all

Bands

Frequency	n/a (CW electronic keyer)
Power	Keyer/accessory. Keys the transmitter through a solid-state or grid-block output; produces no RF.
Modes	CW (iambic keyer, modes A/B), CW (single-lever)

Connectors

paddle in	1/4 in stereo jack (rear)
key out	RCA phono; solid-state or grid-block via internal jumper
ext speaker	1/8 in mono
power	2.1 mm coax, 9 V battery or 13.8 VDC
power req	9 V battery for portable use, or 12-13.8 VDC via 2.1 mm jack

Microprocessor iambic keyer supporting single-lever and dual-lever paddles Dot/dash memory, self-completing elements and jam-proof spacing Front-panel speed, weight, sidetone frequency and volume controls Built-in speaker plus external speaker jack for sidetone monitoring Single message memory and selectable Type A / Type B keying RF-proof design, Tune switch, and solid-state or grid-block keying jumper for tube rigs

Strengths

Full-featured yet affordable; genuine iambic A/B with weight control; runs on a 9 V battery for field use; grid-block option keys vintage tube transmitters.

Weaknesses

Only one message memory; no keyboard/serial input; utilitarian black box aesthetics. MFJ ceased manufacturing in 2024, so confirm availability.

Verdict

A long-running, do-everything standalone keyer, the default choice when a rig lacks a good built-in keyer or you want front-panel weight and tune control.

The MFJ-407E is a microprocessor iambic keyer with front-panel speed, weight, tone and volume, a built-in speaker and a one-message memory. An internal jumper switches between solid-state keying for modern rigs and grid-block for tube transmitters, and it runs on a 9 V battery for portable CW.

Pair it with a paddle such as the CW Morse Pocket Double Paddle, or compare the self-contained Katsumi EK-160 keyer with its own built-in paddle.

MFJ-407E Deluxe Electronic Keyer