MFJ MFJ-415B User Manual

Table of Contents
General Description.........................................................................................................	1
Using the MFJ-415B .......................................................................................................	1
PC Board 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 Case of Difficulty........................................................................................................	5
Technical Assistance .......................................................................................................	5
Schematic ........................................................................................................................	6
Parts List..........................................................................................................................	7

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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.

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