A few questions related to the KGX 150 :
There are a few things to be aware of with all UAT installations. These units require a control device and a switch to place them in air/ground mode. The switch is not a major issue and is a minor cost. However, the controller is additional if the aircraft is not already equipped with a transponder and/or display (MX20 for example).
As you’ll see below, yes, the KT-76C will pair with the unit via the antennas. Basically the UAT will sense the XPDR. This will enable you to send the Mode A and IDENT information to the UAT unit. However, you are still required per the FAA to have a way to know your ADS-B status. If a suitable display such as the Garmin MX20, Aspen EFD1000 or the KSN 770 is not installed, then a remote control unit is required. The KGX Control Panel list price is currently $619. Depending on the aircraft and the kind of flying, there are a lot of factors and options to consider.