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Reviews For: MFJ-998RT Remote Auto Tuner, 1.5 kW, 1.8-30 MHz

Category: Antenna Tuners/Matching Networks

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Review Summary For : MFJ-998RT Remote Auto Tuner, 1.5 kW, 1.8-30 MHz
Reviews: 50MSRP: 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
More Info: http://www.mfjenterprises.com/Product.php?productid=MFJ-998RT
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
24503.4
KE7FD Rating: 2023-01-06
The only game in town if you want high power remote Time Owned: 0 to 3 months.
I've got two of these; one brand new and the other is a few years older. Both work as advertised but the new one tunes a bit faster; newer components I guess. The only complaint I have is you need to disassemble it when you pull it out of the box to tighten things up. Along those lines the insulated posts are not especially secure and tend to work their way loose, so I replaced the stainless steel bolts on the posts with some that are a bit longer so that I could add lock washers in all the key places. You don't want to over tighten the posts because they could fracture since they are ceramic. Don't skip an initial going over! The last thing you want to do is to simply deploy it only to find out you've got loose connections. Take the time, make the effort to tighten things up as well as going through the manual. If the other MFJ remote tuners of lower power rating are like this one, you will want to check things out just the same. I am able to get 80 through 10 m tuned on two different doublet antennas. I wish there were other legal limit remote tuners to choose from but there simply aren't. I think MFJ is fully aware of that which could possibly contribute to the sloppy craftsmanship during manufacturing. Depending on your application / antenna you may find it necessary to connect a balun at the output. Also you may find it beneficial to put an RF isolator / choke on the coax feeding the tuner. This also, your mileage may vary. Using the tuner is as easy as keying down with just a few watts. I found it tunes better with 15 to 20 watts than it does with five watts. Sometimes it takes longer to find the right tune with lower tuning power but I was able to go through every band and find good low SWR with 15 to 20 watts. Also, I believe there is a setting where you can decide what is an adequate SWR for your purposes such as 1.5 to 1 or perhaps lower. Once you get the tuner installed you may decide to change that and again depending where you have it installed that could be a real pain in the neck. I know with the desktop 998 this is the case so changing the level is much easier. If you're using a doublet antenna and through previous testing you are pretty certain you can squeeze a really low SWR by placing a tuner at the feed point of the ladder line, you might consider setting a lower SWR threshold than 1.5, but that's up to you.
VY0AW Rating: 2023-01-05
Working well Time Owned: 6 to 12 months.
This is my latest review of this tuner:
It has now been in operation for about eight months without any problems at all. I have operated at 1.2 Kw and it has performed properly. I find it best to tune up at about 30-watts.Do not tune up at high power or you'll likely kill this tuner, but, operated correctly it works very well.
A big, easy-to-read SWR meter like the MFJ-868B is almost a necessity and it's fun to watch the tuner find a match, which takes between one and five seconds.
The enclosure does not appear to be very weather-proof. I built a "house" for the tuner and I think that might be advisable in most situations

Earlier review:
I have the MFJ-998rt located about 50-feet from the shack and installed inside a home-made enclosure with a 1:1 balun. The tuner is fed with RG-213 and I'm using the bias tee. The antenna is a 130 foot dipole with the centre up 40-feet and the ends at 10- and 20-feet. It's fed with 40-feet of home-made open wire feedline.
I'm able to tune any amateur band from 80 to 10 metres with SWR 1.5:1 or less.
I'm quite happy so far, but I've only been testing it at 100-watts. Can it really take 1.5 kw? We'll see when my new amplifier (Ameritron AL-82) arrives in a few weeks.

First review:
This is just a preliminary report. It's still too cold here to do any antenna work.
Took it out of the box - something was rattling around inside. Opened it up (one stripped cover screw). Inside a screw had escaped from one of the shield mounting holes. Easy fix. The interior looks good.
Tested it on the bench into a dummy load. It had no problem matching the dummy load - HI! Hooked up the bias tee and 12-volts. No 12-volts out of the bias tee! Opened that up - one pole of the power switch had not been soldered to the board. Fixed.
NY2KW Rating: 2022-09-26
Outstanding After 3 years Time Owned: more than 12 months.
UPDATE: I added an EFHW 80-10 sloping dipole rated for 3kw and the MFJ-998RT has worked perfectly with it full legal. I do have a remote power switch to reset the Bias T power and now and then I have to the autotuner remember a new set of tuning parameters. Most surprisingly, it tunes the EFHW 80-10 on 160 and I have worked almost WAS plus lots of Europe and Caribbean with 200-300W on 160m, a real bonus

************************************.
I was reluctant to buy this based on MFJ quality history but I bit the bullet. I first had it mounted on a post remotely, matching a multiband dipole with ladder line. Had a direct lightning strike vaporing the ladder line but the grounded tuner never was damaged. I next used it to match a multiband vertical, all worked perfectly until one day it started acting screwy, constantly retuning at QRO. Since we get lightning storms 8 months of the year I was convinced it must had had an EMP hit of sorts. Took it down at it was working well... long story the gardener a week before aerated my lawn and i found 3 spots in the superficially buried coax torn open and water-logged. Replaced coax and the tuner works perfectly again. Congrats MFJ on a fine piece of equipment.
KL7EZ Rating: 2022-05-20
MFJ-998RT Remote Auto Tuner (Good So Far) Time Owned: 0 to 3 months.
General

Purchased the unit new from DX Engineering in May 2022. These tuners are a challenge to find new on the shelf these days. I read all the eHam reviews that were posted and decided to give the tuner a chance. I have a Zero-Five 43’ vertical with elevated radials and an additional 90 or so, buried radials, 43’ long, made of 14 gage insulated stranded Cu wire. The radials are spread out symmetrically around the base of the antenna. I grounded the tuner to a DX Engineering SS ground plate with 2” Cu strap (provided by Georgia Copper). The antenna is located approximately 300’ from the operating station. I buried 300’ of LMR 600 from the operating station to the antenna base. I have been operating this setup with a Palstar AT2K manual tuner inside the shack with great results. The Palstar can 1:1 match any frequency on the vertical antenna from 80 -10 meter. As with any setup, I wanted to experiment a little. I wanted to see if a remote MFJ full power handling tuner would work better if placed at the base of the antenna. I built and set a two-post wood panel and attached a sealed Vevor weatherproof 24” W x 24” L x 12” D wall mounted junction box to the wood panel. I installed the J-box & panel at the base of the antenna. Thinking that the J-box and tuner would get hot when placed in the hot Tennessee sun, I wrapped and taped the exposed J-box with aluminum floor & tunnel shield (supplied by Summit Racing Equipment – part No(s) DEI-050503 & DEI-010413). I got this clever idea from another ham that wrapped the plastic cover of his MFJ 998RT. He and I both live in the southern states where summer temperatures could heat up the black cover of the tuner above its operating limitations. So far… @ 93F sunny conditions, the internal temperature of the J-box and tuner has not exceeded 100F (via Davis Vantage Pro 2 Thermometer probe).

Installation & Operation

I read the manual a couple times prior to installation and followed the guidelines. I removed the black plastic case to access the mode, tune and menu function buttons. Removing the cover also provided a means to visually inspect the internal system prior to commissioning. I attached the tuner to a 2’ x 2’ Cu plate installed inside the J-box. I utilize 13.8-volt DC at the panel via the 2.1mm power connection on the back of the tuner. I didn’t use the bias Tee option. Before startup, I reset the unit to factory defaults (total reset) and deleted the entire memory banks. I set the Target SWR to 1.1 (factory setting is 1.5).
Initial tuning on each band took a little while (30+ seconds) for the tuner to memorize the relay’s balancing of capacitance and inductance. I set the transceiver output power to 10W while tuning. Once the tuner finds a match, tuning within a few kHz of the matched frequency takes a fraction of the time to tune. I noticed when switching bands, I needed to cycle tuner power to encourage the tuner to match properly. I strongly suggest ensuring there is a means to cycle power at the operating location. This is a lot easier than walking to and from the tuner to cycle power. All and all, the tuner seems to work well. I haven’t exceeded 100W yet. Once I feel that the system is working properly, I’ll connect my amplifier.

I have noticed that the tuner’s SWR display at the base of the antenna is lower than the SWR display located at the operating station. For example, the SWR at the antenna base frequently finds and displays a 1:1 match and the station’s Telepost LP-700 wattmeter displays approximately 1.6:1. My next step is to provide a SWR bridge calibration. This may more closely align the separate SWR readings. I placed a dummy load at the antenna base and found the SWR of HF frequencies to be very close to 1:1 through the 300’ of LMR 600. There will be a little loss due to resistance within the 300’ of LMR 600, but not enough to cause a 1.6:1 difference. I'll post an update in a year or so.

73 Scott – KL7EZ
Gallatin, TN
W8TZ Rating: 2022-03-30
Not perfect but it does work Time Owned: more than 12 months.
I have had this tuner about 4 years. I have used it with a single 150 foot long wire and also with a 160 meter loop antenna. I am presently using it with a 160 meter loop and a 4:1 balun. It works well with both antennas however it does have one annoying quirk. Sometimes when changing bands it refuses to tune properly. The cure is to cycle power to the tuner. Not a big deal since the power supply is located in my shack. I have the tuner mounted in a shed about 50 feet away from my shack. It is fed with coax and I am using the bias-Tee that is supplied with the tuner. For the most part it works great. I drive it with 700-800 watts most of the time with no issues. The only problem I have had is with the 2 germanium diodes, D44-D45 in the SWR circuit that opened up due to a lightening strike. They were relatively easy to replace. The only other minor issue is with the screws that hold the plastic cover on the unit. Several of the holes for these screws were stripped.
KI6R Rating: 2021-06-22
Some QA issues. Tunes 1/4 wave 80/40 on all bands except 60m. Time Owned: 0 to 3 months.
6/2021 purchase of a new 998RT. QA: Several cover 6-32 screws were barely finger tight. One screw was cross-threaded in the nut-insert. Re-tapping the insert and replacing the screw fixed it. The cover does not fit well. MFJ should consider moving the nut-inserts outward toward the frame edge about 0.05". Then replace the 6-32 screws with 1/4" longer and include flat washers on them all. The antenna wire binding post was not fastened tightly enough. I had to re-tighten it after installation. MFJ needs to carefully torque this feedthru and use red LokTite on the threads.
I have the tuner mounted 21 ft high on a chimney and I am feeding 80 and 40m end-fed 1/4-wave wires that are in parallel, spaced about 30 degrees apart and only 15-20 feet high. The ground system is about 375' of copper cable on my roof lightning rod system. A 5' length of 4" wide aluminum strip ties the tuner to the lightning grid. I also have two 1/4 wave radials on the 60, 40 and 20m bands spread out on the roof. The tuner tunes this antenna on all bands 80-10m except 60m. 60m tested at 1500-j1400 Ohms impedance which is much too high to tune. It tunes 1.95 MHz to about 2.0 VSWR, and 50.1 to about 1.6 VSWR. No tuner VSWR on 6m is about 5.2, or 131-j133 Ohms.
60m seems to be difficult to multi-band with 80 and 40. I hope to add another (3rd) wire somewhere near 1/4 wave long on 60m to see if I can lower the Z enough for the tuner to tune. 73, Ed, KI6R. Tucson.
WA3SIMI Rating: 2021-03-22
Good value. Not intelligent. Time Owned: more than 12 months.
I've used this tuner for about one year with an inverted L vertical antenna.
There are some things you need to learn and understand before getting comfortable with this tuner. Since it's a remote tuner I recommend removing the cover and running it in your shack at first.

It has worked flawlessly on the Bands 40 and higher.
I have a short 160m antenna with a loading coil which has required a lot ground engineering. Running this tuner on 160 has been a challenge. I have improved my ground system and now things are working great.
I am not faulting the tuner because I'm asking a lot.

For my compromised antenna situation, I have added five common mode coax chokes.

The tuner doesn't want to see more than 25 watts when you're doing a long tuning. I have found that I need to run 50 Watts after the initial low power tuning to get the best results. Otherwise the SWR worsens with higher power. I mean the ratio not just the reflected power.

I have set the target SWR and SWR retune window to the lowest values.

If the SWR is not nearly perfect, then I reset the power. It's important to have a power reset capability when the tuner is mounted remotely. That way you can force it to retune.
I have RFI problems therefore I need my SWR to be nearly perfect.

This tuner allows me to work every band between 160m and 10m. That includes 30 m and 60 m. Once it's set up it's a great system. My inverted L is 60 ft long and 25 feet high. I use a relay to bypass the 160m loading coil. High voltage is will develop across the coil.
I use two sets of contacts in series. Teflon tubing on the wiring.
I have two common mode chokes between the tuner and the antenna feed, made of ferrite beads.
I had issues with a toroid wound CM choke in this position and had to remove it. I think the counter EMF on sideband and fast CW pulses presented a problem to the tuner.







WA6III Rating: 2020-11-27
Received new 26AUG2020, so far, works great Time Owned: 3 to 6 months.
Just got the MFJ-998RT to replace my 23 year old SGC SG-235 Smart tuner.

So far, it works as good as my Smart tuner. tested it with a 300ft end fed wire, 5--135ft radials and up to about 1200W using a Henry Radio SS750 and a Drake L-4B

It worked fine right out of the box. So far, no complaints.

---------------------------------

3 months later......

Update on the 998RT. Still no complaints! I have since changed to a 240ft center fed dipole fed with 450ohm "window line" and a Balun Designs 1:1 balun. Using this tuner, it tunes 1.8-2.0, 3.5-4.0 7.0-7.3 etc.

I get consistently better signal reports from the same people that heard me using the 300ft end fed. The 240ft center fed dipole is in the same position the end fed was in.

Still a GREAT rating!



73/Rick/W7IMM


AE5I Rating: 2020-09-16
A Great Product at a Great Price! Time Owned: 3 to 6 months.
I bought an MFJ-998RT to match my end-fed wire antennas at the feedpoint. I have around 150’ of coaxial transmission line between the rig and the feedpoint so I decided to go with a remote automatic unit rather than continuing to use a tuner at the rig. The matching range and the power handling capability made the 998RT a good choice. It has come up with a good match in every case so far.

I’ve had the unit in service for 3 months and it has worked just as expected for the whole time I have had it. It reliably matches my 75’ inverted V as well as my shorter sloper (on the higher bands) without any trouble. I use the MFJ-4117 power injector and it has also worked as expected.

I couldn’t be more pleased with the 998RT. I would buy it again without hesitation and would recommend it! I give it a very high rating because it does exactly what I bought it to do. I have used other automatic tuners in the past and I like the 998RT better than the others that I have experience with.
W9OD Rating: 2020-08-28
Keeps on Ticking Time Owned: more than 12 months.
I have a ZeroFive 43 foot vertical with 40 radials. It is close to 200 feet away from the shack. It did okay with the internal tuners in my K3 and KPA 1500. It was suggested that I could improve my performance with a remote tuner. I purchased my MFJ 998RT at Dayton about four years ago. Got it home and put it online. It has been doing a fine job ever since. I am on the air almost daily. One time I hit it with 1700 watts (by accident) I thought it would be toast, with a sigh of relief it did not hiccup. I rarely fun more then 1 KW. I would not hesitate to buy another if needed. W9OD