ICS Controller Modification of Control RX Input

Allow the Control RX audio to be passed onto the TX audio bus.
--for the ICS Linker, Linker II, and Basic Controllers--
By Brian Martens KA9PMM
of ICS Repeater Controllers

Concept- The ICS Linker, Linker II, and Basic controllers all have a Control Receiver audio and COS input. It is possible to modify any of these controllers to allow the audio being presented to the Control RX port to be passed onto the repeater transmitter output.

Advantages- The controller can be modified to allow audio from another source like a Weather Alert Radio to be retransmitted over the repeater without tying up a dedicated link port, or in the case of the Basic, it has no link port, but this mod will allow an additional audio path to exist.

Operation- Text to be added here.............

Modification- On the Linker and Linker II, by soldering a 10 K resistor from Pin 7 of U2 to Pin 2 of U5, will send non switched audio from the control RX amplifier output to the TX audio amp and you can then set the audio level with the CTRL RX audio pot.

On the Basic, you would need to add a 1 uF cap and a 10 K resistor. The cap goes to the wiper of R19 and then to the resistor. The other side of the resistor would get soldered to Pin 9 of U3C.