9600bd Modification for IC-251</H3> </head> <BODY TEXT="#FFFFFF" BGCOLOR="#000000" LINK="#FF0000" VLINK="#8000FF" ALINK="#FF0000"> <H3>9600bd Modification for IC-251</H3> <blockquote> Digital modulation applied to top of deviation pot at the junction of R58, R60 and R61 (just below Q13 on circuit diagram). Modulation voltage from standard G3RUH 1200 bps modem wasn't high enough but was boosted by component changes on the modem board. A higher voltage is required from the G3RUH 9600 bps modem; output level pot set to about four fifths of maximum and works well. <P> PTT connection made inside the rig to the appropriate pins on the rear panel's accessory socket - no complications here, my TNC's PTT comes from a reed relay. <P> No modifications done for digital output from receiver (yet). <P> Have investigated modifying to provide up/down control but checks are incomplete. Suspect provision of this facility is possible and have identified (display) DRIVER IC2 pins 3/11 as the likely place to apply it. <P> Once AO-21/Rudak starts with higher speeds I'll probably expedite the provision of receive output and up/down control. </blockquote> </body> </html>