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Before You Transmit

Work through this checklist before you key up with AetherSDR for the first time, and again after a big change to your station, your computer or AetherSDR's settings. Each item says what to check and links to the page that explains it. Items marked (FlexRadio) apply only to a FlexRadio; the rest apply to every radio AetherSDR can transmit on.

The checks are written so you can do them without putting a signal on the air. Where you do need to transmit to check something, use low power into a dummy load or a clear frequency, and identify as your licence requires.

Requirements​

  • A radio that can transmit: a FlexRadio, a Hermes-Lite 2 or a recognised networked Icom. The ANAN-G2, RTL-SDR dongles, KiwiSDR/Web-888 receivers and the demo are receive-only. See Supported Radios.
  • AetherSDR connected to it. See First Connection.
  • A licence that covers the bands and modes you plan to use.

The checklist​

The radio and the transmit slice​

  • The right radio is connected. Its tab is active in the title bar, and it is not the demo ("Simulator (not on the air)"). See First Connection.
  • You know which slice transmits. The transmit slice has the red TX badge on its VFO. Switching the active slice does not move transmit; click a grey TX badge to move it. See Multi-Slice Operation and VFO Widget.
  • The transmit slice is on a frequency and mode you are licensed for. Check the band plan strip along the bottom of the panadapter. See Panadapter Controls.
  • Split is what you expect. If a red SPLIT badge shows, you transmit on the second slice, not where you are listening. Click the red SPLIT badge to end the split. See Split Operation.

Your station identity​

  • Your callsign is set in Settings → Radio Setup... → Radio → Callsign: (on macOS, AetherSDR → Preferences... → Radio). AetherSDR uses it for PSK Reporter, WSPR and spotting; on a FlexRadio it is also stored on the radio. See Radio Setup.
  • Your callsign and grid are set wherever a feature transmits them. AetherSDR has no single station grid; each feature that sends one has its own fields:
    • RADE Digital Voice end-of-over frames and FreeDV Reporter: SpotHub → FreeDV, Callsign (or Use radio) and Grid Square (or Use GPS). See SpotHub.
    • The WSPR beacon in Tools → PSK Reporter...: TX call: and Grid:. See PSK Reporter Map.
    • APRS in AetherModem Packet Radio: MY CALLSIGN, and GRID when the radio has no GPS fix.
    • D-STAR: MYCALL, which defaults to the radio's callsign. See D-STAR (ThumbDV).
    • Digital-mode programs such as WSJT-X use the callsign and grid in their own settings.

Microphone and transmit audio​

  • The microphone path is the one you mean to use. On a FlexRadio, Mic source in the P/CW applet chooses MIC, BAL, LINE, ACC or PC; for a microphone on this computer, choose PC. On a radio that takes its transmit audio over the network, such as a networked Icom, turn on PC Audio in the title bar. See TX Controls.
  • The computer's Input device is your real microphone, not a virtual device such as a DAX microphone. Check Settings → Radio Setup... → Audio. See Audio Settings.
  • The Mic level gauge in the P/CW applet moves when you speak.
  • AetherTX is set up, if you use a computer microphone. AetherTX shapes only a microphone on this computer. Open Tools → AetherTX..., check which stages are ticked, and set the Gate stage so it opens on your voice and closes between words. Use REC / PLAY to record and hear your processed audio without keying the radio. See Aetherial Audio.

Power, tuner and antenna​

  • RF Power and Tune Power are at sensible levels in the TX applet (both 0–100 %). Start low for a first test. See TX Controls.
  • (FlexRadio) The radio's power limits suit your station: Max Power on the Transmit page of Radio Setup, and per-band RF and tune power and PTT inhibit in Settings → TX Band Settings.... See Radio Setup.
  • The transmit antenna is the one you mean. The RX applet header shows the RX and TX antenna buttons, with the names you gave them in Settings → Radio Setup... → Antennas. See RX Controls.
  • The antenna is matched. Run the radio's ATU from the TX applet (FlexRadio), or your external tuner, at low tune power, and check the SWR gauge. A Tuner Genius XL has its own applet; see TGXL Tuner Control. Tools → Pre-tune ATU Bands... keys the transmitter repeatedly, so make sure the bands are clear first.
  • External amplifiers are in STANDBY until everything above checks out, and while you tune or sweep. The amplifier applets have STANDBY / OPERATE buttons; the PGXL has a STBY key. See Amplifiers and Peripherals.
  • (FlexRadio) TUNE will not key anything you don't want it to: Settings → Inhibit during TUNE ▸ chooses which outputs (ACC TX, TX1, TX2, TX3) are held while the radio tunes. See TX Controls.

Digital modes​

  • The program's audio route works. On Linux and macOS with a FlexRadio, DAX Virtual Audio gives each slice a virtual audio device. On Windows, and on radios without DAX, use the TCI Server. See WSJT-X Integration.
  • CAT or TCI control works before you transmit. Changing frequency and mode in the program should move the transmit slice in AetherSDR, and the program should key the slice you expect. See CAT Control and TCI Server.
  • (FlexRadio) The TX filter passes your tones. If AetherSDR shows a TX filter card on the panadapter when you transmit, widen TX Filter in the Phone applet. See TX Controls.
  • Your computer's clock is accurate. FT8 and similar modes fail when the clock is off by more than about a second. Keep the computer synchronised with NTP. AetherClock and GPS shows how far the computer's clock is from WWV/WWVB or the radio's GPS.

Keying paths and timers​

  • You know every way AetherSDR can be keyed. Check each one you have set up:
  • (FlexRadio) The radio's transmit time-out and interlocks are set: Timeout (sec): and the Interlocks - TX REQ group on the Transmit page of Radio Setup. See Radio Setup.
  • You can see when you are transmitting. A green M:SS transmit timer appears in the title bar, just left of PC Audio, for each of your own transmissions, and the VFO marker turns orange/red. If an interlock blocks transmit, a notification says why. See TX Controls.

First transmission​

  • The frequency is clear, or you are on a dummy load.
  • Press MOX (or your PTT) briefly at low power and watch the Fwd Power and SWR gauges in the TX applet. Unkey at once if the SWR is high or the power is not what you expect.

Troubleshooting​

The radio keys but puts out almost no RF in DIGU/DIGL​

The TX filter's low and high cut leave out your transmit audio.

  1. In the Phone applet, widen the TX Filter with the Low Cut and High Cut buttons until it covers your tones.
  2. Transmit again and check that the panadapter warning card no longer appears.

Transmit audio is missing with Mic source set to PC​

The computer's selected microphone is not your microphone, for example a virtual DAX microphone.

  1. Open Settings → Radio Setup... → Audio and choose your real microphone as the Input device.
  2. Check that the Mic level gauge in the P/CW applet moves when you speak.

Space or another key does not key the radio​

Operating keyboard shortcuts are off by default.

  1. Turn them on with Settings → Keyboard Shortcuts.
  2. Check the binding in Settings → Configure Shortcuts....

A notification says transmit is blocked​

An interlock is holding transmit off, for example an amplifier warming up, the ATU busy, or a band the radio does not allow.

  1. Read the notification for the reason.
  2. Wait for the amplifier or ATU to finish, or move to a band you may transmit on, then key again.

See also​