PLEASE READ THIS ENTIRE MANUAL BEFORE OPERATING THIS EQUIPMENT!
The MFJ-486 Grandmaster Keyer is a state of the art microprocessor controlled iambic memory
keyer. This keyer has been engineered to combine sophistication with ease of use and should pro-
vide many years of trouble-free service.
This manual contains the instructions for the operation of the various features in the 486 as well as
an on-line sample edit session to make learning the advanced memory and edit functions as easy
as possible.
INSTALLATION
1. The MFJ-486 requires 12–15 VDC for operation. A 2.5 mm subminiature plug is needed. Wire
the plug so that the tip is positive and the sleeve is ground. AC adapter (MFJ-1312) is optional.
First plug the adapter into the subminiature jack on the rear panel, marked POWER, and then
plug the adapter into the 110 VAC wall socket. It is not necessary to unplug the adapter when
the keyer is not in use.
2. A squeeze key should be used. This will allow IAMBIC operation. Use a standard quarter inch
stereo phone plug and a two conductor shielded cable or two separately shielded cables. Tie
the shields together and use it for ground. The dot wire should connect to the ring of the plug,
the dash wire to the tip, and the shield to the ground.
3. A reliable solid state keying circuit allows keying of all grid blocks, cathode, and solid state
transmitters. For grid block keying use the "Grid Block" keying output. For cathode keyed and
solid state transmitters, use the "Direct" keying output. Try both outputs if you are uncertain as
to which output to use. The keyer outputs are self protected. The "Grid Block" output keys a
maximum negative voltage of 300 volts to ground at 10 ma. The "Direct" output keys a maxi-
mum positive voltage of 300 volts to ground at a maximum current of 100 ma. Use a shielded
cable to connect between the memory keyer and the transmitter key input.
4. If private listening is desired the headphone jack may be used. The headphone jack requires a
standard 3.5 mm mono plug with the sleeve being ground and the tip being positive. The inter-
nal speaker is automatically disabled upon insertion of a plug into the headphone jack.
5. A socket is provided for the connection of an external control. This remote control will control
the memory location and the edit functions that are also controlled by the smaller red pushbut-
ton switches on the face of the keyer. This remote control is the MFJ-77 and is available from
MFJ Enterprises Inc.
6. A coin type lithium battery is provided for power-off memory retention. After a period of time,
this battery may become exhausted. The battery may be removed by removing the top cover
(remove the two screws at the top back corners of the unit and slide the top rearward) and us-
ing a screw driver to remove the battery. The battery should be replaced by a BR-2325 coin
type lithium battery.
