
MFJ-784B Instruction Manual
Advanced Features
Error! Main Document Only.
-4
CW Spotting Tone
To help you find the center frequency for the CW filter, the MFJ-784B is
equipped with a CW spotting tone. The spotting tone marks the center
frequency of the tunable CW filter but will not work in a memory CW filter.
While the spotting tone is present, the bandwidth of the CW filter is opened to
maximum allowing you to "zero in" on any CW signal from 300 Hz to 1000 Hz.
As the spotting tone pitch, adjusted with the
Tunable Filters
left knob, gets
close to matching the incoming CW signal's tone, you will hear a beat note.
This note will decrease in pitch until a very slow waver or fade is heard in the
signals. When this wavering is adjusted to the slowest rate, the center
frequency of the CW filter matches the incoming CW signal.
To use the CW spotting tone:
1.
Select the CW Filter. The
Filters
switch must be turned to CW and the
Memory
button must be out.
2.
Engage the filter by pressing and locking the
DSP
button in.
3.
Press and hold the
Program
button to activate the spotting tone.
4.
Use
the
Tunable Filters
left knob to zero-beat (match) the spotting tone
and the CW signal.
5.
Release
the
Program
button.
6.
Decrease the bandwidth with the
Tunable Filters
right knob to eliminate
all other signals.
Measuring Frequency
By using the spotting tone, you can measure the approximate frequency of any
audio tone between 300 Hz and 1000 Hz.
1.
Disengage
the
DSP
button out to bypass the filter.
2.
Select the CW Filter. The
Filters
switch must be turned to CW and the
Memory
button must be out.
3.
Engage the filter by pressing and locking the
DSP
button in.
4.
Press and hold the
Program
button to activate the spotting tone.
5.
Use
the
Tunable Filters
left knob to zero-beat (match) the spotting tone
and the signal you wish to measure.
6.
Release
the
Program
button.
7.
Release
the
DSP
button. Press and release the
Program
button.
8.
Copy the CW. The number following
CF
is the signal's approximate
frequency. (You are using Talk. See the Talk section on page 4-5.)
Summary of Contents for MFJ-784B
Page 5: ...MFJ 784B Instruction Manual v ...
Page 6: ......
Page 12: ...MFJ 784B Instruction Manual Introduction Error Main Document Only 4 Block Diagram ...
Page 18: ......
Page 25: ...MFJ 784B Instruction Manual Installation Error Main Document Only 7 ...
Page 26: ......
Page 40: ......
Page 73: ...MFJ 784B Instruction Manual Appendix A 9 NOTES ...
Page 74: ...MFJ 784B Instruction Manual Appendix A 10 NOTES ...