MFJ-9420 Installation Manual
20-Meter SSB Travel Radio
STEP 6. To transmit, press the mic's PTT switch and speak at normal conversational level with the mic held about 2
inches from your mouth. The MFJ-9420 has a very potent speech processor and will pick up your voice at
full intensity. Avoid the natural temptation to yell or close talk this will only overload the processing
circuit and hurt the intelligibility of your signal!
SPECIAL OPERATING NOTES
The MFJ-9420 does not have automatic high VSWR shutdown and you must provide a "reasonable" 20-Meter
antenna to ensure proper operation. Whenever possible, use a low SWR resonant type antenna such as a dipole or
tuned vertical. If you use an ATU (or a high Q loop such as the MFJ-1786 or Isopole 10 30), carefully rough tune
first for maximum S-Meter readings before activating the CARRIER switch.
Under FCC Rules, licensed amateurs are solely responsible for the frequency of operation of their transmitters. MFJ
cannot be held responsible for out of band operation due to misinterpretation or miscalibration of the MFJ-9420
analog VFO dial.
SIMPLE 20-METER ANTENNA SUGGESTIONS
COAXIAL FED DIPOLES: A wire dipole for the phone band should measure about 32'10" (16'5" per leg). Feed
with RG-58U or RG-8X; raise high and in the clear for best performance. If you have only one high support, make
an inverted V. The "full sloper" (sloping dipole) is also an excellent single support antenna with some directivity.
>90
Best
Direction
Support
34’ 4”
DIPOLE
INVERTED V
FULL SLOPER
MFJ-1772 PORTABLE DIPOLE: As an alternative to making a coax-fed dipole, consider purchasing the pre
assembled MFJ-1772 antenna. This is a no compromise 20-Meter folded dipole complete with 30' of feedline all
made from ultra lightweight 300 Ohm twinlead. Connect a random length of coax from the MFJ-1772 feedline to
your rig and let the antenna's built in 50 Ohm matching network do the rest. The antenna is pre tuned, easy to
handle, and sufficiently broad banded to cover both the CW and phone band.
3.0
2.0
1.5
1.0
SWR
FREQ
14.0
14.1
14.2
14.3
Flat Top
End-line
Balanced
Feeder
50-Ohm
Coax
TYPICAL SWR CURVE
MFJ 1772 DIPOLE
WARNING: CONSTRUCTING OR ERECTING AMATEUR RADIO ANTENNAS IN LOCATIONS
WHERE THEY MAY COME INTO CONTACT WITH ELECTRICAL POWERLINES
MAY RESULT IN ACCIDENTAL INJURY OR DEATH!
