I talked to Robert at MFJ Tech Service, here is what he said about the "Self-Resonance Killer™" (MFJ Registered Trademark). Robert, MFJ Tech: The “Self-Resonance Killer'' on the MFJ-989C is a device that at times aids in tuning on some bands. It's not necessary to have, old tuner didn't have it. They worked fine.

I have a similar tuner, but for lower power. Your fix is just a reminder for MFJ owners and others that the roller contact wheel needs cleaning at least once a year (whenever the receive audio gets scratchy while tuning). I use a can of old TV tuner cleaner. Dave K8WPE

Nice repair. I bought a similar tuner off eBay, the MFJ-969 (300 Watt version), for what I thought was a bargain, but it, too needed some work to get properly operational. Mine wasn't burned but its anti-self-oscillation switch was jammed and would not allow the roller to advance beyond it towards the rear of the coil. Seems the hex shaft and associated switch were positioned 1/16" too far forward so the fiberglass parts would strike the coil and not enter it between the windings as they should. I found that the shaft was just missing its rear-most circlip located just behind the coil assembly. Replacing the circlip (actually an "e-clip") and adjusting the switch's copper contact slightly fixed it and now the switch assembly works perfectly. I also found that the roller's forward and rear end stops were off just enough to make the roller stop hard on its sharp edge at the extreme edges of travel instead of on its side axle as it should. While this didn't affect the tuning in any way, it would have eventually caused a ding to form in the roller's edge so slight adjustments to the stops with a file were needed to make to make them work properly. That required removing the coil assembly from the case but that's not overly difficult. While it was out I also oiled the shaft bushings so now it turns quite smoothly.

Excellent video for you solid state folks. I was first licensed in 62, and I learned to tune up tube equipment without any outboard tuner. After I fried a few pair of 6LQ6s, I learned to tune to the noise floor first. Boat anchors are much easier matched (than solid state) to a properly cut wire antenna, but you still have to be close. My ARC5 XMTR has a roller inductor inside, for tuning (with the magic eye) to a ZEPP dragged behind a B17/B24. TNX FER INFO 73 W8IMP AR SK

Once again, I have now learned something important. I have learned how to tune my radio with a manual tuner. My friend kinda showed me how, but he was close, and you reinforced what I had been doing already. Great job. You can teach an old dog (me) new tricks.

Hi Kevin. A couple years ago I bought an MFJ-962D from another Ham. It would never work and had been occupying space on a shelf for over a year. After watching your post about restoring your 962D. I opened mine up and removed the MFJ part which sits atop the inductor coil (as you did) and now it tunes great. Thanks very much. Steve from the Earlybird net.

@michaelguest8480

7 ай бұрын

Excellent! I ALSO had a Problem With that "Self Resonator Killer" & had to REMOVE it COMPLETELY! So far it Tunes NICELY! 😃👍🇺🇲

I have known a few folks with that same tuner that had the same thing happen. At least 2 of them said they tuned up with 20 watts or so and then after increasing power and was talking, they began to smell something burning and one of them said they could see flashing through the meter with the lamp off. I bought one of the 962Ds at a hamfest used and I took that thing out and tossed it in the trash. I also reversed connection on the inductor so that maximum inductance corresponded to the lower frequencies and the reset the knobs on the caps so that "10" is maximum mesh of the caps just like the old style tuners did. I run a maximum of 500 watts in mine, but it has never failed me yet - no burning and tunes very easy. I also have a 989C that I am restoring and have already done the same mods to it. I think their "self resonance killer" is really a tuner killer !

@michaelguest8480

7 ай бұрын

I Had a VERY Similar Experience JUST Yesterday! 😠. I Did NOT Rotate the Coil Knob While Applying POWER to it! As Soon As I Increased the Power to : 700 Watts that Coil Began to SPARK! I have ALSO Removed that Damn thing & Will Have to Scrub/Clean the Burn/Char Marks off the Coil! ☹️😠🤬

I have the MFJ 989C version rated 3 KW It is interesting the coil size is the same as the 1.5 KW tuner. Many Ham Radio operators have the same problem at the same spot. My tuner was smoking right at the white insulator in the middle by the magique switch. I noticed some metallic shaving was present on the insulator and shorted out the wheel. It was smoking with only 500 watts. I removed the magique switch, cleaned up 3 years ago and no issues any more. 73 VA3VAD

@kb9vsb

5 жыл бұрын

That's were Mine burnt up. I already had it tuned to Ten meters hooked up a Ten meter Mobile turned the variable power all the way down. Unfortunately the Person who advertised these radios on EBay Had it so over powered to get 280 watts out of it the Self resonance Killer didn't stand a chance. I won't mention who sold the radio, however I wonder how many CB operators buy them and burn down their trucks, homes, or other vehicles. I will never buy any High powered Mobile radios again. I wanted a bit more punch on Ten meters. However if it sounds too good to be true, It is.

Hi there Kevin, Good point about puting power through the tuner while rotating the roler mechanisum. I nev had the chance to look inside the ATU for the C11/R210 that was my bread and butter radio when I was a radio opperator R.Signals years ago. We used to spin the cranking handle round at a fair old rate to tune the inductor, then just a quick tweak on the cap to show max out. If the box was anything to go on what the internal components were like. They must have been prety substancial. The box was cast Ali, about 5 1/16" thick. It would have been 14"x7"x5". It was mounted as solid as a rock onto the top carring tray, next to the R210 Rx. The whole set-up was supposed to be portable, carried by a mule. Poor soding animal. Along with a pair of 12volt, 75 AHC Batteries. It would be enough to criple the mule. 73 de John- Aka G0WXU

Since the last time I emailed you my station is up and running. Doing a 100 watts on all bands. Also purchased a new MFJ antenna tuner the 948 which works like a champ. Very happy with it. Got my end fed dipole about 35 feet up. Looking forward to the bands really opening up. 73s Rob, wa2fmh.

@loughkb

2 жыл бұрын

Lot's of activity, all the way up to 10 meters, daily. I've even heard a few signals squeak through on 6 meters recently. Have fun.

A very good video, on how to fix a MFJ METER, and to tune it the right way CORRECTLY GREAT work !!

Watching your back catalogue..... I got one of these that needs the same attention. Thanks for the video 👍🇬🇧👍🇬🇧👍

great catch showing the PI. L and T networks ! thanks for intro

T Tuners are fairly common, they have increased matching ratio for the component values they use (good value). However they allow a large number of sub-optimal matching solutions, and only one of them has minimum component stresses, all the others have increased currents and voltages which increases the likelihood that failure will occur at higher power. Essentially they have lots of ways to be tuned wrong. Usually the correct solution is with the largest value of capacitance and smallest inductance that achieves a good SWR. The SWR would be fine at low power at any of these other settings, but as soon as the power was increased the additional stress on the tuner could cause it to fail. One of the experts to consult on this topic is W8JI, and he states on his website: "The worse advice, when tuning a T network tuner, is to start with the capacitor mid-way and adjust the inductor for maximum noise or minimum SWR. On lower bands the capacitors should be set to maximum capacitance as a starting point. Normally halfway open is a good place for the higher bands, typically 15 meters and higher in a 160-10 meter tuner." He has more details on his site which can be found easily. Kool amp silver plating powder can be used to repair the copper showing after the carbon is cleared away. w6akb

Good video Kevin. Glad to see I tune up the same way you do. Cleaning that roller occasionally is probably a good idea.

Ihave the MFJ-989 that had the same problem. I also took the shorting bar out and tossed it. Didn't seem to affect the operation of the tuner. Another problem I had was that when I'd get the SWR down to 1:1, it would stay that war for a minute and then start creeping up. Cleaning the coil didn't seem to help. I finally checked the caps and found that the set screw on the end of the rotor was not all that tight. I loosened the lock nut of the cap and tightened the screw on the end of the rotor. That did it. No drift on the SWR any more after that. If you have a problem with SWR changing on these tuners, make sure that these screws are tight. 73 Tom W7WHY

Great fix Kevin. I agree with removing that mfj trade mark.

I love my 962D, it is not the highest quality but with a little common sense as you mentioned, it performs perfectly. I have the 998 also but have to turn knobs and watch meters to get full enjoyment :P

Old vid. But I took that anti-resonator bar out of my 962D when it was new. That thing is a known problem. I've run the tuner behind an AL-811 for years and never had a problem with whatever that bar is supposed to do.

Great job on that tuner now days I personally enjoy the benefits of a automatic tuner .

I had the same issue, sold the 969 versa tuner on eBay, I'd had it from new never had more then 100w through it. The buyer contacted me and said a capacitor was burnt out and returned it. That was 10 years ago, I never checked it ,just put it at the back of the shed. I'm digging it out tomorrow to have a look. Initially I thought I was a victim of a parts changing scam which was rife at the time.This rekindling of an old hobby is going to cost me !!!!!.

Rule is: YOU CAN ALWAYS LEARN FROM A FELLOW RADIOAMATEUR! NICE TO HAVE SAVED THIS MFJ 962D BECAUSE IT IS WORTH IT!

good job, gold hands! 73 from RK3T Team!

Thanks for the video Kevin. I think I have came across similar coil "self-resonance killers" before. Guessing that MFJ must have found the unused coil tended to resonate around at least one frequency within the operating range. (maybe at higher power levels??). My old roller inductor matcher sounds a little scratchy these days. Think I will try your contact cleaner trick.

Very good Kevin good move yes I would have done the same on the repair. And yes seems lot of that type of tuner same problem about , But Ebay Sales and buyers, never know on some cases, more and more sales quote NO returns as to Part changers and damage users..well explain and thanks for the effort made Kevin 73's dale

This turner really needs a complete disassembled, inspected and the components tested. Surface cleaning should only be the start.

This model tuner is very compatible and I think made particularly for the Ameritron 811 amp. So that is why the high power.

Kevin - The self resonance you're talking about is not between the roller connection wire and the coil. It's actually between each turn of the coil and the next. The ARRL discusses this in the 2010 handbook which I happen to have a copy of. This subject is covered in the chapter named "RF Design Techniques". However in the older handbooks (like in the 80's) its covered in the chapter named "Electrical Fundamentals" . Look for the drawing of a coil with little capacitor symbols formed by dotted lines shunting various turns of the coil. I first experienced this effect for myself when I was building a tuner and I couldn't get it to work past 15 meters no matter how I adjusted the coil. When I swapped out the roller inductor which had uniform spacing on the turns for one on which the turns got a little further spaced apart on one end I could get it to work. Not sure what MFJ is doing there. I have that same tuner over here and when I had the cover off I noticed that very same weird gizmo on the coil but I blew it off thinking "oh well , as long as it works".

I enjoy the videos Kevin - thanks. But for that part, yes you could have tried to fab from scratch, possibly on your new 3D printer :) but - why not just buy a replacement part from MFJ - assuming it's sold/available as a replacement part. The function is to short out that section of the coil so that it's inductance with its own self capacitance, does not become resonant. Have to know what that capacitance might be to know if it's truly a concern or not. If the part was not ridiculously priced, probably better to restore back to original design... IMHO as they say 73 WB2SMK

Air dried tooth paste or brasso polish cream and this brush for course cleaning and cotton tips for spot cleaning . The poor ham use corn oil drips in baking soda

Always enjoy your videos. By the looks of it, this roller inductor will never manage full power. The conductor wire is simply too thin, for higher frequencies. I've got a massive roller inductor and that one uses the same system, but done by hand. A bunch of fingers on a separate shaft, short the unused part of the inductor. I'm not an expert in these matters, but I guess that it is to prevent stray inductance. In an amplifier the output tank coils are also split up in different sections and also under 90 degree angles from each other. So for 160 meters, the inductance from all the coils is used and for 10 meters only the first part. If there is one long coil for all the bands, the unused part of the coil causes strays and influence tuning, I guess.

Great save Kevin. Keep up the good karma.

Very informative, I'm looking at buying the 300 watt version second hand, I think it may be wiser to buy a new one after watching your video.

Just adding emphasis to a point that just mentioned in passing: do not change inductance while transmitting, even at low power.

I took that rod out of mine and it works fine , always hangs up when it gets to that point

Really good video. I have the same tuner. I never tune with QRO, but that stupid doofer doesn't work anyway, even unburnt. I'll be heaving it out and putting it in the trash.

very useful to see Thank you 👍

nice from a new ham

Nice video.

Nice! I guess the roller in such mechanism doesn't make a tight contact, and may lead to sparking. There are many people reporting this.

People ask me how much it costs to get into ham radio. I tell them I started with borrowed equipment, so 'nothing'. Then you start buying stuff...

@jeromegrzelak8236

5 жыл бұрын

@Southeastern777 yep kg6mn

@SkyWire88

4 жыл бұрын

Heh-heh. I started with a borrowed Harvey Wells TBS-50D transmitter, and a Gonsett G-66 mobile receiver (I think it was). Also used a Heathkit V.F.O. for the transmitter frequencies. That was back in 1977. My "elmer's" extra equipment. What a blast I had with that stuff. Next rig ( 1980) was to build a new HW-101, and I still own that one. Just HAD to drop that in here, Cliff. See ya. Earle / WB3EFE

@rodneyjohnson4794

4 жыл бұрын

there you go, brother man!

how did you get the assembly that shorts the main inductor out of the assembly? i have the versituner II and it has the same "self-resonance killers", but mine keeps hanging up and not rotating enough to touch the coil. if i give a slight bit of rotation on the shaft of the "self-resonance killers", the part will rotate perfectly into place. ideas on how to remove that part, and how i can repair this (even if i can't remove the part)?

Nice video, Kevin. I am working on one, too. 989C. This is helpful information. Hope you are doing OK. Still in Indiana?

Kevin, pretty good mechanical fix. Not too terribly certain that goofy switch apparatus was necessary anyway. MFJ always adds on junky, kluged fixes and their tuners are famous for arcing over even when tuned. (That's principally because they use cheap coils with skimpy spacing.) If the new ham was going to run more than 100-200 watts, then he could rig a manual switch at flip it in the 65 region. But, then again, if he can afford an amp then he can afford a new tuner. Better still, just work QRP! 71/72 de k6whp dit dit

@KB4QAA

6 жыл бұрын

The shorting switch is a useful feature and not kludgy nor unnecessary. A little attention to proper procedures will generally prevent such arcing. However, hams are Amateurs, not trained professionals....

Thanks Kevin! Another great instructional video! Jim KF5AQF

Any idea of a part number for the roller inductor or atleast the flipper with the spacers and everything on the little shaft

@loughkb

Жыл бұрын

Call MFJ support.

MFJ manual: "Understanding power ratings. There are no standardized power rating systems for tuners. The names used (i.e. 3 kW Tuner) carry over from the time when amplifiers were rated by peak power input, and not the true RF power output... The FCC has changed the power rating system of amplifiers, and tuners no longer follow amplifier power ratings." Whatever, right? That burned switch thing you removed often gets stuck slightly off contact.The MFJ-969 has a lot of arcing problems.Tuner still works but slightly erratic at certain spots until it totally carbonizes.

ありがとう。とても参考になりました。

@loughkb

3 жыл бұрын

You're welcome. Glad it helped.

Great Video. A couple of questions... When I'm using an external tuner with a radio that has a internal turner (IC7300) is it suggested to turn off the radios turner when using the external? Also, I noticed when I do, then I tune using the external tuner the radios SWR reading is higher than the external tuner. Any idea the reason for the difference between the external and internal SWR?

@loughkb

3 жыл бұрын

Yeah, you don't want to 'stack' tuners. The tuner, or transmatch, has one job. Transform some complex impedance to the 50 ohms impedance your radio expects. There should be no reason for a second tuner if we're already converted to 50 ohms. As for the disparity, look at the coax you're using to connect the radio to the tuner. You could have a bad or dirty connector, bad coax, or the wrong coax. i.e. 75 ohm instead of 50 ohm. Also, you want a ground wire between the tuner and the radio so their chassis's are at the same potential.

@FlattyDaz

2 жыл бұрын

@@loughkb The length of your patch lead, more than likely.....

Hi Kevin, Wonder if that damage was done after it was sold on Ebay. Nice repair video. 73 WB3BJU

@loughkb

6 жыл бұрын

Yeah, most certainly it was. It was fine when Al sold it. The guy who bought it screwed it up. Ebay always sides with the buyers though, so he didn't have any real recourse.

@leslieaustin151

6 жыл бұрын

Hmm, a shame buyers (and sellers?) are dishonest like that. Screw it up and hand it back is pure meanness. Les

@loughkb

6 жыл бұрын

I've heard of even worse. Someone selling a piece of office equipment, getting it returned as broken, and finding missing parts inside. The buyer just wanted parts and totally screwed the guy. I've done quite a bit of ebay selling over the past three years and so far, no problems. It's not that common, but it sucks when it happens.

@warplanner8852

6 жыл бұрын

Kevin Loughin, if you document these carefully, you WILL be able to get eBay to side with you as the seller.

Whoever is getting that and that radio is a lucky dude. ...and likely handsome. -- 73's KD9HUM

@ri3cjoh

6 жыл бұрын

It's me.

I have one when you tune it at five watts it is OK but at 100 watts out the coil sparks

Thank you I have the same Tuner and it did the very same thing. Lesson learned .Do NOT hook up a Galaxy radio to your MFJ 962D Tuner. I blame the Radio. All kinds of Spurious and deadly emissions! I am Glad however that it isn't a total loss. With a clean up, good Coax, good Coax length and antenna; A good signal will get out much better than high wattage!

Would an UNUN not make that MFJ962D obsolete (not required) since the UNUN matches the long wire antenna to the transceiver.

@KB4QAA

6 жыл бұрын

No, not at all. An Unun, is a 1:1 transformer. It will do nothing to match the 50 Ohm radio to a ? Ohm antenna.

Did you think of modify it from T match to a S match?

Hello Ken, thank you for this video, may have saved my butt. I have this same roller inductor in my MFJ-962 E, on the other side of my desk is a MFJ-962 D, in my mind exactly the same tuner ? The 962 E is new out of the box, and seemingly the roller does not follow the coil like it's supposed to, again ? While MFJ do have a "warranty", the Canadian store I bought the tuner from offers no warranty, and the buyer gets screwed into buying a different tuner or send this one back to MFJ who are now out of business, My question, instead of the CHINCY part used to short out the coil automatically, why not modify and adapt an electric switch to the front OR, take out the mechanism entirely, in my mind this is MFJ's method of adapting to 1.5 KW, (800 W) How did you make out with the tuner in this video, without the self resonet inductance gadget. Did it work for you ? VE6JRR Jim R

@loughkb

2 ай бұрын

It worked fine without the part.

@jimrussell6891

2 ай бұрын

@@loughkb It works for me as well, took it out last night and ran 600 W through the tuner, perfect. Thanks again VE6JRR

what a shit, they should pack a toothbrush inside the packege as standard. I hate that I am a MFJ owner. Made in USA but worse asembly than china in my case MFJ 945E.

Kevin could you send a link to your coax repair video , i looked and couldnt find but i know youve one pls

@loughkb

Жыл бұрын

Coax repair? I'm not sure what you mean or what vid that might be. Could you elaborate on what you need to do?

@jasoncreed6396

Жыл бұрын

@@loughkb oh sorry ya i meant you had one on “f” connectors

@jasoncreed6396

Жыл бұрын

My mag mount shield was damaged because i routed it poorly

@loughkb

Жыл бұрын

Ah. You can't really repair it. You could chop it and put connectors on it so you could use a barrel connector in line. The best route is to just replace the whole length of coax.

@jasoncreed6396

Жыл бұрын

@@loughkb ya i had a feeling. But i went and bought the barrels (“f” connectors) and the tools to do the job .But your right Kevin ill just replace it.but it means pulling apart my mag mount and gosh im lazy lol. Probs just repurchase the whole darn thing🙄.Well thank Kev. And i love your channel…probably said that already but your one of my go to guys:) Thanks for gettin back so quick like, i appreciate it. Take care. PS decided to pull er apart and fix it …figured it would be a good chance to get some experience with coax and i like to understand how my stuff is built and often i think peeps would be surprised just how often i find mistakes made from the manufacturer and there is almost always ways to beef up or improve the product in some way or other.pulled apart my blender the other day cause it was vibrating badly and i think thats the reason it was disposed of at value village…brand new model and it took me 5 minutes to realize a rubber grommet was upside down! Now she runs like a charm:) anyway …. The mag mount weather proofing is the weak point with tram and ill correct it but otherwise ,i gotta say im impressed with the design.It was easy to pull apart ,diagnose and even if water got in ,the way its designed i doubt it would cause any problems…excellent product for the money.

P.s.love your vids:)

Kevin, next time use carburetor cleaner. 73s

MFJ doesn't sell that broken part? I thought they were pretty good about this.

What antenna was you using ?

@loughkb

5 жыл бұрын

When?

@handyparts

5 жыл бұрын

Kevin Loughin when you were using the tuner on all the different bands

@loughkb

5 жыл бұрын

I'm sorry, but that was a long time ago, and I just don't remember.

@handyparts

5 жыл бұрын

Kevin Loughin that ok it have have been a g5rv

JE VIENS DE FAIRE L'ACQUISITION d'une MFJ -969 Deluxe versa tuner II je ne maitrise pas tout a fait son fonctionnement sur ttes les gammes ...à bientôt mais c'est une "chouette" boite d'accord . 73 F8FSN

Didnt know you could trademark junk.

I DON'T REMEMBER AND YOU DIDN'T SHOW THE 725, DOES THE 725 HAVE AN SWR METER ON IT? IF SO AFTER GETTING THE MATCHER CLOSE, USE THE RIGS SWR METER TO TOUCH IT UP IF IT HAS ONE. THE RIG SHOULD BE FLAT SO THE RIG DOES NOT FOLD BACK. NEVER SAW THE INNARDS OF THAT MATCHER BEFORE SO THANKS. I REALLY LIKE MY TENTEC 238 AFTER THE CENTURION. I DON'T FEED ANY POWER TO THE 238 SO CANNOT SEE THE METER SO I USE THE SWR METER ON THE TS2000X INSTEAD. AS A FINAL CHECK THE WATT METER ON MY DRAKE C-4 IS THE FINAL OUTPUT INDICATOR. YES IT SHOWS A LOT OF SWR AT TIMES BUT THAT SAYS THE RF IS GETTING OUT AS GOOD AS IT CAN THROUGH THE MATCHER AND THE TRANSMITTER AND AMP AT LEAST ARE HAPPY :-) MERRY CHRISTMAS. KØOJ

@warplanner8852

6 жыл бұрын

OJ Jenkins, we get it. You don't need to shout!

@ojjenkins7110

6 жыл бұрын

WELL WALT, YOU DO NOT HAVE MY VISION, AIN'T YELLIN!!

so does it work without it?

I think having a roller inductor makes you want to adjust it while transmitting. How many turns does it take to go the full range of inductance? 100? more? Imagine the time consuming procedure of adjusting it a turn, then transmit, the unkey, they adjust another turn and transmit. Very time consuming! They should have made it so 20 turns covers the entire length of the coil. That's why I went with the tapped inductor and wafer switch. With it I tune up in seconds, not minutes. Same end result but much more efficient.

@loughkb

3 жыл бұрын

I always recommend people drop the power on their radio before tuning so they don't damage the finals. If you've got a 100W capable radio, just drop it to 5 watts and tune while keyed. Running the finals at 5% of their rated power keeps them safe.

@johninjersey

3 жыл бұрын

@@loughkb Right but at 5 watts would you still unkey to adjust the roller inductor?

@loughkb

3 жыл бұрын

@@johninjersey No. At that low level, you're not going hurt the tuner or the 100W capable radio. If I had a QRP radio, I'd drop it down to 1.

Will this work on a CB 11 meter

@michaelzehrfeld7766

4 жыл бұрын

Sure - no problem...

They should rename that piece of junk the "Tuner Killer" ! It's not needed and the tuner works fine without it ! I removed mine before it ever had a chance to burn because I have seen them burn with just 100 watts !

Hi Kevin thank you for getting back to me. I misplaced your email. I would like to send you some pictures of my station setup. Also my end fed dipole. If you could send me a quick email that would be great.

Thin metal. Mfj quality!!!

I just couldn't take it any longer... around the 13:00 min. point, all I could ask was... WHAT? Have you ever heard of replacement parts? Not sure, even though I have two MFJ tuners, but MOST companies can make money selling replacement parts on almost all models of this gear. To not even MENTION this seems weird. de KQ2E

@forgetyourlife

4 жыл бұрын

Covered in the last minute genius.

@paulcohen1555

3 жыл бұрын

Companies can make money selling parts to fix their design errors.