MFJ MFJ-415B, Instruction Manual, Page: 6 / 9

MFJ-415B CW Adapter Instruction Manual
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Module Adjustment for CW Offset (R103):
Offset is preset at the factory for roughly 600 Hz. However, if you prefer a different beat
note--or if stations consistently respond to your CQs off frequency--you should reset
R103.
To reset the offset, connect your MFJ radio to a dummy load and set it up to
"communicate" with a second transceiver. Begin by tuning in the CW signal generated
by the second radio to a comfortable pitch on your MFJ radio--as you would do when
tuning in a station calling CQ. Then, while sending a reply with the MFJ radio, adjust
R103 for a 600-Hz tone in the second radio's speaker. That way, you'll hear incoming
signals at the pitch you prefer--and your transmitted signal will sound on-frequency to
other stations listening for you. To approximate the factory-default adjustment for R103,
set the arrow pointer on the trimpot so that it points to the "R" in the "R103" silkscreen
marking on the pc board. Then, adjust from this starting point.
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Module Adjustment for QSK Hold (R102):
This establishes how long the TX relay holds in after you stop sending. QSK hold is set
to approximately 1/2-second at the factory--a typical delay for 13-20 WPM sending.
However, you may set this for 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 Note: Radio amateurs are solely responsible for knowing the
frequency they transmit on. If you work DX at the low edge of the band or if you are
restricted to a sub-band within the CW allocation, make sure you know where your band-
limits are. MFJ cannot be held responsible if your radio is miscalibrated or if you
accidentally transmit outside the prescribed frequency allocation for your class of license.
Important Tune-button Note: When powered on, the CW module's keying circuitry will
interact with--and disable--the radio's front-panel
Tune
button. If you need to generate a
continuous carrier in CW mode for ATU adjustments, use the key to activate a carrier.
The
Tune function will work normally when the CW adapter is turned off.
Important Microphone Note: If the push-to-talk switch in your microphone doesn't
disable the mic element during receive mode, you must unplug your mic before operating
CW. If you do not, stray voice signals and noise may be picked up and transmitted on
SSB along with the CW signal! The recommended MFJ-290 and Radio Shack 21-1172
microphones normally disable the mic line and may be left plugged in (so do many other
PTT type mics). However, if you are aren't sure of your mic's switching circuit, check!