Start a tune carrier to check SWR¶
Send a continuous carrier at reduced power to read SWR on your antenna system. Use this before a QSO or after changing antennas to confirm a good match.
Before you start¶
- AetherSDR must be connected to the radio. The TX Controls applet is only active with a live radio connection.
- Make sure you are clear to transmit on the frequency (the band must be open to your station legally).
- Set the tune power to a level appropriate for your antenna system. The default is 10; see Set tune-carrier power.
Steps¶
- Click the TX tray button in the right sidebar to open the TX Controls applet if it is not already visible.
- Check the Tune Pwr slider. The default is 10 (out of 100). Adjust if needed before transmitting.
- Click TUNE.
- The button label changes to TUNING... and the button background turns red while the carrier is active.
- The SWR gauge updates in real time. The scale runs from 1.0 to 3.0; readings above 2.5 are shown in red.
- The RF Pwr gauge shows forward power at the exciter output.
- Read the SWR value from the SWR gauge.
- Click TUNE again to stop the carrier.
- The button label returns to TUNE and the red background clears.
What each control does¶
| Control | Kind | Default |
|---|---|---|
| TUNE | Push button | — |
| Tune Pwr | Slider | 10 |
| RF Pwr | Meter | — |
| SWR | Meter | — |
Tips¶
- Keep Tune Pwr low (10 or less) when testing an unknown antenna system. Raise it only after confirming a reasonable SWR.
- The SWR gauge turns red above 2.5. If it pegs at 3.0, stop the carrier and check your feedline and antenna connections before continuing.
- To run the internal ATU instead of checking SWR manually, click ATU after the tune carrier confirms the antenna is usable. See Run the internal ATU.
- If you want to inhibit specific TX outputs (ACC TX, TX1, TX2, TX3) during tuning, configure them at
Settings > Inhibit during TUNE.
ATU button behavior (v0.9.5.1)¶
Starting with v0.9.5.1, the ATU button behaves as a frequency-aware toggle rather than always starting a new tune cycle. The logic mirrors SmartSDR's per-frequency behavior:
- First click (or after a frequency change) — Starts a fresh ATU tune cycle.
- Second click at the same frequency — If the ATU has already reported a successful match (Success or Mem indicator lit) and the transmit frequency has not changed since that tune, clicking ATU switches the tuner to bypass instead of starting another cycle.
- After any frequency change — The saved tune frequency is cleared. The next ATU click always starts a fresh tune cycle, even if the previous result was successful.
When the ATU enters bypass, the tuned-frequency record is also cleared, so the next click will start a fresh tune regardless of frequency.
This change has no effect on the MEM button or the ATU status indicators (Success, Byp, Mem), which continue to behave as described below.
MOX and Quindar tones (v0.9.7)¶
Starting with v0.9.7, clicking MOX routes through the Quindar-tone coordinator rather than keying the transmitter directly. When the QUIN chip is enabled in the Audio Channel Strip and the active TX slice is on a phone mode, the K-tone plays on PTT engage and the BK-tone plays on PTT disengage. When Quindar is disabled or the active TX slice is not on a phone mode, the behavior is identical to previous versions.
This change affects only the MOX button in the TX Controls applet. Hardware PTT, VOX, and other PTT sources are not affected.
Troubleshooting¶
- TUNE button does nothing — The applet requires an active radio connection. Check that AetherSDR shows the radio as connected before attempting to transmit.
- SWR gauge does not move during TUNE — Forward power may be at or near zero. Verify the Tune Pwr slider is above 0 and that the correct antenna port is selected for the current band.
- Carrier does not stop — Click TUNE once more. If the button remains in TUNING... state, check the radio connection; a dropped connection can leave the transmit state unacknowledged.
- ATU button bypasses the tuner instead of retuning — This is expected behavior when the ATU already holds a successful match at the current frequency. Change frequency or wait for the tuner to clear its result, then click ATU again to start a fresh tune cycle.
- MOX keys the transmitter but no Quindar tones are heard — Confirm that the QUIN chip is enabled in the Audio Channel Strip and that the active TX slice is set to a phone mode (USB, LSB, AM, FM, or similar). Quindar tones do not play on CW or digital modes.