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Reviews Categories | Antennas: HF: Vertical, Wire, Loop | MFJ-1788 Super Hi-Q Loop Help


Reviews Summary for MFJ-1788 Super Hi-Q Loop
MFJ-1788 Super Hi-Q Loop Reviews: 52 Average rating: 4.0/5 MSRP: $429.95
Description: High Efficiency 7-21.5 MHz Continuous Coverage Magnetic Loop
Product is in production.
More info: http://www.mfjenterprises.com/products.php?prodid=MFJ-1788
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You can write your own review of the MFJ-1788 Super Hi-Q Loop.

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VE3CUS Rating: 3/5 Dec 14, 2015 18:43 Send this review to a friend
Works great one fixed  Time owned: 0 to 3 months
Just bought one of these as I have no space in the yard. The antenna works great....but, as many have noted MFJ has quality control issues.
I noticed that the antenna worked great on 30 and 40, but when I tried to use it on 20, 17 and 15, it would tune fine on low power, but as soon as I went to 50 watts, the swr started to bounce around. After testing the feedline, I finally took it down and opened it up. Firstly, although heavily made, the tuning capacitor loOKs more home brew than a price ion machined component. The plates were misaligned, and I suspect the shaft was slightly off centre. The result was that at certain points, on high power, there was some arcing. After playing with the cap a bit, I noticed that at certain points the plates whefree shorting, the first clue being that on 17 I was getting no receive peak whatsoever.

An hour with a wrench and screwdriver, and I had the plates bent so they wouldn't touch the locknut tightened and the Microswitch lever aligned. All of this is easy to understand if you know a bit of theory, but it could be a rreal problem for a new ham with little practical rf experience. Maybe they just don't make capacitors like they used to but I was disappointed with the machinin gand tolerances. That being said, operationally the antenna now performs extremely well. For me, it wasn't worth the time or effort to send it back k, when I could repair it myself but others may wish to do so if they have a similar problem
 
K3JLS Rating: 5/5 Mar 11, 2015 20:52 Send this review to a friend
Great - But Concerned About Near Field Exposure  Time owned: 6 to 12 months
Hello all.

I bought on of these loops last year and mounted up in the attic. It works very well. However, we are planning to move into a retirement apartment later this year, and I want to be sure that this antenna will not cause any health problems for me, my wife or for my neighbors.

I spoke with MFJ about my concerns today, and was told that (and I quote) 'a 100 watt light bulb probably has more radiation'. The technical folks know of no problems with RF exposure provided the loop is kept at a 'safe distance' (???), and not touched while transmitting.

So, I'm going to write to Martin Jue from MFJ about my concerns. I would think / hope that the manufacturer of any magnetic loop antenna would have conducted the necessary empirical technical tests (or, at the very least EZNEC) to measure (estimate) the near / far field radiation and thereby inform amateurs as to the results of the same in the context of the FCC's RF Exposure Guidelines.

Just to be on the safe side, I'll send a certified copy of this letter to the appropriate FCC official responsible for RF Safety.

73's - Joe K3JLS
 
W3NRL Rating: 5/5 Jan 6, 2015 11:41 Send this review to a friend
Totaly surprize.  Time owned: 0 to 3 months
I bought one of the loop from gentleman second hand i was told it was a 1786 10-30 meters but i was having problems tuning 10 & 12 meters so i decided to tune 40 wow ok now thats awesome. I have 1788 instead, since putting the antenna up i have made several contact my best contact was to VU3WIJ and with 57 and also made contacts into Russia and other contact in that rtegion with nothing less then 55 also checked in to several nets as well and i am sold on the loop system that i planning on making one to take on vacation to OBX. lots fun!!!!
 
WA4GQG Rating: 0/5 Dec 7, 2014 07:14 Send this review to a friend
Worthless junk...  Time owned: 6 to 12 months
I would advise that you stay AWAY from this (or ANY other) MFJ product. I stupidly bought one of these PsOS about 15 years ago; when I sold it, I clearly explained I considered it junk...even at less than half price, I felt ashamed to sell this #$%^ to a fellow amateur.
 
AA7FY Rating: 5/5 Dec 2, 2014 13:01 Send this review to a friend
Back on the Air!  Time owned: 0 to 3 months
Thanks to the eHam reviews I am able to give this antenna a 5. I took the advice and opened it up as soon as it was out of the box; glad I did. Capacitor set screw to the motor was completely loose. I carefully aligned the plates using a caliper to measure exact spacing and then tightened it all up. Then worked the SWR from 7-21 by adjusting the internal loop. On the air with it on the shack floor have been impressive! Why is it there you ask, well I too had issues with the mounting brackets and having new ones made, then it will head out side with a small end feed to give me full run of the HF bands! WAHOO! Just keep the HOA off my back and I am a happy ham!
 
G0LUH Rating: 5/5 Nov 5, 2014 05:48 Send this review to a friend
Well worth the wait and time  Time owned: 6 to 12 months
Hi I have been out of radio for 20 years and had removed my antennas R7 and G5RV plus VHF for house repairs, I needed something simple, also having just retired I am not able to jump around the roof like a rabbit or climb ladders like a monkey, so in April 2014 I brought the 1788X from ML and Sons UK, very good service and advice as ever. Packaging very sturdy,good quality material, assmbly and instructions very easy,location loft 8 meters high, vertical mounting.
Having been used to having exact SWR or very quick adjustments with a ATU, first experiences in tuning the 1788X was where I discoverd you first need the patience of Job, for you non belivers its where you dont swear,throw you smarties out of the pram,chuck your tools in the air, curse your luck or get violent I think you get the idea.If it dont work, walk away and again and again, then all of a sudden you you get a contact and once you learn the quick and easy way of tuning, ok yes more than 3 or 4 Khz and its retune,pain time ok,well after 6 months now all my contacts have been 59, one was 56 one was 57 distances of 5000 to 7000 miles some cant believe I am using a loop, breaking into pileups I found is a no no but thats just my view. It, is great antenna, now to mount it horizontal wait 6 months
 
AD0AR Rating: 5/5 Oct 26, 2014 17:25 Send this review to a friend
Best compromise antenna for 40M  Time owned: more than 12 months
For everyone who wants to get the best compromise antenna performance in a small package on 40M, this is it.
It's no full sized dipole but for us amateurs who have limited outdoor space, look no further.
I have tried hamstick dipoles, screwdriver antennas, an antenna tuner and a 30 foot vertical, but nothing works as good as this magnetic loop antenna mounted on top of my house.
All this and it doesn't require a ground or any radials for awesome performance!
I tried both vertical (with rotator) and horizontal mountings and I ended up going with the horizontal as the noise floor is really darn low!
Comparing the noise floor of the MFJ-1788 to my HF verticals- The verticals usually have s3-s5 noise levels even on a quiet day and switching to the loop the noise drops to s0.
I live on the edge of town so no doubt I am picking up some QRM, but this loop cuts through it like no other antenna I have tried!
The antenna does drift in resonant frequency as the outdoor temperature varies through the day so it does require periodic tuning to stay on frequency.
I have been using this for 2 years now with only one hiccup. When the polar vortex moves in here at winter time and the temperature dips below zero, RX becomes intermittent. As soon as it warms up a bit above zero, everything is fine. SWR's during the time the antenna is not wanting to RX show fine/ok on the analyzer. SMH
I made a common mode choke from two Amidon 31 cores with 17 turns and three Amidon 43 ferrite beads with 3 turns on each bead. I then attached it to the feedpoint to isolate the antenna from any common mode noise ingress from the shield of the feedline. I found that this has increased the usable bandwidth at 40M by at least 1 Khz. Before this, I found that I would be exceeding the narrow bandwidth of the antenna on SSB, but now it is no problem!
On the air tests show at least a 55 to 59 report consistently stateside with obvious weaker reports on the East and West coasts. I did get some stronger reports when vertically mounted, but the noise floor was at least s1-s3 higher making QSO's harder during noisier band conditions.
Stats for using 40M on this antenna:
20 DXCC worked
43 states worked
Most distant contact: VK5EI Australia
All contacts made with this antenna are with it horizontally mounted 8 feet above a steel roof!
I tuned the feedloop with a Youkits FG-01 to help null out the close proximity of the medal roof and it works wonders with the highest SWR encountered on 40M is 1.3:1 SWR.
I suggest MFJ to make a QRO version of this loop and as we are heading for a solar minimum, perhaps a larger, more efficient 40-80M version loop as well.
Good luck and good DX!
In God we trust, all others we monitor,
AD0AR


 
VE3OOM Rating: 4/5 Oct 17, 2014 10:04 Send this review to a friend
Not bad-could be better  Time owned: 6 to 12 months
The MFJ-1788 was purchased on 17 Mar 2014 and after using it since then, I found mostly pros and very little cons with this antenna.
As a stealth antenna itís great for apartment dwellers like myself.
I have tried both horizontal and now vertical and because of high powered lines in my area, I find the vertical works best especially with an added rotator.
Now the Cons:
At one time I could not tune it since the clamp inside the loop that stops the capacitor had come loose preventing the capacitor stopping at the precise location.
On the horizontal, I had to use several tie wraps to prevent the clamp from giving way.
Now I find the screws that are holding the loop housing is stripping away. That was quickly remedied by adding silicone.

For the price of the unit, all-in-all MFJ could do a better job of quality control or lower the price.
73 Don VE3EM/VE3OOM
 
VE6EFR Rating: 5/5 Aug 21, 2014 19:01 Send this review to a friend
Update to my previous review  Time owned: more than 12 months
I wanted to update my original review, copied below.

After using this antenna for a while, I am still very impressed. As of this writing (August 20, 2014) I have confirmed 39 countries and 41 states on Logbook Of The World using this antenna and 100 watts. This antenna has worked flawlessly and I have not had any mechanical issues or otherwise.

After seeing how this antenna performs, a friend of mine that is working toward getting his license has also purchased this antenna for use at his house. Being in an antenna restricted area, we installed the MFJ-1788 in the rafters of his garage. His antenna also works like a charm. It is relatively quiet and we are able to work DX stations with little difficulty. If we can hear them, we can work them.

Once you have the antenna installed, tuning does take a little practice to get used to. But over all you can't go wrong with this antenna in a limited space environment.

73 - Jeff VE6EFR

Original Review:

Living in a 16th floor apartment I thought that HF was beyond my grasp. That is when a friend let me borrow his MFJ1786. After using it for a few weeks I was hooked.

I decided to purchase the MFJ1788 because I wanted an antenna that I could use 24/7 instead of being confined to the higher daytime HF bands or running CW on 30 meters.

This antenna does not disappoint. SWR is 1:1 on all bands even though I have a lot of metal nearby such as the balcony rail, rebar in the concrete, etc. So far I have worked 29 countries and counting. Granted, having it mounted on a balcony 160 feet above ground doesn't hurt. I am able to get very similar signal reports as several nearby friends running a G5RV or a full size dipole. If you would like to see a picture of this antenna and how it is mounted look me up on QRZ.

As stated before tuning is a little tricky, but once you get the hang of it it's a snap. This antenna is a great investment and one I would not hesitate to recommend.
 
N6MV Rating: 2/5 May 26, 2014 17:50 Send this review to a friend
Operating with an MFJ 1788 and MFJ 1786 Loop   Time owned: more than 12 months
Have used both a MFJ 1788, that covers 40-15 meters, and an MFJ 1786 that covers 20-10 meters. Both loops are 3 ft in diameter, and whereas the MFJ 1788 works great from 20 to 15 meters, and the MFJ 1786 works great from 20 to 10 meters, the MFJ 1788 is a "wet noodle" on 40 meters -simply because the loop -at 3 ft diameter - is way too small on 40 meters, with a radiation efficiency of less than 10% ! The ARRL also found this out when it reviewed the MFJ 1788 in the March 1998 issue of QST,where the ARRL stated: "On 40 meters the MFJ 1788 just did not cut the mustard with other antennas". In sum,
definitely recommend purchasing an MFJ 1786 which works great - only 3 ft off the ground -on 20 to 10 meters, but that's not the case with the MFJ 1788 on 40 meters, for the diameter of the loop needs to be 5 to 6 ft in diameter - and at 3 ft at 40 meters, it is a wet noodle, that simply doesn't cut the mustard.

73's Jim (N6MV)
 
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