MFJ-1270C/1274C MANUAL APPENDIX D: ALIGNMENT
Page 244
6. Measure this tone frequency with the counter. Record this value as
F(low).
7. Slowly and carefully tune the receiver so that the tone frequency is
increasing.
8. Find the point where the signal is reduced by 1 S-UNIT from the peak
value reached near the center of the filter passband.
9. Measure this tone frequency with the counter. Record this value as
F(high).
10. Calculate the required modem center frequency as:
Fc = [F(low)+F(high)]/2
Once the required center frequency has been determined, the modem calibration
can be carried out.
NOTE:
It is essential that the modulator tones be properly aligned FIRST as
they will be used to align the demodulator center frequency.
Set the modulator tones to Fc MINUS 100 Hz for the low tone and Fc PLUS
100 Hz for the high tone using the procedure given in the owners manual.
Align the demodulator to the modulator tones using the built in demodulator
alignment facility invoked with the RXCAL command described Appendix B
ofthismanual.
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