karn@allegra.UUCP (Phil Karn) (01/22/84)
Relayed from TAPR: Anouncement, Announcement, . . . We've found a modification to the TAPR modem which will significantly improve performance under ALL conditons. The change is extremely easy to make, and involves one part change, and one small re-calibration. Part change on the Beta Board: change C25 from .01 to .0047 microfarads. Part change on kit board: Change C20 to .0047 (it's the same cap. as in Beta mod.) Finally, for both boards, change the 2211 center frequency from 1700 to 1635 by using the calibration routine for 1700Hz by entering the calibration routines, and typing: cal:3/1127 which will calibrate your normal 1700 freq. to 1635 Hz. This mod should really improve things ina big way, and we even think it will permit operation to 1800 baud! This mod is entirely due to the efforts of N7CL, who has been responsible for a number of suggestions in the past, all of which have improved our lot. (For those of you with an interest in why this mod works: the cap. change takes the 2211 from an underdampted condition to critical.) 73 Dan