

6. RTTY only, on the FSK backend: the data line and a serial PTT line are configured onto the same physical line. Fix it in Settings ▸ Digital ▸ RTTY.

Nothing refused and still no RF? Then the software thinks it transmitted and the problem is downstream. Use Prove TX on the Setup health strip in Settings ▸ Radio: it keys a ~2-second tune carrier to test the whole CAT → PTT → RF path, asks for confirmation first, and shows forward power while it keys. Have an antenna or dummy load connected. If Prove TX produces power and your mode does not, the fault is in that mode’s audio path or drive; if Prove TX produces nothing, it is CAT, PTT wiring, or the radio.

Nothing is decoding

When you need this: the waterfall is blank, or it looks alive but no text appears.

Before you start: know which sound card the radio’s receive audio arrives on.

1. Look at the waterfall first. Band noise should show as a moving floor. A flat, dead waterfall means no audio is reaching the app — this is a device problem, not a decoder problem. Go to step 2. A lively waterfall with no text means the decoder is not armed or is looking in the wrong place — go to step 4.
2. Check the input device. Settings ▸ Radio ▸ Audio ▸ Input Device (RX). The Live input spectrum on that page shows what the selected device hears; if it is flat there too, the device is wrong. Refresh re-scans, which matters after plugging a USB interface in.
3. Check the level. RX Level on the same page should read around 30 dB. Anything from about 15 to 60 dB decodes. Red is too hot — turn the rig’s audio output down. Under 15 dB, raise RX Gain until the meter comes up; the meter responds when you release the slider.
4. Check the section is armed. RTTY and PSK do not decode until their receiver is armed — see RTTY and PSK for what arms them and what the pane head shows when it is not armed. FT8/FT4, JS8 and SSTV decode without arming.
5. Check you are on the right frequency and mode. The rig has to be in a data mode with a wide enough filter, on the dial the mode expects. Settings ▸ Digital ▸ Working Frequencies holds the dial each mode starts on.
6. Check the clock. FT8, FT4, JS8, Tempo and the other slotted modes decode against UTC slots. The Now-Bar shows the clock offset; a machine more than a second or two out decodes badly or not at all. Fix it with the operating system’s time sync, not in Nexus.

Expected result: the waterfall shows a moving noise floor, RX Level sits near 30 dB, and decodes appear at the end of each period.

Move over from WSJT-X

When you need this: you have been running WSJT-X and want Nexus to be the station instead — or alongside.

Before you start: a copy of your existing log as ADIF, and WSJT-X closed if it is holding the same sound card and CAT port. Two programs cannot own one serial port.

1. Set your station up — callsign, grid, license class, rig, sound card. The first-run wizard covers all four.
2. Bring the log across. Import ADIF in the logbook takes a WSJT-X wsjtx_log.adi (or an export from any other logger). It adds contacts you do not have and applies confirmations and award credits to ones you do. A toast reports the two counts separately. See Logbook & QSL.
3. Point your existing tools at Nexus. If you run JTAlert or GridTracker, turn on WSJT-X UDP API in Settings ▸ Logging & Connectors ▸ Integrations & Feeds — default 127.0.0.1:2237, the address those tools already expect. For loggers that tail a decode file, turn on Write ALL.TXT decode log; it is written only while that is on, and the file first appears after the next decode.
4. Turn on your confirmation services in Settings ▸ Logging & Connectors ▸ Confirmations — LoTW, QRZ, ClubLog, eQSL, HRDLog. Then pull your confirmations down once; the first pull covers your whole history.

Expected result: your entity, band and mode counts in Awards & Journey match what you had. If they do not, the import is the thing to check first — Awards counts the local log and nothing else.

What is different from WSJT-X. The keyboard shortcuts match on the keys that matter (Esc, F4, F6, Alt+1–Alt+6), and F4 clears the DX call even with the cursor in a field, which is WSJT-X’s own behavior. See the keyboard reference.

Run two radios

When you need this: a second rig on the desk, or one rig for HF and another for VHF.

Before you start: each radio needs its own CAT connection and its own sound card. Add and route them in Settings ▸ Radio ▸ Radios — the roster, band routing, and which radio is ACTIVE.

The chapter that carries the worked example is Settings reference ▸ Radio. What matters for every other page: one transmitter is arbitrated at a time, and a radio handoff is one of the events that unkeys within a tick. If a transmission stops when you did not stop it, a band change or a handoff is the usual reason.

Run a club event

When you need this: Field Day, Winter Field Day, or any multi-operator event on one log.

Before you start: the class, section and exchange for your entry, set in Settings ▸ Contesting ▸ Field Day Setup; and, for more than one position, a host on the LAN in Settings ▸ Contesting ▸ Field Day Club Sync.

Both are written up in Field Day & POTA/SOTA. The cross-cutting pieces:

• The club band board tears off onto a second monitor or a TV, set in glance type because it is read across a tent rather than at the keyboard. See Windows you can tear off.
• The CW macros change during a Field Day event — the exchange set replaces the ragchew set. CW has both tables.
• Dupes are shared live. With club sync on, each position’s contacts stream to the host as they are logged, and the host pushes back the club-wide dupe list that drives the while-typing dupe warning. It is not a merge afterwards.
• The host is the only time Nexus listens beyond this computer, and only while the toggle is on. Contacts logged while the network is down re-send on reconnect, and hosting can move to any other position if the host PC dies.

Operate with the feeds down

When you need this: no internet at the site, or the cluster and PSK Reporter are unreachable.

Nexus is built so the station still works. What changes:

Still works offline	Needs a feed
Every mode: decode, transmit, log	The Needed board — every row is a spot or a reception report
The logbook, including edits and export	Spots — the raw cluster and RBN traffic
Awards & Journey — counted from the local log, no network at all	DXpeditions — the expedition list
Stats	Confirmation upload and download
Satellites pass prediction, from the orbital elements already downloaded	Fresh orbital elements — refresh them before you leave
Memories and Program channel lists you already have	Repeater lookups for a new location

Before you go: refresh the orbital elements (Settings ▸ Radio ▸ Orbital elements), the country file (Settings ▸ Logging & Connectors ▸ Country file (DXCC)), and the LoTW users list (Settings ▸ Logging & Connectors ▸ LoTW users list). All three are local files once fetched.

The Now-Bar’s feed-health pills tell “connected but quiet” apart from “down”, so a dead cluster reads as dead rather than as a quiet band.

Honest limits

• This page is not a substitute for the section chapters. It carries the cross-cutting path only; the control-by-control detail stays where the control lives.
• Nexus cannot release a PTT it does not hold. A stuck foot switch, a mic button or a CAT-broker client holding PTT is outside the app, and only the radio ends it.
• A refusal message is the app’s own reasoning, not a measurement of the air. “TX locked” means the software gate said no; it does not prove the rig did or did not emit.
• Nothing here has been verified against every rig. The CAT, PTT and amplifier paths differ per model, and several are documented as not verified on hardware.

Related guides

• Settings reference — every field, by tab
• Operate — FT8/FT4 digital — the cockpit most of these scenarios start in
• Logbook & QSL — import, export and the connectors
• Guide overview — the keyboard reference and the pop-out matrix