Adding a discriminator output to a UBC9000XLT is rather straightforward. The scanner uses an MC3361 IC for narrowband FM. There is however no need to solder to this IC: the unfiltered audio signal can also be found at TP3

BC9000XLT

Follow the next steps to make the discriminator output:

• Install a 3.5 mm mono socket in the scanner's back
• Solder a piece of insulated wire to TP3
• Solder a 10 k resistor to the signal solder lug of the chassis socket
• Connect the wire with the other lead of the resistor

As the metal housing of the scanner is connected to ground, there is no need to have a ground connection to the socket.

Chassis socket and 10 k resistor in the scanner's back