APPENDIX B 


    CALSET VALUES FOR VARIOUS MODULATOR TONE FREQUENCIES



               (1274/78)  (TNC-2)
Tone   CALSET #  Adjust    Adjust    Modem / Remarks


2120**   248      R106      R78      HF Packet & RTTY
                                     Fc = 2200 Hz
2320**   227      R105      R77      200 Hz shift



1600     329      R106      R78      HF Packet & RTTY
                                     Fc = 1700 Hz
1800     292      R105      R77      200 Hz shift



1300     404      R78       R78      Packet / Fc = 1700  Hz,  
                                     800  Hz  shift.   CCITT 
                                     V.23  std.,  preferable 
                                     for HF 1200 baud, works 
2100     250      R77       R77      well on VHF FM too


      
1200     438      R78       R78      Packet  / Old 1200 baud 
                                     standard.   Too wide to 
                                     fit comfortably through 
                                     SSB filters for  linear 
2200     239      R77       R77      mode 1200 baud use
      


2125     248      R122*     NONE     VHF RTTY
                                     Fc = 2550 Hz  
2975     177      R119*     NONE     850 Hz shift


750      701      R139*     NONE     CW

775      678      R139*     NONE     CW

800      657      R139*     NONE     CW

825      637      R139*     NONE     CW

850      618      R139*     NONE     CW / SSTV

1500     351      R138*     NONE     SSTV

2178     242      R122*     NONE     HF RTTY/ASCII/AMTOR 
                                     Fc = 2220 Hz 
2263     233      R119*     NONE     85 Hz shift. ***



* These adjustments available on MFJ-1278 only.


** This tone pair may require a change of resistor values on 
the  modulator  header  so  that the  tuning  range  of  the 
adjustment pots will cover the listed frequency.  (TNC-2)


*** Military standard for data rates below 110 baud.  Allows 
use  of very narrow IF filters for noise bandwidth reduction 
and  interference  rejection.   Requires R141  value  to  be 
changed  to  300  K ohms.  This will make  wide  shift  RTTY 
unavailable  on  the "normal" demodulator.   The  1200  baud 
packet  demodulator can be selected for wide shift RTTY  use 
by the OPMODE command.  

If you have a MFJ-1278 and HF RTTY / ASCII / AMTOR operation 
is  a primary consideration,  and baud rates beyond 110  are 
not  anticipated,  some  improvement in performance  can  be 
gained  by  changing the value of C64 to 0.033  microfarads. 
This is easily done by tacking a 0.022 microfarad cap across 
C64.