MFJ CW Gear — Vol 1: Introduction

1.1 About this volume

Two instruments share this volume — both MFJ Enterprises pocket-class CW training and sending gear. The MFJ-419 CW Elmer is a receive-side learning aid (random code groups, Farnsworth method, USB text mode); the MFJ-422D Electronic Keyer Paddle is a send-side iambic-keyer-plus-paddle combo that plugs into any HF rig’s key jack. Neither transmits, receives, or talks to a hotspot. They sit in the radio drawer until practice or operating time — the radios are the subjects; these two are the training and operating tools for CW.

The cross-links from this volume run to the radios these instruments support: Vol 9 (Xiegu X6100) for the HF rig the MFJ-422D drives; Vol 25 (closeout) for the laminate-ready bench-instrument quick-reference card.

The bench instruments that used to share this volume — the Gigatronics 6060A signal generator and the Radio City Products 665 VTVM — now live in the Test Equipment collection: Gigatronics 6060A and RCP 665 VTVM.

1.2 MFJ-419 CW Elmer (Morse code practice generator)

The MFJ-419 is a dedicated Morse-code training appliance — no transmitter, no receiver, no antenna, no radio in the loop. The whole point is to take the radio out of the practice loop and give the operator a focused environment for learning to receive, send, and analyze Morse code with neither the spectrum-management problems of going on-air to practice nor the embarrassment of fumbling code in front of other operators. It is the practice-room piano for CW.

1.2.1 What it is, and what it isn’t

The MFJ-419 is a pocket-sized desktop unit — roughly 5 × 3 × 1.5 inches — with a built-in 2 × 16-character LCD, an internal speaker, a headphone jack, a push-button internal key (“Internal Key – Press to key” in the manual), an external key jack for a separate straight key or paddle, and a Micro-USB-B connector that serves both as a power input and as a serial port. Power can come from a single 9 V alkaline battery (NEDA 1604A) or from any USB source (computer port, USB-C-to-USB-A power bank, mains adapter); when both are connected, USB takes precedence and the battery is disconnected.

What it isn’t: a transmitter (no RF anywhere in the box), a CW decoder for over-the-air signals (it doesn’t tune anything — it just plays code at you), or a substitute for the MFJ-422D (the 422D plugs into a real HF rig and sends real CW; the 419 only generates audio and decodes the internal key in software). The 419 and the 422D are complementary, not redundant. Inside, the 419 is an ATmega328P with an FTDI FT232RL USB interface that emulates an Arduino Nano, and its firmware is updatable from the Arduino IDE (manual V1A, 2024; see Vol 2).

1.3 MFJ-422D Electronic Keyer Paddle

The MFJ-422D is an iambic electronic keyer with a dual-paddle integrated — a microcontroller-based keyer driving its own pair of paddle contacts, all in one small enclosure. Where the MFJ-419 is the practice tool with no radio in the loop, the 422D is the operating tool with a radio in the loop: it plugs into an HF rig’s key input and lets the operator send real CW on the air.