MFJ tuners really that bad?

Discussion in 'Amateur Radio Equipment Reviews' started by KF7WMM, Oct 19, 2013.

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  1. WA1R

    WA1R Ham Member QRZ Page

    I have had four MFJ tuners and each one has been dependenable. I esepecially liked MFJ's MFJ-986, the butterfly or split-stator crank tuner, although the tuner I still wish I had was the 989. That was a great tuner and could tune up about anything from a bed spring to a barrel. I know that every brand has detractors, but I have always had good luck with K5FLU's equipment and I've been around for about 34 years in this nutty hobby, so I think I've picked up a think or three in my journey so far. In fact, I'm back to a tube rig again and I'd give my autotuner for the 989, especially it's built-in dummy load. Good luck, de WA1R
  2. WA4OTD

    WA4OTD Ham Member QRZ Page

    I have two MFJ tuners and they work ok, if they misbehave I just take apart and resolder connections, tighten screws, etc and they always seem to work again. Contrast that to the Daiwa CNW419 tuner that works perfect, tunes anything, has always worked, feels solid and is my primary tuner.
  3. KF7VXA

    KF7VXA Ham Member QRZ Page

    There was just an article in QST comparing different manuel antenna tuners. You may wish to read it.
    From what I saw, the MFJ tuners have more power loss through coils and resistance than some of the others, but the one's with the least loss of course are the most expensive. I have one and it works fine with just 100 watts. 160 meters seems to be the one frequency that causes the most problems in tuners. If you plan on working 160 a lot, I'd get one of the more expensive tuners (just my two cents)

    I think it's a good idea to always buy a tuner that will handle more wattage than you plan to use. Much less chance of arching or other problems.

    I make it a practice to open up anything I buy from MFJ and check out the mechanics and solder joints. My tuner had a problem with the wiper on the coil. I was able to fix it easily myself, but it should have been right to begin with. I also just bought an Amp meter, one that goes in line with your coax and the meter sticks sometimes because the adjustment screw for the zero is lose. I'll have to pay to send that one back. The voltage booster I just got works perfect.
    I guess it's a roll of the dice with MFJ anymore, but most products seem to work.

    73's John KF7VXA
  4. KG4LLQ

    KG4LLQ Ham Member QRZ Page

    I have owned a 949E for over 10 years. After just receiving it, I had to tighten the hex-nuts on a couple of the controls so they'd work properly. I now rarely use the "tune" function, using it more-or-less for the ability to connect two antennas and switch between them in the "bypass" mode. The meter is an "estimate" of actual power; but it gives a reasonable idea of transceiver output & SWR. In terms of value vs. price, I'd say it is an OK product which performs as advertised. In terms of antenna tuners, I believe, if at all possible, operate with resonant antennas even if it means limiting your operating bands to only two or three. "Antenna tuner" is a misnomer. These devices simply protect the transmitter finals from a gross mis-match. Past the tuner, the antenna is still mis-matched and loss is evident along the coax (unless a balanced line is used). Therefore my advise is to use an "antenna tuner" sparingly and opt for resonant antennas instead. 73, Ken
  5. KE4YOG

    KE4YOG Premium Subscriber QRZ Page

    I had a Palstar AT2K. I absolutely loved it but alas I forgot to disconnect that antenna after doing some work one day this Summer. While I was out eating had a thunderstorm and it zapped by TS-480HX. I sold the Palstar and used some of the proceeds to cover the deductible from the insurance repair. I have a MFJ-949E that I use now. It is doing well but I checked it inside and out before using it. The next thing now is to save up to buy another Palstar.
  6. KD7TWI

    KD7TWI Ham Member QRZ Page

    If I were to get anything I would buy what I have now. Find a nice used Tokyo Hy-Power HC-200AT auto tuner and forget about problems. I wanted to really see if it would tune a gutter and low and behold, not only did it tune it I made a couple contacts. I also have a MFJ manual tuner that I use with a Ameritron 811H and a Alpha 374 and it has not given me any problems with either amp. I did tighten everything up inside when I got it just to make sure but its just what you do with anything MFJ, its a known issue. I think they make good gear at an exceptional value.
  7. NO2A

    NO2A Ham Member QRZ Page

    I have the MFJ 989C tuner. I use it with my 80m dipole fed with 450 ohm line. It matches quite well on the lower bands,even 160,where my rig sees a perfect match. It`s been fine with my AL-80A amp. Some of the higher bands,like 15,10m,are a little more difficult to match,but it will work. If I was going to buy a new tuner I`d get the 989D or ATR-30,as they have even more matching range. I wouldn`t get anything with less matching range,that would be a waste.
  8. PA1ZP

    PA1ZP Ham Member QRZ Page

    Hi to you all

    The MFJ's and LDG's are not that much different.
    If you have an auto tuner that can handle Z from 16-1000 ohm, you might run into problems with high reactive impedances and certainly a wire antenna can produces Z or R's from far over 1000 ohms or very much lower as 16 ohms.
    If you do not know that a wire antenna is something else then a random wire as an antenna, you might get failures more often, and you didn't read the manual carefully enough or didn't understand what the manual was saying.

    The Q.C. at MFJ is a bit of now and then, but my little MFJ904H does precisely what the manual says it does.
    The MFJ 949E or F i had and gave away did what MFJ said it could do.
    The other 2 MFJ's that I repaired for a friend, failed because of not having enough knowledge in how to use such a device, and one failed once before because of unsoldered static plates in one of the capacitors, truly a MFJ Q.C. failure.
    The static plates of the antenna side capacitor were held in place by the connecting wire to the inductor.

    I think that with open wire fed antennas the little 1N34 diodes in the SWR bridges fail very often due to high voltage static charges from the antenna.
    I replaced those with cheap found Germanium diodes which were both the same and I even do not know what type they are, but on the other hand diodes in all my balanced tuners failed once or more times in the past due to high voltage static.
    But the ones with the 1N34 failed within 100 hours of use on all 4 tuners that had them.
    Some tuners took far over 5000 hours of antenna connection to fail the diodes.

    But every once in a while I hear my unbalanced out PL-259 socket in the "Soyuz tuner" spark when it rains overhere.
    That is because the center contact it is connected straight to one of the balanced outputs.
    It is a silver plated PTFE isolated (teflon) chassispart.
    I think the MFJ 9982 will have the same problem as it has the same spark arrestor build in hihi.
    My homebrew Soyuz is build like the AT4K or MFJ9982, but then with a weight of 50 pounds and welded plate capacitors and an USSR roller inductor, that makes the MFJ and Palstar roller inductors and capacitors look like cheap low Q toys.

    If you have static voltages that high on your tuner these germanium diodes may fail , any one should know that.

    Quality of the Soyuz tuner is awfull, no warenty, no manual, no E-mail adres for help, no telephone number for help, no customer service, no specifications, nothing, because I designed and build it myself.
    And if it fails I have every part in spare.
    I used a wrong setting on 40 mtrs and the Antenna C started sparking with 400 watts, I had to know the setting was of and producing very high level voltages, because I also build and designed the antenna system myself.
    i knew I was feeding a very high Z system in almost a full Voltage point on the openwires at the tuner.
    If you look at this movie that was made with only 100 watts of power aplied on 40 mtrs you see how high the electric field voltages are at the tuner.
    I readjusted and no problem even with 3 times the power.
    Maybe a tip for a very cheap feedpoint voltage indicator for someone that hasn't got the tools to measure feedpoint Z in openwires.
    You can see on the You-Tube link how to build one.
    If the light burns on TX as my light does your MFJ 300 watts PEP or LDG might get in to troubles due to very high Z and voltages.
    Low Z is not to be measured with this methode.
    You would have to place the light 1/4 wave away from the tuner at the open wires to measure low Z with this methode.

    73 Jos
  9. KF7WMM

    KF7WMM Ham Member QRZ Page

    Thanks to all for the replys,I have talked to balundesigns and he feels I most likely have low impedance on my 124.5' wire the way I have to deploy it,horizontal V with the open end only 25' apart.the length is from his advice..He thinks try shorter lenghts or maybe a 4:1 unun instead of my 9:1..coax fed with radial on roofBob KF&WMM
  10. K8JD

    K8JD Ham Member QRZ Page

    I have been using MFJ Tuners, QRP rigs, etc for many years.
    I have a 948 tuner that developed an intermittant that required replacing a wire ground with a piece of copper braid.
    That was years ago and I still use it today..
    My latest is the MFJ974HB. Got it last year to experiment with a balanced feedline fed doublet. It has worked very well for me.
    I suggest to all, that it is the tuner to use for non-resonant dipoles fed with ladder or twinlead, and NOT the unbalanced (T network) tuners with a built in fixed ratio (usually 4:1) BalUn.
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