MFJ MFJ-415B Instruction Manual Download Page 3

MFJ-415B CW Adapter 

 

Instruction Manual 

MFJ-415B CW Adapter for MFJ HF-SSB Radios 

 
 

General Description 

Installing the MFJ-415B in your MFJ-9420 or MFJ-9440 Travel Radio provides the 
valuable option of being able to switch modes at the push of a button to enjoy world-wide 
CW contacts.  The MFJ-415B works with virtually any key or keyer outfitted with a 
3.5mm mini plug, and features adjustable semi-break-in keying, a built-in sidetone 
sounder, and adjustable frequency-offset.  Travel Radio CW power output is typically 6 to 
10 Watts. 
 

Using the MFJ-415B 

Be sure to read this manual thoroughly before installing and using your adapter.  
Installation requires a simple one-time alignment procedure to ensure VFO accuracy for 
your particular radio.  Step-by-step instructions are provided in this manual. 
 
Once installed, the adapter is activated by pressing the 

CW IN/OUT 

switch on the back 

panel of the transceiver.  When turned on, additional components are connected 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 must set this jumper for the model radio you are using. 
 
The MFJ-415B provides semi-QSK T/R switching.  QSK hold time is set to 
approximately 1/2 second at the factory, but may be reset to your preference by adjusting 
trimpot R102. 
 
The module's CW-offset feature provides an automatic 600-Hz frequency shift between 
transmit and receive.  This is  needed to generate an audible tone in the speaker of the 
receiving station.  The CW-offset trimpot--R103--is preset at the factory, but may be reset 
to personal preference.  Since Travel Radios do not have RIT controls, it is especially 
important to set CW offset correctly.  
 
To help you monitor sending, a 2.7 kHz sidetone sounder is built into the adapter.  
However, if your keyer already provides sidetone, you may disable the internal sounder 
by removing the shorting plug at header J104. 
 
The MFJ-415B is designed to be totally transparent during SSB operation.  When the 
module is turned off, the keying circuit is deactivated.   

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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