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MFJ-1278B MULTI-MODE APPENDIX B MODEM CALIBRATION
7. Adjust R77 for 2200Hz +/- 2Hz. Press the SPACE BAR.
8. Adjust R105 for 2295Hz +/- 2Hz. Press the SPACE BAR.
9. Adjust R106 for 2125Hz +/- 2Hz. Press the SPACE BAR.
10. Adjust R122 for 2125Hz +/- 2Hz. Press the SPACE BAR.
NOTE: If recalibrating the VB modem for Low Tone RTTY, then remove the jumper from
JMP G, and adjust this control for 1275Hz. +/- 2Hz.
11. Adjust R119 for 2975Hz +/- 2Hz.
NOTE: If recalibrating the VB modem for Low Tone RTTY, then remove the jumper from
JMP H, and adjust this control for 1445Hz. +/- 2Hz.
12. Press the SPACE BAR, the MFJ-1278B will respond with:
Multilevel xmit...1900
13. Adjust R307 for a reading of 1900Hz. +/- 1Hz.
NOTE: For step 14 the frequency readings on the frequency counter should be compared to
the frequency readouts indicated by the MFJ-1278B. Note that the difference in the
two readings can be as much as 20Hz, this is normal.
14. With each press of the SPACE BAR, the MFJ-1278B will display the following
frequencies:
1550Hz.....+/- 20Hz.
1600Hz..... "
1650Hz..... "
1700Hz..... "
1750Hz..... "
1800Hz..... "
1850Hz..... "
1950Hz..... "
2000Hz..... "
2050Hz..... "
2100Hz..... "
2150Hz..... "
2200Hz
..... "