PK232.22 THIS APPROACH REQUIRES REMOVAL OF Q6 AND REPLACING IT WITH THE PNP AND ADDING A "PULLUP" RESISTOR 47K FROM +5V TO THE INPUT SIDE OF R150 THIS CAN BE DONE ON THE CKT BOARD SINCE R149 HAS 5V ON THE END NEAREST THE FRONT PANEL AND THE PULLUP SHOULD BE ATTACHED THERE AND TO THE END OPPOSITE THE FRONT PANEL ON R150. IF YOUR PK-232 IS SOU PREFER NOT TO MODIFY IT YOU CAN INSTALL A CKT EXTERNAL BY ADDING A 2N2222 TRANSISTOR AND 3 RESISTORS HERE IS THE CKT : PK232 PIN 3 <--- -----------------------------> +5V # 5K RES. # 47K RES -----\ C \ 47K RES 2N2222 -----#------------------->----> TO KEY LINE E / B IN 914 / ---- GROUND THE ABOVE CKT CAN ALSO BE ADDED INSIDE THE PK-232 AND USE THE AVAIL +5V SUPPLY . THE ABOVE CKT IS THE ONE I'M PRESENTLY USING AS IT PROVIDES EXCELLENT ISOLATION FROM THE RTU'S TO THE PK232. I INSTALLED THE CKT INSIDE THE 232 ON TOP OF TAddress any queries to JIM/W5IFP @ W5IFP