MFJ MFJ-403, MFJ-403P User Manual

MFJ-403 Owner's Manual Pocket C W Keyer

Introduction

Welcome to the world of effortless CW. With the MFJ-403 you will have a professional sounding fist in no time! Whether you are a Novice or seasoned Extra, the MFJ-403 Pocket CW K eyer has the features you have been waiting fo r! Novices will appreciate the preset power-up defaults for plug-and-play operation. Extras will enjoy the advanced features: Weight control from 25 to 75%, Iambic A and B operation, automatic or semi-automatic operation, full dot and dash memories, and immediate front-panel speed control from 5 to 60 WPM (words per minute). The built-in sideto ne gener ator and spea ker are ideal for CW practice sessions or for radios lacking a CW sidetone.

The MFJ-403 keyer is compatible with any modern transceiver or QRP transmitter using positive keying. The 50-volt at 100-mA keying permits the use of many early vintage cathode-keyed transmitters. Its small size and battery oper at io n ar e i dea l f or QR P or Fi el d D ay ac ti viti es! CW has never been so enjoyab l e or ef fortle s s !

A s tate-of-the-art

PIC12C671 microprocessor is the heart of the keyer! Learn the basics behind embedded controllers, and how they are revolutionizing the electronics field. The powerful PIC device permits advanced settings to be entered from the keyer paddles, using Morse characters! Powered by a common 9-volt transistor radio battery, the keyer is ready for action wherever you are! The microprocessor even senses inactivity. Leave it sitting and the keyer goes into a battery conserving sleep mode!

Operatinq Instructions

Dits, daps, dots and dashes? Beginners often think of CW characters as being composed of strings of dots and dashes, the visual image conveyed when viewing Morse CW characters on the printed page. Experienced CW operators tend to think of CW characters as

a sound,

and hear

dahs

instead of dashes, and

dits

instead of dots when listening to CW characters. Both terms will be used interchangeably in the following text.

Determining Keyer speed: Hold the dash lever and count the number of dashes

generated in a five-second period. The number of dash es roug hly eq uals yo ur CW sending speed.

Power requirements:

The keyer is designed to operate from a 9-volt DC battery source. An alkaline battery will give long serv ice, but always remember to turn the keyer power switch off when the keyer is not being used.

Keyer paddles:

Most popular paddles will work well with the MFJ-403. Full

enjoyment of the MFJ-403 's features requires paddles that are capable of

MFJ-403 Owner's Manual Pocket CW Keyer

iambic operation. We recommend the MFJ iambic paddles as being a good value. Iambic paddles can be recognized by the totally independent operation of the

Dit

(or "Dot") and Dah (or "Da s h ") paddles. Some CW operators refer to ia mbic p add les as "squeeze paddles ".

The paddles should be equipped with a three-wire interconnecting cable terminated in a

Tip

Canmon

3.5mm stereo jack. Miniature shielded and balanced microphone cable is ideal for this. The

common return is connected to the longest "ring" (shaft)

of the stereo jack. The Dah paddle

R6q MA)

3.5mm amen Ject Repr to Ne mnneaor ped*n` for widnq tumind dads.

connection is made to the jack terminal for the smaller insulated ring. The Dit paddle is connected to the jack tip connection. If your paddles are equipped with a '/," stereo jack, a suitable stere o adapter is available at most electronic or HI-FI shops. Reversed paddle wiring can be corrected by a function entry, more on this later. Th e paddles arc connected to the Paddle jack on the MFJ-403.

Linear controls: There are two linear controls. A Volume control, accessed from the bottom of the unit, sets the sidetone monitoring level. Use a small flat-head screwdriver and rotate right to decrease volume. The second control, OFF/Speed knob, sets the CW speed over a range of 5 to 60 WPM. Speed is one of the most frequently adjusted parts of your keyer.

Sidetone operation: The sidetone is the tone keyed by the CW keyer. This per mits yo u t o monitor your keying and provides the aural "feedback" to assist in sending good CW. Many transceivers already provide for internal CW sidetone monitoring. If your transmitter does not have built-in sidetone monitoring provisions, the MFJ-403 will generate a sidetone for you. A builtin speaker lets you monitor the CW sidetone. Adjust the Volume control to a comfortable listening level.

Default initial status: As soon as power is supplied and the MFJ-403 is turned on, the unit is ready for operation. A microprocessor program "subroutine" loads several op er a t i ng p ar a me t ers into the keyer at po wer up. T he s e para me ters a r e based on standard operating practi ce s ; many of them may be

MFJ-403 Owner's Manual Pocket CIV Keyer

changed to suit your preferences-more on this later. Commands entered via the Function switch are cle are d when the power is removed.

Initially, the keyer assumes standard paddle wiring. This means the dit key connects to the tip and dah key connects to the ring of the 3.5 nom jack. Iambic operation is set to mode A. The sidetone frequency is set to 727 Hz. The CW weight is set to 50%, yielding the standard 1:3 dit to dah ratio. The keyer is in the automatic mode.

If CW operation is a new experience for you, consider runni ng the keyer in i ts basic power-up configuration until you become comfortable with its feel and operation. Feel fr ee to learn the more a dvan ced f eatu res at your own pace.

Default settings at power on:

1. Automatic

2. Iambic A

3. Standard paddle wiring (tip = dot, ring = dash) 4. 727 Hz sidet on e

5. Standard weight (50%, dot-dash-space ratio of 1:3:1)

Transmitter keying: The keyer output is through the Key Out jack, (RCA phono jack). You will need a cable connecting the keyer and the CW keying jack of your radio. The operation instructions for your set should show what sort of connector you need and its location on your radio. Many modern tra nsce ive rs use RC A pho no ja cks for connecting accessories. In those cases, ready-made cables for home entertainment devices may be used b etween the MFJ-403 and radio.

Keyer output specs: The keyer is designed for positive keying output. Most modern solid-state transceivers and QRP transmitters meet this requirement. Always c heck the owner's manual befor e attaching the ke yer to a radio. T he MFJ-403 will key positive voltages to a 50 Vdc maximum and current to a 100 mA maximum. Exceeding these limits may damage the keying transistor Ql.

Use with vintage sets: Early tube transmitters and hybrid transceivers may not be compatible with the MFJ-403. If the transmitter uses grid-block keying (a negative key voltage), it cannot be used with the MFJ-403. An ex ample of a grid-block keyed transmitter is the Heathkit DX60. Ch eck the ARRL handbooks for circuits designed to adapt keyers to grid-block keying.

Vintage novice transmitters commonly used cathode keying, a combination of high current and high voltage. The Heathkit DX40 used cathode keying, for example. In genera l, mo st catho de -keye d tran smi tter s are co mpat ible with the MFJ -403 keying circuit, so long as the 50 Vd c and 100 mA limits are not exceeded.

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