MFJ-401B ECONO KEYER
The MFJ-401B econo-keyer provides iambic key operation and dot-and-dash memory to make
sending easier. Please read all instructions before attempting to operate the keyer.
INSTALLATION
The MFJ-401B is operated with either a battery or external power supply. A 9 V battery may be in-
stalled by loosening the two screws on the side of the casing and removing the cover. A battery
clip and a holder on the top of the cover are provided for installing a 9 V battery.
A 12 VDC, 300 mA power supply may also be used to power the MFJ-401B. A 2.1 mm coaxial plug
with a positive center and a negative sleeve should be used with this power supply. The MFJ-
1312B, an optional 12 VAC adapter is available from MFJ Enterprises, Inc.
Select either iambic or straight key operation.
Iambic key operation is enabled by connecting a squeeze key to the keyer using a standard 1/4-
inch stereo phone plug. This plug should have either two conductor-common shielded cables, or
two single-conductor shielded cables with the shields tied together and attached to the ground
wire. The dot wire should be attached to the ring of the plug, and the dash should be attached to
the tip. The shield should be connected to the ground wire.
Straight key operation also uses a standard 1/4-inch stereo phone plug (a mono plug will not
work with a straight key on the MFJ-401B). The straight key wire should connect to the tip of the
plug, but nothing should be connected to the ring of the plug.
Note: For straight key operation,
the Auto/Semi-Auto switch should be pushed in
.
Output keying circuit allows keying of gridblock and solid-state transmitter.
To key the gridblock, use the RCA jack with the "grid block" label. Connect a shielded cable from
the "keying output" of the MFJ-401B to the transmitter. The grid block output keys a maximum
negative voltage of 200 Volts to ground at 10 mA.
To key a solid state transmitter, use the output labeled "direct." Connect a shielded cable from
the "keying output" of the MFJ-401B to the transmitter. The direct output keys a maximum positive
voltage of 60 Volts to ground at a maximum current of 200 mA.
Note: Consult the transmitter's instruction manual to determine which output to use. When in
doubt, try both jacks. The transmitter will key continuously when the cable is connected to the
wrong jack.
OPERATION
After the unit is properly connected to the transmitter, the MFJ-401B is activated by using the red
"ON/OFF" switch. After the power is on, speed and volume controls may be adjusted to desired
levels.
The tone control is located internally and may be adjusted by inserting a small screwdriver into
the hole on the side of the casing. This hole is found toward the back of the keyer.
Note: When op-
erated with a transmitter that has a built-in side tone, the sidetone on the MFJ-401B may be
turned off to conserve power if using a battery.
