MFJ MFJ-415B Instruction Manual Download Page 5

MFJ-415B CW Adapter 

 

Instruction Manual 

 

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

 

 

Summary of Contents for MFJ-415B

Page 1: ...d Installation 2 Shorting Plugs 2 Adjustment and Calibration 2 Transceiver Recalibration of VFO 2 Module Calibration for CW Band 3 Module Adjustment for CW Offset 4 Module Adjustment for QSK Hold 4 In...

Page 2: ......

Page 3: ...to the transceiver s VFO circuit to shift frequency coverage into the CW portion of the band The specific components required to make the VFO shift are selected by the jumper plug on header J105 You...

Page 4: ...no sidetone remove it For MFJ 9440 place a shorting plug on center and rear pins of J105 For MFJ 9420 place a shorting plug on center and front pins of J105 Adjustment and Calibration Your MFJ 415B C...

Page 5: ...O 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 Th...

Page 6: ...personal preference by adjusting trimpot R102 To approximate the factory default position set the arrow on the trimpot to the 2 in the R102 silkscreen marking on the pc board Important VFO setting Not...

Page 7: ...e at least 40 dBc or 40 dB down from full CW output Technical Assistance If you have any problem with this unit first check the appropriate section of this manual If the manual does not reference your...

Page 8: ...MFJ 415B CW Adapter Instruction Manual 6 Schematic...

Page 9: ...5 Jack Stereo PCB 3 5 mm J104 612 0102 Header Pin Straight 375 1 2 Position J105 612 0103 Header Pin Straight 375 1 3 Position K101 408 1011 Relay Reed Type 12 V SPST L101 402 2710 Inductor Coilcraft...

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