MFJ MFJ-415B, Instruction Manual, Page: 3 / 9

MFJ-415B CW Adapter Instruction Manual
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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.