| W4HM |
Rating:      |
2021-06-02 | |
| Great Low Power Antenna Tuner |
Time Owned: more than 12 months. |
I own two of these balanced antenna tuners. I find them to have a larger tuning range than the Palstar BT-1500A.
Using 450 ohm window line the tuners match any HF band to any HF antenna.
73,
Thomas F. Giella W4HM |
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| KD7MW |
Rating:     |
2021-05-31 | |
| Good balanced-line tuner, insensitive SWR meter |
Time Owned: 3 to 6 months. |
The MFJ 974B is a good 100 watt-class balanced line tuner built to a low price point. It has a couple of quirks, but they can be worked around. I have two balanced line-fed antennas, a 40 foot vertical dipole and a 92 foot inverted vee. The 974B matches the vertical on 40-6m and the vee on 80-6m, with no arcing and no "RF in the shack."
I bought the 974B on close-out from Ham Radio Outlet. The current 974H version is the same, but adds an additional coil and switch to cover 160 meters. When I received my unit, I checked inside for loose screws, connections or solder blobs. The screws were fine. There were a few bits of solder stuck to the chassis, which I loosened and removed. The coil taps were properly connected to the 12-position switch. The four variable capacitors are supported by a bracket which flexes slightly as the caps are tuned. Each pair of capacitors is synchronized by a pair of large plastic gears. They turn a little roughly in places, but they work well. After working inside the unit, I had to flex the chassis slightly to get all the cover fastening screws to match up with their holes. In all, the construction is not "built like a tank," but quite functional.
It's best to tune any tuner with low power. And that leads us to this tuner's weak point. As supplied, my 974B's Reflected power meter worked correctly at the high-power setting, but was horribly insensitive at the low-power setting. During tune-up with 10-20 watts, the Reflected power meter would not budge off zero until my radio's SWR meter showed 2:1 or over. I verified this with another external SWR meter. In other words, the 974B would show a perfect match when actually, the SWR could be anywhere between 1:1 and 2:1. Not very useful.
There are meter sensitivity adjustment pots inside the tuner. I turned the low power Reflected adjustment pot to maximum, but it had no effect. So I returned the unit to HRO, and they sent me another with no hassle (thanks, HRO!). And... the second unit did the same thing!
After further experimenting, I found that the low power Forward and Reflected sensitivity adjustments are interdependent. The more sensitive the Forward meter is, the less sensitive the Reflected meter is. When the Forward adjustment is set so that the Forward meter displays accurately, the Reflected meter doesn't detect any current until the SWR is already unnaceptable. I turned the Forward sensitivity to minimum and the Reflected sensitivity to maximum. Now the Reflected meter, while still less sensitive than it should be, gives a useful null when tuning at low power. The tradeoff is that the Forward meter only shows 1-2 watts out of 10-20, but that's not important to me.
The meter issue occurred on two units manufactured in two different years. Make of that what you will. I wrote to MFJ about it, but to date have received no explanation or fix. I'm keeping it anyway. Other true balanced line tuners are much more expensive, and the 974B does the job.
For an excellent discussion of antenna tuners in general, and why balanced tuners are preferable with balanced line, see DJ0IP's excellent Web site, here: https://www.dj0ip.de/antenna-matchboxes/
The page on Symmetrical Matchboxes describes the 974B's circuit, and several others.
Remember that with balanced line and multi-band antennas, impedance and reactance at the tuner varies drastically at different line lengths. Some lengths at some frequencies can have impedances as low as a few ohms or as high as a few thousand. Either extreme is not good for your tuner, and can lead to "touchy" tuning, high loss, arcing, or burned out switch contacts. If you have trouble tuning a particular band, don't blame your tuner. Add about 1/8 wavelength of line at the problem band, and you may find things are much better. Trial and error often works. Using an antenna analyzer and a 1:1 balun to "sweep" the bands of interest is even better. It will tell you where the impedance peaks and minimums are. Add some line and check again. Aim for between 50 and a few hundred ohms in your favorite bands, and you'll probably be very happy. Finally, NEVER hot switch the inductance control. Turn off the transmitter before moving the switch. The tuner you save may be your own!
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| KC7WEU |
Rating:      |
2021-04-02 | |
| Great tuner |
Time Owned: 3 to 6 months. |
| Great idea to put the balun on the input side. I am a big fan of balanced feed lines, and loved my small Match Box, but wanted 160. I was very disappointed in my ability to tune my 160 inverted V satisfactorily on any band with this tuner. After much very close inspection, found two of the coil taps shorted to the adjacent turn. More MFJ poor quality! After repairing that problem, am very happy with the tuner. |
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| KZ4IM |
Rating:      |
2019-07-31 | |
| Works great! |
Time Owned: more than 12 months. |
I am able to tune my antenna with a SWR of 1:1 on all bands 80-6m. I can also tune 1:1 on 160m, but the antenna has no range (maybe 30 miles). I can reach all of NA, SA and Europe with FT8 and 20-30 watts from Atlanta, GA. I recently had a nighttime QSO with New Zealand on 80m.
My antenna is a center fed attic dipole bent into a near 20' x 27' rectangle. I am feeding the antenna using the center conductors of two 75 ohm TV coaxes with the shields connected and grounded. This gives me a balanced feedline that avoids the effects of the metal ducting and HVAC.
My 974's build quality seems fine. |
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| N7NC |
Rating:      |
2019-05-10 | |
| smart design |
Time Owned: more than 12 months. |
| After reading Walt Maxwell's "Reflections", I noticed MFJ had come out with the 974 balanced tuner with the balun, a choke balun, on the input side. As this follows Maxwell's recommendation, I bought the tuner and am very satisfied. Also it seems to be good to at least 400 watts. Palstar's Balanced Tuner, also uses a choke balun on the input side and would love to have theirs but is $795. |
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| M1EAR |
Rating:      |
2013-11-11 | |
| Amazing but it's still going |
Time Owned: more than 12 months. |
| Well, it is a MFJ! but hey mine has been a sturdy home base unit as well as being transported over the Akamas Peninsular here in Cyprus for over 3 years and has worked well with various antennas including "bits of long wire" and as long as you keep the key down power below 150w or better still around 100w it's a workhorse without complaint. Wouldn't dream of using it over 150w, I suspect a flash over would be the result. Must say inside my 974H it's well constructed (can't believe I'm saying that about a MFJ product) but in this case it's true. No regrets on my purchase. Would I buy another? Not before checking it's construction first, if it's built as good as mine, Yes I would.... |
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| LB6BG |
Rating:      |
2013-09-12 | |
| Excellent performance |
Time Owned: more than 12 months. |
Well, what I have got is the MFJ-974 (without 160 m), I have been using it almost every day for about 2 years. And, believe it or not, I have even bought a second one for prtable use.
I am not very exited for MFJ-tuners because of generally poor craftmanship, but both tuners arrived without any soldering problems or loose screws. I am using a 2x18 m doublet, that is the space I have got. With other tuners, for example Palstar symm tuner, I had to fiddle around with the length of the feeder to achieve tuning on all bands, but the 974 does the job regardless feeder length. Also for different portable set-ups, I never had a problem with the tuning. I have, however, never tried to tune a coax fed antenna. With my 90 watts, the tuner does a great job on all types of symmetrically fed antennas. I have even been using this tuner with open feeder to elevated verticals of random length - with good signal reports. |
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| G4BXD |
Rating:  |
2013-08-31 | |
| fried switch |
Time Owned: 6 to 12 months. |
After about 9 month of use, at no more than 100w max, one of the switch contacts on the main coil flashed over and burnt the switch paxolin. I have tried cleaning it but had to resort to cutting the wire from the coil to the switch on that contact. Frankly, the switch looks, and obviously is, far too small for use. It should have been a ceramic switch at least. Not really great value for money I feel.
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Earlier 2-star review posted by G4BXD on 2012-12-24
Just bought 974HB to replace old KW-Z match. Frankly, looking inside its a rather poorly made thing. Plastic gears, not lined up, flexing mounting panel for tuning caps which moves as you rotate controls. No slo-mo on tuning or i/p caps, quite small switch for coil taps. Cap spacing looks far too close to run 300W. With 135ft doublet, 450 ohm line, the KW matched it easily. 974HB will not tune high end of 80, tunes low end just, other bands all very jumpy. Considering the cost of the thing I cannot really say its value for money. I shall be going back to my trusty KW unit. |
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| K7TP |
Rating:      |
2012-07-31 | |
| Does the job very well! |
Time Owned: more than 12 months. |
I have used this impedance matcher (they're not antenna tuners, but you knew that) for about ten years. It never fails to give me a good impedance match on any of the hf bands using a 112' flattop antenna fed with 450 ohm window line.
I never run more than 100 watts and usually run below twenty. That makes the low-power switch on the meter very useful since in the low position it tops out at slightly more than twenty watts. The readings of the meter in either position compare with my Bird and other meters.
I've worked 200 countries with this arrangement and twenty watts or less.
I don't try to feed unbalanced lines with this even though the product information says one could.
I'm very pleased with this product. |
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| REMOVED_VK4NR |
Rating:      |
2010-09-13 | |
| Good Value |
Time Owned: 6 to 12 months. |
I’m the sort of guy who likes to run only 100 watts and use simple wire antennas.
I had been using an MFJ-949e for many years but liked the idea behind the 974b with a 1:1 choke balun on the input.
Beacause of the reports of MFJ’s variable build quality I took the covers off, when first getting the unit, and took a look inside. All was OK with good solder joints, no missing or loose screws etc.
In fact I thought it looked surprisingly good!
I use it on my trusty 80” centre fed doublet, fed with 450 ohm ladderline, where it tunes all bands 80 through to 6 metres with ease.
Is it any better than the 949e? It’s hard to tell but I am sure it must be more efficient than the 949e when working into lowish impedances.
I’m very pleased with the tuner and the 949e has now been relegated to back-up status.
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