Kenwood recommends the PC-1 Phone Patch for all of our radios. Most other phone patches will work satisfactorily without any modification to the radio, requiring only an external speaker connection, and that the Mic line be run through the patch.
For those operators who desire a Patch input similar to the TS-520S or TS-820S, an input connection and terminal must be added at the Mic input preamp circuit.
Use a 100Kohm in series, with a 10Kohm to ground on the input side of the 100Kohm resistor. Use shielded line, and connect as follows:
On the IF Gen unit X49-1110-01 install the fixed divider at the junction of R43 10K, C42 100pF, & C43 1uF (input of Q18). Add an RCA jack, or use remote pins 7 and ground for input.
On the IF Gen unit X48-1240-00 install the fixed divider at the junction of R167 10K, C128 .001uF, & C129 1uF (input of Q32). Add an RCA jack, or use remote pins 7 and ground for input.