The User Guide for WSJT-X says It is usually best to turn AGC off or reduce the RF gain control to minimize AGC action, but the Icom IC-705 seems not to have an option to turn AGC off, only to set it to fast, medium and slow. Should it be set to slow?
Actually you can get AGC off on the 705. The process is a bit roundabout, but it's the same as the other Icom touchscreen radios.
- Set the mode you're interested in (i.e. USB-D for FT8) because AGC settings are remembered per mode.
- Open the FUNCTION quick menu.
- Press and hold AGC for one second to open the AGC settings menu.
- Press whichever one of the AGC settings you want to be replaced by OFF.
- Turn the main dial all the way left — the setting below the lowest AGC time constant should be OFF.
- Press EXIT.
- Now you can select AGC OFF at any time.
FT8 isn't really that sensitive to AGC, though; you'll do very little harm by just leaving the AGC at MED.