TM321A.2 THE FOLLOWING IS AN EASY MOD TO SQUELCH THE AUDIO AT MIC PIN 6 FOR TNC'S WITHOUT TRUE DCD: OBTAIN FROM KENWOOD A 2SD1757(K) (SURFACE MOUNT TRANSISTOR). INSTALL EMITTER TO MIC PIN 8, COLLECTOR TO MIC PIN 6, AND JUMPER FROM BASE TO THE UNUSED PIN ON CONNECTOR 202. USING THE UNUSED PIN RATHER THAN RUNNING THE JUMPER TO THE MOTHER BOARD PRESERVES THE PLUG IN FEATURE OF THE FRONT PANEL. CONNECT ONE END OF A 4.7 K RESISTOR (I USED A 6.8 K) TO THE MUTE LINE (IC 5 PIN 7), AND CONNECT THE OTHER END TO THE UNUSED PIN OF CONNECTOR 4, WHICH MATES WITH CONNECTOR 202. THIS NEW CIRCUIT IS A CLOSE COPY OF THE AF MUTE CIRCUIT THAT SQUELCHES THE RX AUDIO AT THE SPEAKER. IT WORKS PERFECT WITH MY PACCOMM MICROPOWER 2. THE HARDEST PART OF THE MOD IS REMOVING THE LOCKING RING AROUND THE MIC CONNECTOR. I USED A MODIFIED TABLE FORK! GOOD LUCK.