TX/RX Level Optimization for WSJT-X : Revisited

I decided to take another look at how to better set receive and transmit levels for digital radio modes.

In one of my inaugural posts I used the procedure listed by my radio’s instruction manual to set the transmit and receive levels for AFSK digital mode operation. What was notable was that the procedure listed in the manual went against the current general consensus for AFSK modes. While I don’t currently have the equipment to test the myths properly, I did have other people look at my signal using their panadapter and none thought the signal looked dirty in any way using Yaesu’s suggested settings running the radio at full power. I also heard and successfully decoded many DX stations using FT8 with AGC set to “Fast” and the RF gain set to 100% so that the AGC would be controlling the level continuously. I’m currently up to 101 DXCC worked since the beginning of this year so clearly none of the settings are preventing me from communicating effectively even using weak signal modes on the margins of what is technically possible.

That said, it still bothered me and I thought it really wouldn’t be that hard to just set my levels in a way that would maximize output and eliminate ALC/AGC triggers just to be able to eek out any potential theoretical performance gains mentioned in the WSJT-X documentation. Well, it wasn’t hard, but it also wasn’t a no brainer to set the levels so I came up with the following procedure and it is working as well or better than my previous settings.

RX Settings: (WSJT-X)

  1. Set the OS audio device TX/RX IO to 100% (aka 0 dB)
  2. Set physical audio device (SCU-17, SignaLink, etc.) levels to 50% if applicable.
  3. Disable the radio AGC and any DSP filters/processing.
  4. Set the radio mode to DATA
  5. Set RF gain to roughly 45%
  6. Disconnect all antennas/coax from the radio
  7. While watching the software RX meter, decrease the OS RX level from 100% until the software RX meter reads 30dB.
  8. Reconnect antennas/coax

TX Settings: (WSJT-X)

  1. In WSJTX, enable “Remember power settings” checkboxes for Tune and Transmit under the Audio tab in settings.
  2. For each band of operation, set the power output slider only high enough to trigger an automatic tuner if you are using a tuner when clicking the “Tune” button.
  3. For each band of operation adjust the power output slider while calling CQ so that the ALC does not engage.
    • Tip: start at ~50% and use the arrow keys to lower the slider.

Other Software: (FLDIGI, ETC.)

Follow the Fldigi guide.


The procedure may seem arbitrary but these settings produce a very reliable input and output with no overdrive/underdrive while maintaining close to maximum input/output without introducing unnecessary noise. I’ve received +28dB (S9+) with no receiver overload and regularly successfully decode stations at -24dB indicating excellent dynamic range. You’ll see that my procedure is essentially the same as the Fldigi guide with some tweaks specific to WSJT-X. Fldigi is unfortunate in that it doesn’t have internal audio output signal controls like WSJT-X. You’ll need to modify the OS audio device levels as prescribed for its modems.