MFJ-939Y4 Automatic Tuner


MFJ’s faster speed comes from advanced technology and software algorithms not from fewer solutions.


MFJ-939 I / K / Y automatically tunes your antenna as you tune your radio. SWR is just always low.

Tunes your coax fed or random wire antennas 1.8 – 30 MHz from 2 Watts QRP to full 200 Watts SSB / CW.

Matches 6 – 1600 Ohms (SWR up to 32 : 1) – that’s a 50% wider matching range than competing products that are less capable and higher priced.

Highly intelligent, ultra-fast tuning

As you’re ragchewing, contesting or DXing, the MFJ-939 is learning your antenna and the way you operate and storing all this in its 20,000 memories. The more you use it, the more it learns.

Measure and compute

MFJ-939 uniquely measures your antenna’s complex impedance (R, X), computes the L-network and snaps in needed components for instant matching.

Adaptive search

Adaptive search determines a sub-set of all solutions that can provide a safe match and searches only that subset giving you an ultra-fast match. Others search slowly through all solutions.

Instant recall

Instant recall first checks its memory to see if you have operated this frequency before. If so, tuning is instantaneous and you’re ready to go!

MFJ virtual antenna memory

MFJ exclusive virtual antenna memory system gives you 8 antenna memory banks of 2500 memories each.
You can use an antenna switch to select up to 8 antennas and assign each antenna its own 2500 memories.

4 times more solutions and faster

MFJ has 256 values each of capacitance and inductance for 131,072 matching solutions giving you a finely tuned very low SWR.
That`s 4 times the 32,768 solutions of competitors using only 128 L / C values each.

Don’t be fooled by competing products claiming fast search times – if you have a quarter of the matching solutions, of course, it takes less time to finish but it’s not faster.

MFJ’s faster speed comes from advanced technology and software algorithms not from fewer solutions.

Audio SWR meter

An Audio SWR meter beeps when SWR < 1.5, 2, 2.5, 3.
Alarms if > 3, audible & visible diagnostic messages.

Heavy-duty components
Heavy-Duty L-Network: 10 Amp / 1000 V relays, RF duty silver mica caps won’t burn up. Safe, reliable, continuous 200 W SSB / CW.

As small as your radio
Tiny 6 1/2 W x 2 7/8 H x 8 3/8 D”. 2.4 lbs. SO-39s, random wire ant. & gnd posts.

No settings, only one cable to plugin, order MFJ-939I, Icom; MFJ-939K, Ken; MFJ-939Y, Yaesu.
Specify Yaesu: FT-100 / 450 / 950 / 857 / 897 /1 000 MP / 9000 / 2000 or other.

Super-versatile works with ALL older rigs, classic transmitters, Flex, Elecraft, Tentec, QRP, others. Autotune antenna – touch tune button on any MFJ-939 I / K / Y for any rig.

2-year no matter what warranty.