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Reviews Categories | Antenna Tuners/Matching Networks | MFJ-939 automatic antenna tuner Help

Reviews Summary for MFJ-939 automatic antenna tuner
MFJ-939 automatic antenna tuner Reviews: 26 Average rating: 3.9/5 MSRP: $159.95
Description: Plug & Play! You won’t even know it’s there . . . MFJ-939I/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 . . . and it’s made in the USA.

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

AdaptiveSearch 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.

InstantRecall 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 VirtualAntenna Memory
MFJ exclusive VirtualAntenna 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/1000V relays, RF duty silver mica caps won’t burn up. Safe, reliable, continuous 200W SSB/CW.

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

Never Obsolete . . . Super Versatile
Truly Plug & Play! No settings, only one cable to plug in! Order MFJ-939I, Icom; MFJ-939K, Ken; MFJ-939Y, Yaesu. Specify Yaesu: FT-100/450/950/ 857/897/1000MP/9000/2000 or other.

Never Obsolete!

If you get a new transceiver, simply order a new Plug and Play cable.

Super Versatile! Works with ALL older rigs, classic transmitters, Flex, Elecraft, Tentec, QRP, others. Auto tune antenna -- touch tune button on any MFJ-939I/K/Y for any rig.

2-Year NoMatterWhatWarranty
Product is in production.
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KD5JZN Rating: 4/5 Nov 20, 2017 23:04 Send this review to a friend
Good for the price  Time owned: 6 to 12 months
I've run the MFJ939 with my TS2000 for about a year now. The tuner works just fine 90% of the time. It will match my OCF Windom within a second or two , with the rare occasion that an end of my antenna is touching the metal roof. Otherwise the tuner works flawlessly with either the TS2000 or the IC706MK2G{ once I reset the internal jumpers}.
Is it, or do I expect it to be perfect for the $150 price? Of course not, you do have to approach this hobby with a slice of common sense and realize that you get what you pay for. Overall. this tuner preforms well for the price...
WD8U Rating: 5/5 Jul 20, 2017 16:56 Send this review to a friend
MFJ great service  Time owned: 0 to 3 months
I got a new IC-7100 and wanted an automatic tuner for it. So I bought a mfj 939I..
Had some problems with it...but after a few emails
with there support (Richard) got another one to me Fast! It works great with the IC7100..
They stand behind there products and provided me with a Fast solution,, with out effort on my part.. I am very satisfied with there service and product,,,The MFJ-939I tunes fast and has a wide swr range.
K8DXX Rating: 5/5 Jun 28, 2017 12:59 Send this review to a friend
Provided Excellent Service During 5 Month Florida Vacation  Time owned: more than 12 months
This is a follow-up to my 2016 review. My MFJ 939I (Icom) has provided flawless service through two field Days and a 5 month Florida vacation. It just plugs into the radio. Press the TUNE button and it either goes into service and/or tunes the current load. Want to retune to get a better match? Press and hold the TUNE button for 2 seconds and it makes another attempt. In virtually all cases, it achieves a 1.3:1 or better match on each band/frequency I tried.

While in Florida, it successfully handled a DK9SQ portable wire loop from 40 - 10 meters. At best, the loop presents a 4.5:1 mismatch, worse on most bands. The only anomaly I noticed was under some circumstances, the green power light would flash on and off during transmissions. This may have had to do with being within 20 feet of the radiating antenna. Usually, retuning would make the harmless flashing light go away.

The durability of this tuner also seems good. While I carried my IC-7300 in after most operating sessions, I usually left the tuner and MFJ Mighty Lite ACPS out on the screen porch. Both undoubtedly took some wind blown rain and other abuse but suffered no functional or cosmetic effects.

For $150, you can't beat it with a stick. I continue to have good luck with a wide range of MFJ/Ameritron products. Hats of to Martin Jue and his crew!
K3JLS Rating: 2/5 Jun 27, 2017 08:15 Send this review to a friend
STILL Won't Work with FT-450D  Time owned: 0 to 3 months
I read the older reviews on this tuner that stated it wouldn't work seamlessly with the FT-450D. So, I called MFJ and they reassured me that a firmware fix had been applied to correct this problem. I ordered the tuner.

When it arrived, I connected it up per the instructions. While it would tune manually (sticky tune), I would not work when the FT-450's tune button was depressed.

I called MFJ and asked about the option jumpers to be installed within the case. This unit came factory fresh with just one jumper placed on the JP2 'Y' punching. This was right, per the on-line instructions. The instructions also called for a jumper on JP4, but there was no push on jumper there, if that indeed was the proper location, nor was a spare push on jumper provided.

The fellow with whom I spoke was not that helpful and offered to have someone call me back 'later'. I told him that I wasn't interested and that I would return the unit and leave a negative reply on eHam to which he replied 'OK'.

I told him it was hardly 'OK'.
K8YZK Rating: 4/5 Feb 7, 2017 02:31 Send this review to a friend
Surprised  Time owned: 0 to 3 months
Ok, I only gave it a 4 because no hard copy of the manual, it is online only, and it has some problems, like showing where the jumpers are. I ended up calling support and the guy I talked to wasn't sure and had to contact someone else.

Got this to use with my IC-746, which has a so-so tuner. I found that I could not tune parts of 40 meters or 80 at all, so I looked at this. After talking to a rep at Gigaparts, I decided to get one. They did not have the Icom available but had the Yaesu, (tuner comes setup and with a cable for your radio), so I had to purchase another cable, but now if I get another yaesu I am set for them.
I use a short end-fed (Maple Leaf) antenna, suppose to be good for 80-6 meters. The tuner has no problems finding a match for the freq's/band I work. Well the other night I said let's see what it does on 160, and it found a match even with this shorten antenna. Now how efficient it is, that is something different.

Overall I would recommend it, just wish the cables were a tad cheaper.
KD0USA Rating: 5/5 Jan 28, 2017 00:55 Send this review to a friend
Apply P T T your Done   Time owned: 0 to 3 months
M F J 939Y Connected it to my Yaesu 857D with
COAX JUMPERS and Y cat cable . Used LOW power and Tuned ALL the Bands i Talk on. Increased the power
and it worked that Quick. It was press the P T T on the mic and thats it . nEXT ON my Hy-Gain 3750
i do not have a port for Electronic Tune. I sent a email to MFJ Tech . is it possible to use the tuner on a 40 year Tune & Load Rig. Reply was YES
just put your coax in and out . I did that and Lowered the Power . Bingo DONE i bought a 2d MFJ939
that day.. KD0ZK
W2QID Rating: 5/5 Nov 15, 2016 07:53 Send this review to a friend
Impressive unit  Time owned: 0 to 3 months
I purchased the MFJ-939K to use with my various Tentec rigs and a vertical antenna. They are specifically designed for the imported transceivers but are also supposed to work with others without a supplied connecting cable. The bottom line is that it is well made and all the "IntelliTuner" features make it an awesome piece of equipment. The really negative aspect of this jump into the world of MFJ for me was the absence of any guidance in using the tuner without the connecting cable, as in the case of a Tentec. Once I removed the optioning suitcase plug everything came together. Before that it did not work properly and had a frustration level of 5 using the EHAM rating scale. Another oversight in the manual is the reference to a bias-T circuit that is actually not present.
HB9AMO Rating: 2/5 Oct 30, 2016 01:25 Send this review to a friend
Could be better  Time owned: 0 to 3 months
I have both the MFJ-939 automatic tuner and an old MFJ-971 portable manual tuner. I can achive better results with the manual tuner than with the automatic one. In many cases the MFJ-939 refuse to tune the antenna because of too high SWR but i can get a quite good results with the manual one.
K4DZQ Rating: 5/5 Sep 18, 2016 05:49 Send this review to a friend
Filled My Needs  Time owned: 3 to 6 months
Wanted a stand alone automatic tuner for my Flex 1500 with a 100 watt amplifier and my KX3 with a 50 watt Hardrock amplifier. Both rigs are connected to a Zero5 Vertical through the tuner. I band switch through the rigs and tune from the front panel of them also.
It is very convenient and has been problem free.
I feel that it has been a worthy purchase for me.
EA3FNI Rating: 5/5 Jul 31, 2016 22:09 Send this review to a friend
BUEN ACOPLADOR  Time owned: 0 to 3 months
Mi experiencia ha sido muy buena despues de usar un acoplador de antena manual. Lo estoy hacienso servir con un Yaesu FT 450 y funciona estupendamente, no he tenido los problemas descritos en otras opiniones. Lo unico que encuentro malo es que no hay traducción de su manual de usuario en español u otros idiomas.
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