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Reviews Categories | Antennas: HF: Vertical, Wire, Loop | MFJ-1786 Super Hi-Q Loop Help


Reviews Summary for MFJ-1786 Super Hi-Q Loop
MFJ-1786 Super Hi-Q Loop Reviews: 47 Average rating: 4.6/5 MSRP: $379.95
Description: High Efficiency 10-30 MHz Continuous Coverage Magnetic Loop
Product is in production.
More info: http://www.mfjenterprises.com/Product.php?productid=MFJ-1786
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You can write your own review of the MFJ-1786 Super Hi-Q Loop.

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K1CM Rating: 5/5 Jun 17, 2012 07:45 Send this review to a friend
MFJ-1786 - excellent  Time owned: 6 to 12 months
I bought an MFJ-1786 (30M to 10M) Super Hi-Q Loop Antenna about a year ago and hung it vertically in my attic, which put the bottom of the loop at about 28 feet above ground. The loop is suspended from the ridgepole with twine. It has worked much better than I expected it would.
I had thought that loops were kind of gimmicky, but this one changed my mind. After tuning the antenna several times, I was able to get very close to minimum SWR just by listening to and peaking the noise on the frequency (hint: turn off the noise blanker while tuning). The Hi-Q of the loops means that you will have to tweak the tuning when you move more than a few kHz.
I operate mostly QRP c.w., and I have found the 1786 to be every bit as productive as dipoles (30M & 20M) at about the same height, and the loop is much quieter. Loops do, however, have narrow, deep nulls along their axes. I had thought about rigging up a rotating system using strings from the shack, on the floor below the attic, to move the null around. But I decided to get another loop (an MFJ-1788, which covers 40M to 15M) and mount it at a 90 degree angle to the first loop. They are about 15 feet apart. Depending on the direction of the incoming signal, switching between loops (on 30M to 15M) can make the difference between just barely hearing a weak signal and being able to copy it.
As to the quality of the units, I can only say that they have worked flawlessly. I have not taken the covers off the control boxes or the loops, but the units look well-built from what I can see. Both of the loops came with control boxes marked “MFJ-1786.” They must have run out of 1788 boxes.
They both exhibit one minor quirk that I haven’t figured out yet: If they are shut off and turned on again sometime later, they will have drifted slightly, but it takes just a couple of taps on the Fine Tune buttons to retune them.
Read the manual thoroughly, and understand it completely, before using the loops. I recommend these loops to anyone who cannot install full-sized outdoor antennas at their optimum heights.
 
N0YXE Rating: 5/5 May 25, 2012 11:11 Send this review to a friend
BABY BROTHER  Time owned: 0 to 3 months
I have just purchased the MFJ 1780 mini box loop for inclusion in my attic, next to the Alpha Delta DX-EE inverted dipole. The 1786 was fun and worked well. But, I received a court summons from my homes associatiion to remove all stealth antennas. My attic is protected by my middle aged buddies, Mr. Sig and Mr. Glock. Both being 45. You would not believe the ransom note that the hoa and their asshole attorney held me up for. If you would like to see a copy of the summons and the ransom note, I will send them to you. Also, I will send a good picture of the loop and the mini controls as it appears in my shack. An on the air review will follow soon: WRITE TO ME AT:
terryspaceship@yahoo.com
 
N6MV Rating: 5/5 Feb 20, 2012 20:51 Send this review to a friend
Only 3 ft in Diameter and 3 ft Off the Ground !  Time owned: 0 to 3 months
Relocated to a development with CC&R's, so left behind the 55 ft Tower and 3 El. Yagi- that I used for 32 years and went about looking at everything possible to use for an HF Antenna, viz. loading the rain gutters, using a stealthy flagpole, as well as using a small Hi Q Loop.

My MFJ 1786 Loop has been in use for only 2 days now, located only 3 ft off the ground,and I was very pleasantly surprised at how well this loop works on 20, 15 and 10 meters, for I was able to hear and speak with others on the East Coast, in Europe, Japan and South America - with ease, running 150 watts. Tuning is not that difficult once you get the hang of it, using the Auto Tune and Fine tune buttons, while looking at forward and reflected power.

Recommend buying an MFJ 1786, and once you see how MFJ built the loop and the controller ,you can then go forward with building one for 40 and 80 meters, using copper tubing for lower resistive losses, along with a vacuum variable capacitor so you can run more than 150 watts.

Best Article on the web - with many photos and references - including an Excel Spread Sheet to design your own Hi Q Loop is located at:

http://www.aa5tb.com/loop.html

No question about it, the MFJ 1786 Hi Q Loop is an excellent antenna for those who have restrictive CC&R's and I have no regrets in purchasing it- whatsoever - for it works great !

And, if you would like to see what an Exposed MFJ 1788 Loop looks like- one can be seen at:

http://www.g1zrn.net/1788.htm

Upstream,the challenge is to build a servo- stepping controller that automatically tunes the loop as one changes frequency - for this is the only negative of using a Hi Q Loop.

73's
 
K2NCC Rating: 5/5 Sep 7, 2011 01:37 Send this review to a friend
more bands for the buck  Time owned: 0 to 3 months
It may take a month or two to receive this antenna. I used the extra waiting time reading the 1786 manual. There are used MFJ loops cheaper, but I recommend you pay the extra 100 bucks and get support with it.

Inspect inside the box before walking out the door or accepting delivery. "Figure 8” shaped antennas have been reported due to mishandling.

It's delivered in a big box, so it won't fit in a compact sedan if you're going down to HRO to get it. It fit in my Nissan Sentra after I removed it from the packing. But consider the possible need to return/ship the antenna before discarding the box. Don’t bang it up going down the road.

If you’re after DX, over 20 feet up and horizontal is the way you’ll want to install it.

Check all the bands you can work before nailing it down. One band might be fine while another is useless. I’ve had zero problems on any band so far.

Installs in less than an hour if you’re prepared.

Don’t forget to disconnect EVERYTHING between the control box and the antenna. Well, except the coax of course! No low-pass filter, no lightening suppression, no balun... nada.

I did pound in a dedicated isolated ground to strap to the braid of where the coax enters the house. I use real LMR400, which I recommend. Low-loss line is best with this antenna. You’ll also need a short run of coax to bridge the radio to the 1786 control head. Keep it short.

BE SURE to watch your SWR meter or the control box as you TX, since small adjustment are sometimes necessary. If your tuned antenna suddenly shoots up in SWR, tap the slow tune up or down once or twice and you're back in tolerance.

Tuning is really narrow. Nearly any frequency change will require a re-tune of the antenna. The mag-loop can be tuned by ear with eyes on the meter, otherwise, use a solid, stable tone when tuning the control box. Whistling won’t do it, so use a key or your radio’s tune tone.

Not that it’s a high noise level at the QTH, but I found the loop just as noisy as my previous antenna; a 20M homebrew half-wave dipole. Both measure a noise level around 3-5db on 20M mid-day. However, considering where I had the dipole compared to the loop, I wouldn't be surprised if I received some gain from loop.

SWR was below 1.5:1 on all six (really *7*) bands. Everything does as expected. Easy to tune, although frequently required.

I seldom give a day-one review, but my first impression is a solid 5. Not enough bad things to lose a star. Although I’m not confident this is a 10 or 20-year antenna. Another reason to buy new.

There’s enough good that I’d recommend the upgrade to anyone with a compromised antenna or restrictive QTH.
 
ON5UN Rating: 5/5 Sep 6, 2011 01:18 Send this review to a friend
Amazing antenna for restricted space  Time owned: 0 to 3 months
I ordered the MFJ-1786 from Classic International in Roermond ( Netherlands) Got it well packed 3 days later. I packed it out immediately and found that the mains adapter for the remote control box was a USA version 110VAC, a simple mail to Classic International solved this and I got a European 240VAC one 2 days later. The finishing of the antenna is not the best and I expected that from MFJ, but a little filing solved the not perfect alignment of the mounting clamps holes. I have tested the loop at a height of 1.5 meters above ground on 29 August and compared it with my ground mounted Hutsler 6BTV with 30 radials .( Hutsler 6BTV has no WARC bands)

In general the Hutsler 6BTV has a noticeable better result, however the loop gave an unexpected result. I made that day 29 QSO with the mag loop in JT65 mode and this resulted in 15 QSO with USA, 3 with JA, 5R8UO and ZP9EH, the other QSO were all inside Europe. Pretty amazing! All with 30 Watt.
Tuning with the control box is easy ( and very sharp) Very good SWR on all bands, except 18 MHz where I cannot get it better than 1.8

Advantage is that the antenna can work on 18 and 24 MHz. If you have only a small space, a magnetic loop is the antenna to consider, but do not expect it will perform like a beam or a larger well placed antenna. And Classic International service was also perfect.
 
KJ4EBE Rating: 5/5 Jul 1, 2011 19:08 Send this review to a friend
Great antenna, but...  Time owned: 0 to 3 months
Well... this is a great antenna. Easy to tune, great when receiving and very good when transmitting. It is incredible how such small antenna can perform that well. This is not just a highly compromise antenna for small or restricted places, this antenna really give you a very acceptable performance even at only 10 feet over the ground. Obviously it is not a bean at 100 feet but this Loop can compare to any multiband vertical.

Now the "but" part... the mounting clamps holes... well, not a perfect matching with the antenna mounting holes. So I had to buy a Dremel and work out the mounting clamps holes until they fitted with the antenna holes. Not a big deal but I had to spend $40 on a Dremel.

Like antenna the MFJ-1786 is a 5, but the quality control needs improvement. I gave a rating of 5 because, after all, the antenna is performing great.

I recommend this antenna if you want a great performance on a small package.

If you have any particular question email me and I will be happy helping you. My email on QRZ.com
 
CT1DRB Rating: 5/5 Jun 5, 2011 06:32 Send this review to a friend
Perfect antenna for my situation.  Time owned: 3 to 6 months
Hello all,

since some time I have this antenna, knowing that till end of my life, since I still live in this building (it is very difficult to buy a new home up to now in Portugal), I will not have any kind of antenna on building for sure for ever.

This antenna is my gate to HF and up to now is working fine, of course I use it inside my home, signals are not that strong, but I am able to work some interesting DX's like VP5/W5CW or PZ5RA.

Best 73 to all.

 
5B4AIY Rating: 3/5 Oct 28, 2010 01:30 Send this review to a friend
An interesting compact antenna let down by poor quality control  Time owned: 3 to 6 months
I purchased the MFJ-1786X loop antenna because I have no room to mount a decent tower and beam. The antenna was ordered from a UK supplier, and it took months to arrive. I had originally ordered the MFJ-1788X antenna which covers from 40-15 metres, but because of a mix-up, I had to settle for the MFJ-1786 version, which covers 10 - 30 MHz. The antenna arrived well packed, but upon examination, it was incomplete. One of the threaded mounting inserts was missing as were two of the mounting bolts. As this item is of US manufacture, all its threads were SAE rather than metric, and thus replacement bolts and inserts are unobtainable here in Cyprus. To be fair, MFJ sent a set of bolts and inserts after I wrote and explained problem, but it did take some time.

In the meantime, I removed the covers and examined the internal construction, and overall fit and finish. The antenna is poorly finished, and looks more like a pre-production lash-up rather than a finished item. The quality of the soldered joints left a great deal to be desired, particularly those connecting the drive cable to the motor. The tuning capacitor's mounting bolts were loose, and the printed circuit upon which is mounted the RF isolation networks to the drive motor looks as if it was made mirror-image, the components being soldered to the track side of the board rather than through the board. At the RF input section, it was clear that the original design called for the small PC board to be mounted using 4 pillars - only 3 are present because the screw for the fourth pillar would sever a track if it was used. When I first powered up my antenna, I could not tune anywhere near the highest frequewncy. On the capacitor's shaft is mounted an 'L' bracket which trips the end-of-range micro-switches. This bracket was fouling a round-headed screw on the printed circuit panel. Shouldn't this screw be replaced with a countersunk headed variety to avoid this? I had to use a pair of pliers to bend the bracket to clear the head of this screw. The SO-239 chasis mount RF input socket is secured with only 2 screws rather than 4. The 4-piece plastic cover is a poor fit on the assembly, and is not weatherproof or insect proof. Here in Cyprus rain is not really an issue, but the bugs really do like to make nests inside these things. Considering that this item has now been manufactured for more than 10 years, is it really too much to ask that a production engineer review the current manufacture and fix these problems?

In contrast, the printed wiring assembly in the main control unit is very well made, using surface mount components. Sadly, it is mounted in a cheap bent steel box whose cover is secured with sheet metal screws. Considering that inside this box is a battery holder to allow operation from AA batteries, how long will it be before these fixings fail as they are not intended for repeated removal and replacement. Interestingly, when I measured the current consumption, even with the motor being driven at its fast rate, the consumption was only about 20 mA. If the meter illumination lamp is turned on, this consumes more power than the entire control unit and motor combined! Again, as MFJ offer a high-intensity LED replacement illumination for this particular meter, why have they not seen fit to equip all current production controllers with this to reduce the drain on the battery?

The antenna is very sensitive to the presence of objects within a radius of a few metres. I experimented with the antenna in a number of locations in the garden, and found it very difficult to achieve resonance or low VSWR if there was any metallic structure or other objects anywhere near the antenna. However, once it was mounted a few metres off the ground and clear of the house its VSWR improved. It still required a fair amount of "tweaking" of the coupling loop, but eventually I could obtain a steep resonance curve over the entire frequency range, as well as a VSWR that was less than 1.2:1 at the lowest frequencies, and no more than 1.3:1 at the highest. These measurements were made using a RigExpert AA-230Pro antenna analyzer. I found that squeezing the coupling loop into a more vertical elliptical shape narrowed the bandwidth of the resonance point and tended to improve VSWR, whilst broadening it to a more circular shape increased the coupling, widening the bandwidth, but tending to worsen the VSWR. The shape of the loop is a delicate compromise between VSWR, coupling, and bandwidth.

The antenna has now been in operation for about 4 months. It takes a little practice to learn how to use the tuning arrangements, but once mastered it is quite easy. In my case, setting my Kenwood TS-2000 to its lowest output power - 5 watts - then selecting CW mode and pressing the SEND button provides more than enough drive for the auto-band tuning to work. The manufacturer's say that there will be a beep from the unit when it stops, in may case this beep is virtually inaudible, but at least the LEDs extinguish, and the motor stops. Because there is a fair amount of inertia as well as backlash in the simple reduction gearbox used, the motor usually over-runs the desired VSWR null point, but a few deft touches of the slow buttons quickly brings the unit into tune. After a while it becaomes almost automatic.

As far as contacts, I can usually work almost anything I can hear within a radius of about 2,000 - 3,000 kms on 20 metres. The antenna is quite quiet, but in fairness, my QTH is not noisy anyway. Obviously this antenna is not going to put down a signal comparable to a multi-element beam on a tower, but considering its diminutive dimensions I am quite surprised at how well it performs.

In summary, on the plus side it certainly works, and for those requiring a compact antenna, this might well be the answer. On the negative side, its construction, fit and finish leaves something to be desired especially considering its price. On an operational negative side, this is not an antenna that will permit rapid frequency changes, and demands a certain additional consideration from its user to carefully tune it. Because it is a very high 'Q' tuned circuit there will be very large RF voltages present on the tuning capacitor, do not exceed the manufacturer's power ratings otherwise a RF arc is likely with severe damage to both the antenna, as well as possibly the transmitter as a result of the violent mismatch that would result.

 
MW0CVW Rating: 5/5 Jul 25, 2010 13:54 Send this review to a friend
Very Good  Time owned: 6 to 12 months
My first review on the loop commented on the poor construction but my comments have now changed.

I finally gave the Loop a second chance and re-ordered a second unit.

I installed the loop at 5 meters above ground on a Yaesu GR250 rotator via 20 meters of Westflex 103 coax cable.

The loop tuned up fine on all bands from 10mhz to 30Mhz with now problems at all.

Contacts into south America,Europe,with no more than 50Watts on SSB and Psk31.

One little problem I have suffered from is Bugs and insects getting into the loop via the holes in the plastic ABS cover.

The problem showed when running more than 50Watts of rf the VSWR would be very unstable.

I discussed this problem with MFJ who advised me to seal the gaps with a Window Silicon sealent.

I must admit the loop works well for anyone with antenna restrictions or a small back garden like me.

 
WB0FDJ Rating: 5/5 Jun 20, 2010 17:06 Send this review to a friend
Better than you'd think!!  Time owned: more than 12 months
I've had this antenna over two years now, having acquired it with the plan (still not entirely abandoned) to put it outside on a mast. Since being purchased it sits in a second story unused room. Had to move it around a bit to find the "sweet spot" where the SWR will be acceptable. There it is: an indoor antenna that, to look at it, shouldn't do much. My subjective experience is that it is about as effective as a well made dipole. I know thats not "scientific" but it give you some idea of what to expect.

My on the air experience with this has been amazing. I had it working a few minutes after it came out of the box. Over the years made a lot of QRP contacts on it on all bands. Once I was using the wattmeter to look at the output on my newly built Small Wonder 20 meter QRP rig (2 watts) & worked both coasts with good reports in a couple of minutes. Now its my 30 meter ant for psk31 which I am listening to while writing this review.

I see this as a specialty antenna. Effective over a wide range of frequencies, one coax, easy to stash away if you need it indoors. If I ever lived in an apartment with a balcony, this would be IT. A good product, has given me no difficulty and allowed me to make contacts when I didnt have other antennas. Still using it.
 
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