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Reviews For: MFJ-939 automatic antenna tuner

Category: Antenna Tuners/Matching Networks

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Review Summary For : MFJ-939 automatic antenna tuner
Reviews: 41MSRP: 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
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
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
More Info: http://www.mfjenterprises.com/Product.php?productid=MFJ-939Y
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
00414.2
K8YZK Rating: 2017-02-07
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: 2017-01-28
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: 2016-11-15
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: 2016-10-30
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: 2016-09-18
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: 2016-07-31
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.
K0BEL Rating: 2016-05-24
Excellent job with IC718 and IC7200 Time Owned: 0 to 3 months.
For the price I didn't expect a lot with this tuner. But, I connected it, pressed the tuner button on my radio, the tuner would click and flash, and my swr was then fine. I used a manual tuner before this that was sometimes a pita. I would buy this again.
VE3XDB Rating: 2016-05-18
Didn't work at all. Time Owned: 0 to 3 months.
Received the package at noon yesterday. By 3:00pm it was in the mail, on the way back to DX Engineering. Here is an excerpt from the text of the email message that I sent to DX Engineering with the returned package.

"I purchased a MFJ-939K from you on May 10, 2016 and received it today. It did not work, right out of the box. Here is the sequence of events:

1. I wanted to use this tuner to tune my 40 meter quarter wave inverted L, which is resonant on 40 meters. The internal tuner on my Kenwood TS-440S/AT tunes this antenna on 40 and 15 meters, without difficulty. My primary objective with this purchase was to have it tune this antenna for 15 meters, with other rigs that don't have an internal tuner.

2. The tuner seemed to work on 40 meters, although it is so close to resonance that it may have just detected that and didn't try to tune.

3. On any other band, including 15 meters, it went into a cycle of click beep red light green light and wouldn't tune or stop.

4. I reset the tuner to factory defaults, cleared the memory and did a self test. The self test indicated pass, although the tuner clearly was not working.

5. I called Stan at MFJ and he had no solution for me, except to suggest that I add 8 feet of wire to my antenna. I did this, and as a result the tuner did not tune anywhere. So I believe the fact that it seemed to work on 40 meters was just because the antenna was already resonant."

DX Engineering was easy to deal with, but the MFJ product was very disappointing. Unfortunate, because I really wanted this to work. Had it worked, I was going to set it up for remote operation at the base of my antenna, and extend the antenna to a random length that would have worked on all bands.

I had previously been using an SG-237 at the feed point, and it worked well for about 8 years. Recently, it lost its little mind (or at least its memory) and thought it was time for something new. Now, I may open up the 237 to see if I can revive it.

Have a great day!
KD2JVX Rating: 2016-04-07
works great with the ic-7100 Time Owned: 0 to 3 months.
I was able to tune up a random wire and work 17m and 20m with no effort and get 1.5 SWR. Signal report from Italy was only 3 but i attribute that to the ground.
NH6RF Rating: 2016-04-02
Works fine for me Time Owned: 3 to 6 months.
Ordered direct from MFJ. Took awhile to get it because they were back ordered. Set up is simple and it worked as described. I'm using with a Yaesu FT-840 into a 67 foot Off Center Fed Dipole. Although antenna is designed for 40 meters and up, I've made many long distant contacts on 80 meters. I have the MFJ-874 SWR/Power meter installed. Like the Tuners manual says, 1 beep from the tuner after tuning is complete indicates an SWR of 1.5:1 or less. That's what I'm seeing. For me this tuner is working great.