A controller for the RS3000 switcher. It makes sure that the switching can not be engaged while one of the users is transmitting.
PTT lines of both radios are connected with the PS3000 control box.
In case the user presses the Reverse button while the other user is transmitting the controller will hold until the PTT line is not active and will do the switching then. In this case the Wait LED will turn on.
This makes the switching safe no matter the transmit squence between the users.
The control box is powered with a 13-15VDC.