MFJ MFJ-415B, Instruction Manual, Page: 5 / 9

MFJ-415B CW Adapter Instruction Manual
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MFJ-9420: Set your VFO dial and signal source to 14.250 MHz.
MFJ-9440: Set your VFO dial and signal source to 7.200 MHz.
Find VFO coil L3--this should be visible through the access hole in the MFJ-415B
adapter.
Using an insulated tuning wand, carefully adjust L3 until the signal from your
calibrated signal source is roughly zero-beat in your receiver (exact zero-beat is not
necessary). When completed, the dial is now recalibrated in the SSB mode. If you
remove the CW module from your radio, you should recalibrate again to "undo" this VFO
correction.
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Module Calibration for CW Band (L101 or C103):
Before attempting to calibrate, confirm the shorting plug on J105 is in the correct position
for your radio. Next, set the VFO dial and signal source to the low-frequency edge of the
CW band:
MFJ-9420:
Signal source and VFO dial are set to 14.000 MHz.
MFJ-9440: Signal source and VFO dial are set to 7.000 MHz.
If your MFJ radio lacks a CW-band dial scale on its faceplate, set the VFO dial to the low
end of the phone band. The phone-band kHz markings will provide a rough guide to your
CW operating frequency.
To adjust the module, first press the adapter switch
IN
to activate the CW adapter. Relay
K101 should click on and you should be able to hear CW stations with an antenna
connected to your radio.
To calibrate the VFO dial, adjust the appropriate trim control on
the MFJ-415B module until the signal from your calibrated source is roughly zero-beat.
MFJ-9420: Use a small screwdriver to adjust C103.
MFJ-9440:
Use an insulated tuning wand to adjust L101.
When this adjustment is completed, your VFO will be now be calibrated accurately for
both SSB and CW operation.
Important Note: If you should ever wish to restore the factory-default settings to L101
and C103 for any reason, you may approximate them by adjusting as
shown below:
L101
C103
3-1/2 T
CCW
Mid-range
Setting