Connect ground to pin 2 (COM) and the middle line to pin 4 (MKE).
Go to the MENU and on the right side of the screen push the LINEAR AMP button. Press MORE to rotate the menu options if the LINEAR AMP button is not present.
In the LINEAR AMP menu set:
Linear Amplifier to On
Internal Relay Control to On
Keying Logic to Active Low
Linear Amplifier to On
Internal Relay Control to On
Keying Logic to Active Low
Do this for HF and the 50 MHz band.