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Reviews Categories | Antenna Tuners | MFJ-998RT Remote Auto Tuner, 1.5 kW, 1.8-30 MHz Help

Reviews Summary for MFJ-998RT Remote Auto Tuner, 1.5 kW, 1.8-30 MHz
MFJ-998RT Remote Auto Tuner, 1.5 kW, 1.8-30 MHz Reviews: 34 Average rating: 3.1/5 MSRP: $769.95
Description: An MFJ HF tuner (160 M-10 M), capable of 1.5 kW of power SSB and CW. It is an external tuner and can be installed at the base of the antenna, which yields better results than with the tuner in the shack. It goes well with the Ameritron amps: ALS-1300, AL-80B, AL-82, AL-1200 and AL-1500 legal limit amplifiers. It weighs 9.5 lbs and has an ABS plastic cabinet and stainless steel metal chassis. It measures 13.75x6.75x17.5". Matches instantly impedances from 12-1600 ohms and includes 20,000 virtual antenna memories. Has one coaxial antenna and a binding post for end-fed long-wire antennas. Upgrade firmware via a serial port. Includes a one year warranty.
Product is in production.
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You can write your own review of the MFJ-998RT Remote Auto Tuner, 1.5 kW, 1.8-30 MHz.

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N3PS Rating: 4/5 Jun 13, 2017 07:06 Send this review to a friend
Overall Happy . . .  Time owned: 3 to 6 months
I have not been a fan of MFJ (previously a DOA antenna analyzer and a stray nut found rolling around the inside an Ameritron amp) but needed a remote ATU solution for my 135' end fed antenna used for 80m and 160m. Currently, the 998RT is the only product capable of handling the full legal limit.

Overall, the unit has worked as advertised.

My only complaints:

* The unit requires a minimum of 20 watts to recognize transmit frequencies on 160m (10 watts sufficient on all other bands).

* When mounted vertically, and to keep the internal display right side up, the cover is upside down.

* The unit lacks range to tune up low impendence situations (< 50 ohms). In order to get the ATU to tune up my end fed on 160m, I eventually had to place a 1/4 wave matching section of coax between it and the antenna.
WD4ED Rating: 2/5 Jun 2, 2017 10:25 Send this review to a friend
Basically works but...  Time owned: more than 12 months
This remote tuner worked decently for about 6 months then stopped tuning. Sent it back for warranty repair. After about 3 or 4 months it was returned after some relays were replaced. It never worked quite as well as when it was new. Maybe they missed a bad relay or two during repairs. I can tell that even when it works, it can be finicky. I required almost constant power cycling and power level adjustment in order to properly find a tune. Depending on your antenna and feedline combination it has started retuning at odd and dangerous times. Like when running high power into it. If it does this, it will smoke the tuner in a large way. It is also easily destroyed by a single operator failure. This repaired unit is now dead with many burnt components. I was using it on 160m and accidentally transmitted about 600 watts into thinking that the tuner had successfully tuned. It hadn't. That's all it takes to kill one of these devices. IMHO, this is a serious weakness of relay, switched component based auto-couplers. A remote version of an HF-Auto is probably much more likely to survive these events. Several attempts to contact MFJ about a "paid" repair have gone unanswered. I'm guessing that there are enough of these things waiting for warranty repair that they aren't really interested in getting paid to repair them. Which means it's an expensive, consumable device that is easily damaged. Probably not the best investment. If you own or buy one. Be careful!
KN2M Rating: 2/5 Mar 26, 2017 18:46 Send this review to a friend
Second one, typical questionable MFJ quality  Time owned: 0 to 3 months
I have purchased two 998RT tuners, including a new one in the last week. The first one worked reliably for over 3 years on my 160m antenna, until there was a very very close lightning strike in the backyard. The box was sent back to MFJ for "repair". Months and months went by. I knew they had it, but never heard anything from them. Finally, about 6 months later I received a call from the service department indicating an unusual difficult to find problem had been found (intermittent) and they were ready to return the tuner. Finally! It has worked perfectly back in the same antenna since returned to me in October.

Now, on to the second recent purchase. I wanted to expand the useful VSWR on an 80m antenna. I ordered it from an Ohio dealer. It came USPS many days later than it should have. I now wonder if this delay or shipping choice had something to do with the subsequent problems which I will now describe. What an experience!

Being familiar with the tuner, it was no real problem installing it and the MFJ-4117 BiasTee Power Injector. I need to add that I did NOT put it on the bench and test it or set the matching VSWR to 1.0:1 as my other unit. I tuned to a portion of the phone band, the antenna tuned once and that was it. I opened up the case outside while connected to the antenna and the LCD display had all segments on but the tuner was obviously not functioning. Not only would the unit fail to respond to tuning, but it eventually went into a state that shorted the antenna, ie I heard NOTHING from it. I was duly frustrated, brought it inside on my bench and discovered that it seemed to operate perfectly well. This display was restored to normal. All I did was change to a different power supply, so I thought. I set the minimum VSWR to 1.0:1, went through the menu, tested it with a dummy load and put it on my antenna. I saw no problem whatsoever. I put it back on the antenna. The WX was cold with lots of snow on the ground by the way. This was one of multiple trips with the thing. Reconnected, the tuner failed to work at all. This time, at least I could hear signals and there was no short to ground. I wondered about my power supply. Could this be the problem? I changed it to the one that worked inside the house. It tuned the antenna once, then total failure again. I changed the wiring to the BiasTee connector. I thought perhaps the current or voltage stability of the new second unit was more sensitive than the older one. That made no difference. I noted curiously though the BiasTee was OFF when I went to troubleshoot the antenna that time. I could have sworn I had left it ON. Description, the BiasTee is located outside the station in a 12x12 plastic electrical box housing a coax switch, the other BiasTee for the 160m antenna, some other relays and listening antenna switches. The box was dry, connections taped. Huh? I turned it back on. Still no tuning. I brought the 998RT back inside a second time. It still worked properly on the bench. WTF? This time I took it outside into the cold and snow with my portable QRP rig, right at the end of the feed line going to the antenna. It worked! I reconnected everything, buttoned up the housing box and left it for the next day.

What happened? You guessed it, NO tuning. I went out again, back into the cold (about 25F that day) opened up my electrical box and again found the BiasTee OFF. I could have sworn I left it ON, why would I turn it off? I needed it off anyway because this time I took a separate 12 supply, the one that I had connected to the original 998RT for over 3 years, plugged it in with a long extension cord to power the 998RT directly. Guess what? Within seconds of plugging in the supply, it circuit breaker popped. I did this again and again. There was now a short? How could this be? Was the BiasTee acting like a circuit breaker and protecting the supply from a short condition and turning itself off all along?

I hauled the 998RT back to the bench a third time. I was now pretty convinced this was going to go back to the factory for another lengthy repair. But, I also figured what did I have to lose by troubleshooting it myself? How can I break something that was already screwing me every way to Sunday.

I connected the tuner to the power supply and each position I used, the outside connector, the inside connector and clip leads to the RF input all were short to the supply and tripped the circuit breaker. I removed the aluminum RF shield and its many screws in order to look around. I was searching for a bad diode or charred trace by one of the components. I saw nothing. I put power back to the unit with the RF shield off and it worked just fine. OK, either I just did something or this is really intermittent. I put the shield back on. It was noted at that time, the fit was poor. I really had to struggle to get all the holes lined up. I redrilled several. Power ON and no issue. I banged on the 998 a few times (we used to call this a maintenance wrap when I was in broadcasting) and it shorted out the power supply. I put pressure here and there on the board and finally determined that a particular spot of the RF shield, when touched shorted out the input voltage. This sounded exactly like the problem I was looking for! Inspection of the board showed a 1/4 mm size defect in the board just under the edge of the RF shield causing a trace to contact the shield and then ground. I put tape on the shield to insulate this, tightened everything and absolutely no problem.

I went back outside to measure the voltage from the house prior to connecting the BiasTee and all was fine. I noted, however, that ON/OFF switch seemed real smooth without much friction like its predecessor on the other 998RT. I taped it ON. By this time, I surmised either gravity or movement of wires inside the box when I closed it each time were causing the switch to drift into the OFF position.

The tuner has been absolutely flawless in operation since my evaluation and repair. Overall, I think this is another example of MFJ making a really good product but with some lack of quality control enough to have two difficult situations to have to diagnose and treat. I lost lots of time and effort here on this one. Be careful with this. I hope you have better luck than I did. It works fine, BUT!!!
K7GS Rating: 1/5 Mar 6, 2017 10:26 Send this review to a friend
Poor Quality Control  Time owned: 0 to 3 months
I hope the third one is a charm. The first two ordered through a well known dealer did not work. At MFJ's suggestion the dealer gladly took each one back and shipped me the third with no charges. The ordeal took nearly 4 months. No money, no tuner.

The third one seems to work as it should but I have had it for only a few weeks. I am hoping for the best. I feel sorry for the dealer who probably lost money on this transaction.

K4ELO Rating: 5/5 Feb 22, 2017 15:33 Send this review to a friend
Working good  Time owned: 0 to 3 months
I was uncertain about buying this tuner after many negative reviews, but I really needed something like this to tune my 43' vertical. A friend of mine contacted MFJ and was told they had updated the hardware design and the software so I bought it. After about a month, it is working perfectly. No problems.
K5AJ Rating: 5/5 Jan 20, 2017 11:56 Send this review to a friend
Mounted in Liquid Tight NEMA Box  Time owned: 6 to 12 months
Basis for 5 Star Rating:

-- All specifications were met.
-- No need to perform internal changes.
-- Flawless performance.

Time in service 8 months.

Installation: Elecraft KPA500 output - coax - MFJ915 - MFJ998RT - MFJ912 - Ladder Line - Random Length Dipole

Caveat: MFJ makes no claim that the 998RT is water tight. It is not. I knew that prior to purchase. My MFJ998RT is installed in a liquid-tight Hammond PJ18168H NEMA case. All penetrations to the NEMA case are sealed air-tight and watertight with silicone. The case also contains the MFJ912 and MFJ915. NEMA box was sealed shut indoors on a dry day. Desicant packets were added to the NEMA box prior to closure. NEMA box is mounted at the base of the antenna mast and 3 feet from grounding rods.

NEMA box liquid tight penetrations: Double Female UHF connector, 12VDC, Gnd, EF Johnson Ceramic high voltage pass thru.

If I lived in a dry climate, such as Arizona, then the liquid tight NEMA box would be unnecessary.

Performance: The MFJ998RT, in my case, tunes down the SWR sufficiently enough to keep the Elecraft 500 linear happy on all frequencies except the 12M ham band, which I don't use. I could diddle with the antenna length to allow 12M, but I won't bother. I was made aware of 3 other hams who mounted their MFJ998RT's in NEMA boxes, have enjoyed flawless service for a long time.

Recommendation to MFJ. Cut a deal with Hammond, to incorporate the PJ18168H with the MFJ998RT, or fabricate a metal bracket adapter to go inside the Hammond PJ18168H. Add instructions to the MFJ998RT manual for properly making the NEMA box penetrations liquid tight.
K9BW Rating: 5/5 Dec 13, 2016 12:56 Send this review to a friend
Satisfied owner  Time owned: more than 12 months
I have been using a remote tuner and a trusty Johnson tuner for a ladder line. But in new QTH at present I am stuck with a random wire and counter poise. Was using an SGC remote for years but they seem to be out of the Ham equipment and stuff wears out in time. After reading many negative comments on the web I chose this large MFJ tuner since I might go back to using my old alpha linear some day. Purchased it new. opened the box, read the instructions, set it up and for the last three years it has been a keeper. Through operator error I had to reboot the internal computer. I have had not problems with it finding a match. Unless one tries to go against the laws of physics, the turner works just fine. wire length and cable length are important factors which would affect any remote tuner. To re-boot the computer I had to remove the cover for the first time. I did not see anything that would indicate poor assembly. It was clean and neat. Also, it seems to handle a wider range than my very pricy SGC tuner. I really enjoy being able to jump around the bands. Not having to route 12Volts out separately to the turner like with the SGC is a nice feature. Not too much to add. Read the instructions and follow them... remember not all wire lengths and cable lengths will present an "in the range" impedance. That is true of any antenna tuner. Only structural thing I would change would be the seal around the edges. But if I mount it at the base of my vertical.. I will protect it from the elements.
K5AX Rating: 2/5 Nov 17, 2016 08:04 Send this review to a friend
Triple Failure  Time owned: 0 to 3 months
Screw me once, shame on you, screw me twice, shame on me, but I went through 2 of these tuners in about a week, and then had a third one sent and with 600W it arched over on 80M and fried the PCB. It did this 3 times. So double shame on me for asking for a third one. I was trying to tune an 80M quarterwave vert with it. Not that much off of 50 ohms at all. Poof! Others, as you can see have had good luck with them. So INT W..
W4LJS Rating: 5/5 Oct 11, 2016 08:10 Send this review to a friend
A Good Tuner and How to get it to tune easily  Time owned: 3 to 6 months
This tuner has been a nice addition to the station here. However, like some others I initially had some problem getting the tuner to auto-tune. The solution turned out to be quite simple. I reduced the Target SWR to a lower level. (The factory default is 1.5) This seemed to get the tuner to start reliably. (Tuning time may be a bit longer when the Target SWR is lowered.)

Overall the tuner has operated well and has been able to tune my 130 foot dipole fed with ladder line and a 4 to 1 balun at the output of the tuner without problems 80-10 meters.

W6OU Rating: 4/5 Sep 1, 2016 12:45 Send this review to a friend
How to initiate autotuning reliably  Time owned: more than 12 months
There is an anomaly with remote antenna tuners like this one. You have to furnish a signal to initiate the automatic tuning process. The signal level must fall within a defined range. If it is too low, the tuner will not sense its presence. If it is high, the tuner will assume it is a QSO transmission and will not react.

A problem occurs when the combination of antenna impedance, cable length, frequency, and the last tuner settings combine to attenuate the signal at the tuner to a level where it is not sensed. In this situation the tuner will not tune. Turning power off and on did not help. With a manual tuner, you can grab the knobs and force the tuner to tune.

My solution when the tuner does not respond is to switch to 160 meters and tune there. In my case, on 160 meters the last tuner settings do not attenuate the tune signal so the tuner always tunes reliably on 160 meters. Then I switch to the higher frequency band I want and tune again. Since the tuner settings are at 160 meters, the tuning signal is not attenuated so tuning is initiated.

"Resetting" the tuner by tuning on 160 meters works in my case but for others another band might be a better choice. Once I discovered this "trick" I can get the tuner to always initiate an automatic tuning cycle with 10 Watts.
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