4200 xl pressure dial/4th servo
 

I just noticed my replacement radio had the last aux channel for 4th valve
on the gear switch instead of Pit trim dial. By putting it on the pit trim; you can turn off the mix toggle and use the dial to manually adjust pressure from the radio as an option.

Re: 4200 xl pressure dial/4th servo
 

One note: You have to set the end point at 100/100 to allow the dial
to dial the servo back and forth.

Re: 4200 xl pressure dial/4th servo
 

Fyi..I run it with mix on and off (flip switch) and while the mix does
reduce pressure when not moving pistons..I found manual dialing up
the pressure allows more precision in operating/allows to adjust
overall operating speed/power and the sound card also scales up evenly with
the dial and not rev up and down during digging.