Gain control...
 

At my old carrier, on the RADARs on the Bus, we didn't have a Gain Control. Nope... Instead, in the place of the gain knob, was another tilt knob. So, the First Officer and Captain, each, had his own tilt knob. You would get a picture update with every other sweep.

This was a nice feature, since you two could pick different ND ranges with different antenna tilts and get nice close-up and far-away shots of what you're dealing with.

Airbus has a beautiful Power Point presentation of how to use the RADAR (including when and how to use the Gain control...if installed). If you contact them, I'm sure they'd be happy to help.

Tom