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Reviews Categories | Antenna Tuners | MFJ-976 Balanced Line Tuner Help


Reviews Summary for MFJ-976 Balanced Line Tuner
MFJ-976 Balanced Line Tuner Reviews: 9 Average rating: 3.9/5 MSRP: $499
Description: 1500 watt Balanced Line Tuner
Product is in production.
More info: http://www.mfjenterprises.com
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WB4YFK Rating: 5/5 Feb 8, 2014 21:33 Send this review to a friend
Works fine, No issues  Time owned: 0 to 3 months
Picked up my 976 at a local hamfest. It was in the original box still in plastic with manual. Owner said it was never used. It looks brand new. I use the tuner mostly with my TS-870 but occasionally fire a 500 Watt amp into it, no problems. My antenna is a 40M folded dipole and I have used the tuner to operate 40,17,15,12 and 10 meters with this antenna. I have no way of measuring the efficiency of the whole system but the rig and amp are happy and I've made contacts(mostly SSB) all over the world. This tuner with the balanced T configuration did clear up an issue I was having with RF in the shack using a tuner that used a torroid balun between the antenna and tuning elements. I'm very happy with that. Some might argue with an great rating but everything needs to be considered. There are places where I would rather see ceramic insulation but if they did that the price would not be where it is so because of reasonable tradeoffs in cost/quality I consider it a great buy.
 
WA3DQS Rating: 5/5 Jan 8, 2013 10:32 Send this review to a friend
Still like this tuner a lot !  Time owned: 6 to 12 months
After almost a year of using this tuner with a 1KW amp and a non-resonant loop antenna, I would still reccomend it. One warranty issue, when the diodes in the wattmeter circuit went south, but I was able to repair it thanks to the helpful service dept at MFJ. As a ham who likes to tinker, I appreciate that their warranty is not voided if you try to fix it yourself.
Two points to make for those who need a good balanced line tuner...
First, this is a big box with no antenna switch so you might want to connect it to the "bypass" port of another tuner if you have both coax and ladder lines running to multiple antennas.
Second, you should make a good "cheat sheet" for your antenna by connecting an antenna analyzer (like the MFJ-259) and finding the settings that get you to closest to a 50 ohm impedance and low SWR. You may have to tweak slightly due to weather changes, but you'll always be close (unless the antenna or feedline have been damaged.)
 
WA3DQS Rating: 4/5 Feb 22, 2012 10:44 Send this review to a friend
Very good tuner, minor assembly errors  Time owned: 3 to 6 months
Despite some terrible reviews, I decided that this MFJ-976 balanced line tuner would be a better fit for me than the pricier Palstar unit.
I did a complete "under the hood" inspection before applying TX power, and found a small number of assembly errors which I was able to correct in less than one hour. The gears for the roller inductor turns counter didn't quite mesh (loosen, adjust, and re-tighten the hardware.) A couple of the capacitor mounting screws were only finger-tight (at least I didn't have parts floating around in the box.)
I'm sorry that others have received a product in much worse shape than mine, and I agree that the manual is a mediocre cut-and-paste job based on the cheaper MFJ-974 model. But overall, this is a well-designed, easy to use tuner. The vernier drives on the tuning capacitors are great - much easier to tune than my old MFJ-989B!
I'm using this tuner with a random loop (about 470 feet long, 40 to 80 feet high) fed with ladder line (outdoors) and twinax (indoors.) It took me a little while to find the best match on each band, but now I can preset the tuner based on my "cheat sheet" and get 1.1 to 1 match (or better) from 80 thru 6 meters - not quite as good on 160 but 470 feet is a "short" loop for that band.
Bottom line - If you have the space to put up an all-band, balanced feed antenna (loop, doublet, etc,) you'll get better results with a balanced output tuner that can match a wide range of impedance values as you go between the bands. This tuner is rated for legal limit - in theory the choke balun on the input side should suck up less of your TX power than a toroid balun on the output side, when dealing with the high SWR of a non-resonant antenna.
There's a chance that you might have to take advantage of the MFJ "no matter what" warranty, but there's also a good chance that you won't. Count me as a satisfied MFJ customer.
 
N1CKX Rating: 1/5 Dec 30, 2011 10:29 Send this review to a friend
NOT unless you like building Kits - Works Fine When Repaired  Time owned: 0 to 3 months
Anyone who thinks that Heathkit stopped shipping kits only needs to buy an MFJ-976 Balanced Line Tuner to dispel that notion.
What has occurred is they now partially assemble the kit, place all the parts in an enclosure, throw away the assembly instructions and put MFJ on the Box.

After all, Real Men don’t need road maps, and Real Hams don’t need Assembly Instructions.

My “Kit” arrived in a pristine shipping box with a pronounced “rattle”.
The plastic bag covering the “tuner” contained a half dozen screws and nuts.

Opening the enclosure I found the only thing holding the variable capacitors in place were the control shafts and the heavy gauge wire that connects the caps to the back panel.

There were at least 15 more screws and nuts either finger tight/loose, or backed half way out.
The Split rotor plates on the caps were rubbing on the stator plates, and when the knobs were tuned only the front rotor sections connected to the control shafts turned, the rear rotor sections did not turn.

The two sections of the rotors are “connected” with a cheap piece of phenolic shafting secured to each section with a SINGLE 6-32 set screw. These were not secured.

Next, the rotary contacts consist of the following items.
1 - A flanged copper bushing slipped over a large ring terminal and pressed into a fiber glass end plate.
2 – Two copper washers with a wave washer between them.
In theory the Wave Washer is compressed between the two copper washers bearing against the flanged bushing, providing connection for the rotary sections of the caps.

However, as assembled, the two copper washers and the wave washer on the front/control shaft end were simply riding along loose on the shaft with NO connection at all.

The ring terminals were also floating loosely between the flanges of the bushings and the end plates with at best, very loose intermittent connections.
The “Roller” inductor was of similar construction.

Except instead of two copper washers, there was a strip of thin copper folded back and forth with a hole punched through the folded section to allow the shaft to pass through, and a wave washer was stuffed into one of the folds.
The ring terminal on this bushing was loose also.

The opposite end of the roller inductor had a nylon bushing running against a square copper block that supports the roller shaft.
This square block turned with difficulty against the nylon, and was already beginning to erode the surface.

I removed and completely rebuilt the capacitors ( a time consuming process ) soldering the ring terminal to the flanged bushing, and correctly setting the distance between the end plates so the wave washers were properly compressed and providing a connection.

The Phenolic “coupling” between rotor sections was replaced with a very stiff fiber glass shaft. I also added silver conductive grease to the face of the flanged bushings to provide a better contact surface.
The same treatment was given to the rotary contacts of the roller conductor, and a thrust washer was added to the end where the nylon bushing was.

The inductor now turned smoothly, and had a solid electrical connection.

When it came time to reinstall the components I notice that the shafts did not align (vertically) with the front panel knobs.

The fiberglass end plates are designed to sit flat on the bottom of the chassis thereby aligning the shafts vertically to the front panel.
However the small “L” mounting brackets were holding the fiberglass plates up off the surface by about 1/8 of an inch.

The capacitors and roller inductor do NOT have flex couplings, but instead the caps have a cheap plastic shaft pressed on to a spline on the capacitor shaft.

This plastic piece is about 1 ½ inches long, and the discrepancy in height would have resulted in a serious angular misalignment and ultimate failure of the spline coupling. (This is thin wall plastic and brittle).

I also had to be careful to adjust the Capacitors so they did not have a lot of “drag” when turning to prevent failure of this spline.
Striking a balance between good electrical connection and mechanical drag is crucial here.

I had to slot the mounting holes in the Fiberglass to allow the plates to move down and sit on the chassis and allow the shafts to line up with the panel.

Home free, I thought. Not so easy. The next issue was the plastic shafts on the caps were about ¼ inch too long, and this caused the caps to miss the mounting holes on the bottom of the chassis by a like amount.

This, coincidentally, was about the same amount of gap that was between the copper washers and the wave washer when I opened the cabinet.
During assembly they had moved the shaft back in the caps to allow the mounting holes to align, resulting in a total lack of electrical connection between the washers.

Cutting the shafts was risky, so I instead slotted the mounting holes in the chassis which allowed the caps to slip into place.

With four evenings of about 4 hours each I now have a decent balanced tuner.
One of the other reviewers claims a measured insertion loss of only a couple of tenths of a dB. Pretty impressive compared to a standard tuner with balun.

Why you may ask did I even bother. I have a dozen pieces of MFJ gear and pretty much knew what to expect. Some assembly or repair is almost always needed.

However I needed/wanted a true balanced tuner, and rolling my own would have actually cost more just to purchase the caps and roller inductor.
Not to mention obtaining a cabinet, knobs, SWR meter etc. etc.

So in effect I purchased a “Kit” and rolled my own. I cannot however recommend this unit to anyone unless you have a lot of experience building transmitting caps and have access to a machine shop and have a well filled tool box.

Should we get into the manual? Why not? I don’t mind they run these off on a photo copy machine as needed. Printing costs are high.

However, this one is a compellation of “cut and paste” from various sources, several of with are obviously not for this particular tuner.
They keep talking about switch settings related to the alphabet. (From their low power balanced tuner).

They say “Do Not Change Inductance When Transmitting” because of the switch.
However, with a roller inductor (correctly assembled) this is not the case and it is perfectly acceptable to adjust the inductor when tuning.

This is going to confuse any one not versed in these tuners.
Not to mention the tuning information and charts provide all have the information arranged as “ Antenna/Inductor/Transmitter “ while the front panel is layout is “ Transmitter/Inductor/Antenna. “

Again, this renders the tuning charts confusing for anyone not familiar with using a tuner.

MFJ is celebrating their 40th Anniversary. Congratulations, but I fear you won’t be around to see 50 unless you get your act together. And that would be a shame.

I love looking through you catalog. But usually use it for a reference to shop at other vendors first because of quality issues.




 
NB3K Rating: 5/5 Sep 10, 2011 14:41 Send this review to a friend
MFJ Quality Control needs RE-DOING  Time owned: 6 to 12 months
Besides having to complete the tuning circuit (I had to link the circuit so it would tune who ever built it forgot to make sure it was finished) I find nothing wrong with the product.

This thing tunes my 80m di-pole fed with 450 ohm ladder line from 160-6m. I am very happy with the unit. BUT MFJ HAS TO GET THEIR S!$* IN ORDER!
 
WB5UAA Rating: 5/5 May 3, 2011 07:25 Send this review to a friend
Received lemon, got a good one  Time owned: 0 to 3 months
KJ5XF, looks like the one you sent back to the company who sold it to you resold it to me.

I contacted MFJ, and thanks to Mr. Bob Ellis, I mailed it to him in Starkville, MS and he mailed the next new one off the assembly line back to me.

Maybe MFJ could inspect those roller inductors a little more closely when they receive them from whomever makes them and sells them to MFJ.

300 foot dipole with bent legs, up 30 feet, fed with 55 feet of home brew open wire 600 ohm ladder line and this tuner loads up anywhere from 160 to 6, and with 1KW into it, it works fine. This is the last tuner I'll ever need. I'm happy.

I've seen a lot of bad reviews in here regarding MFJ's quality control. Given the number of products they produce and the number of employees they have, it's no wonder they have some lemons slip through. Over the past two decades, I've bought countless MFJ products and this is only the second time I've bought one of their products (through a vendor) that turned out to be a lemon. Both times MFJ has replaced it with out any other questions other than "what's wrong with it?"

Speed, price, quality--unless price is not a concern, pick two. MFJ's speed and price are good. Where they lack in quality is made up by their "No Matter What" warranty. I'm still one of their happy customers.
 
KJ5XF Rating: 0/5 Apr 8, 2011 16:52 Send this review to a friend
Poor quality control!  Time owned: 0 to 3 months
I have had several MFJ products over the years and they all have worked fine. This tuner is the exception... The first thing I noticed were sounds of something rattling around when I picked up the box. So I took the lid off and looked inside. Sure enough, there were 2 loose screws!! (Strike one!!)

I also noticed that the plastic linkage that joins the antenna vernier drive to the capacitor was not even physically connected...
(Strike two!!!).

After finding a small allen wrench, I connected the linkage between the vernier drive and the cap. I took one last look inside and all looked OK. I then proceeded to find the tuner knob positions for the frequencies were I typically operate using an MFJ SWR analyzer. I noticed that the roller inductor crank on the MFJ-976 didn't feel smooth at all when I was turning it. That's when I realized that the roller inductor wasn't making a good connection. I could finally tune on the frequencies that I operate on (mainly CW), but if I moved the inductor crank just slightly in either direction, the SWR would be all over the place. You would expect a linear type of SWR change when moving away from the desired setting... Nope, not with this 976!
(Strike three!!)

Very unfortunate, since after I took care of the first two issues I was looking forward to actually
keeping the tuner. However, the problem with the roller inductor was just too much.

I boxed it up today and sent it back to the company that sold it to me...
 
KA1YUW Rating: 5/5 Apr 21, 2010 20:52 Send this review to a friend
Great Tuner  Time owned: more than 12 months
I bought mine on ebay a few years ago. I get a 1:1 swr any where from 160-10 meters. I use the cobra antenna which is 140' long fed with 450 ohm latter line. A great tuner for the price.
 
W5VIN Rating: 5/5 Apr 4, 2006 17:21 Send this review to a friend
A Keeper  Time owned: 0 to 3 months
I purchased an MFJ 976 Balanced line tuner a couple of weeks ago and so far am pleased. The tuning action is very smooth. Using an IFR-1500 with tracking generator the measured loss in receive on 75 meters was about 0.3 dbm. My MFJ 986 differential "T" measured 1.3 dbm loss on the same frequency. It handled 1800 watts in tune position. The components must be adequately sized or there sure is a lot of empty space inside as it is not a small box. It dwarfs the MFJ Differential "T".
 


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