| AD0AR |
Rating:      |
2014-10-26 | |
| 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
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| VE3OOM |
Rating:     |
2014-10-17 | |
| 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 it’s 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 |
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| VE6EFR |
Rating:      |
2014-08-21 | |
| 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. |
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| N6MV |
Rating:   |
2014-05-26 | |
| 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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| M3UHQ |
Rating:     |
2014-04-22 | |
| Ive only had it a few days. |
Time Owned: 0 to 3 months. |
I have had this antenna a few days now, and whilst it has got its QC issues it does a mighty fine job, I heard Hawaii on the loop using it indoors, Ive not yet had any real DX, but certainly can hear other stations, its pricy but if like me you have antenna problems outside or you have a noisey neighborhood because of QRM/N. Get it, you wotn regret it. 73
I will write some more when Ive used it more and have had some confirmed qsl's/ |
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| VA3TKO |
Rating:     |
2014-03-18 | |
| Initial findings of my MFJ1788 |
Time Owned: 0 to 3 months. |
MFJ 1788
Recently purchased the a new MFJ 1788. When the box arrived from the supplier, I noticed one side of the box had been opened and re- taped with clear tape.
I first mounted the antenna on a 8 FT galvanized pole away from any objects in the back yard. I carefully read and followed all the instructions from the operating manual provided. Yes....I had to widen the holes on the vertical support brackets so the hardware would fit properly. That took 10 minutes with a cordless drill.
When I first powered up the control box, I could not get my " FAST" DOWN LED on the right to illuminate. First thoughts were of the quality control at MFJ. AFTER TRYING OVER AND OVER, and failing to get the antenna tuned on 20 meters I decided to take a look inside the plastic covers of the loop itself. I had read some blogs suggesting the checking of solder joints if the antenna was not working. So off the covers came. Within a few minutes I noticed one side of the internal loop wire had a cold solder joint. The end of the internal loop could be moved in and out of the solder joint freely. I resoldered the joint, remounted the antenna and presto.....all LED's were now working. I managed to somewhat tune some of the 20 M band but the SWR at best was 2:1. I had read in another blog that if your internal loop was turned out on one side compared to your 36" loop you may improve your SWR.. I tried it and WAALA," got an SWR OF 1:1 at a full 100 watts. Now the test...( I live in Florida) I heard a station about an S9 on 20 meters. I retuned to that frequency and attempted contact. Immediately I get as response back ...a clear 59 signal to Richmond Virginia. Happy I had made a contact I wondered what the antenna would do closer to the ground. I placed the antenna on the top of a plastic garbage can ( approx 24" in height) in the vertical position from ground. I went back to the radio found another station on 20 meters, retuned, gave out my call and again got a 59 response. He also was located in Virginia. When I told the contact about my antenna and that it was sitting on top of a plastic garbage can he laughed and said I can't believe it. ....that I was a little stronger than another Florida station in FT Lauderdale that was running a beam pointed at him. He was quite excited and started talking to others in his group asking if the could copy me as well.
Pretty cool. In closing despite the few hiccups...I am glad I purchased the antenna.
I just wish MFJ would place some emphasis on Quality Control. Oh yes one other thing.
I called the MFJ Technical Support number listed on the instruction manual for the 1788....A lady answered and told me that I had the wrong number and that MFJ has a new number and has for some time.
She seemed a little irritated.
Anyway, I hope this review helps. 73. VA3TKO
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| W9JY |
Rating:      |
2013-11-19 | |
| Great for Small Spaces |
Time Owned: more than 12 months. |
I have both the 1786 and the 1788 from MFJ. They are the same design but they cover different bands. I have them each mounted on MFJ 1918 antenna stands.
I live in a townhouse in the city. I've tried lots of compromise antennas. I've tried verticals. I've tried indoor random wires with tuners. I've found that nothing beats the magnetic loop in terms of performance and convenience for small spaces.
The loops are about 3 feet in diameter. They don't require any radial wires like a vertical antenna does. They are easy to set up and put away when not in use. The tuning is semi-automatic using a control box. I found the tuning procedure easy to master. The tuning box sends the control signal over the same coax as the rf signal. This eliminates the need for a separate control cable. The control box requires power. It comes with a wall wart power supply. It also has an internal battery holder for AA batteries. I use the wall wart power supply when I'm operating from inside. When I'm outside I use AA batteries in the control box.
I've made contacts using PSK31 on HF all over the country as well as internationally with these antennas.
The only drawback to the design is narrow bandwidth. If you move up and down the band you will have to retune again. Retuning is pretty easy, though, so for me it is not a deal breaker. It is a small compromise to make considering the convenience and performance of the antenna. |
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| W5XE |
Rating:      |
2013-07-29 | |
| excellent |
Time Owned: 3 to 6 months. |
I purchased the 1788 in March and installed it
on a fence at the 6 foot level. Worked very well
even at my normal qrp level of less than 5 watts.
I use it mostly on 30 and 20 where it does an
outstanding job. Wanting to see how well the
performance was at a higher level, I moved it to
25 ft over the top of my mobile home. I saw no
difference in performance or signal levels, so
relocated the antenna to the fence location.
I hear many dx stations when the bands are open
and it hears as well as my vertical and dxcc
dipole. Well satisfied. |
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| G6YEK |
Rating:      |
2013-07-28 | |
| GREAT |
Time Owned: 0 to 3 months. |
Owned now for only 3 days,FANTASTIC only 6 feet above the ground.
Des G6YEK |
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| VE3MCA |
Rating:      |
2013-01-15 | |
| Great low profile antenna |
Time Owned: 0 to 3 months. |
| This past weekend (Jan 12/13, 2013) I installed the MFJ-1788 outside in my yard about 7 feet above ground on a metal pole. The antenna is setup vertically with the loop ends in a NE/SW direction. The antenna is about 15 feet away from the main house and 8 feet from the carport (brick, vinyl siding with some metal trim). Coax cable run is about 50 feet of RG-213. During the installation, the only issue that came up was when I was attaching the brackets to the base of the antenna. The taps were slightly off and it took some time and patience to get the bracket to screw in flush and straight. Once that was done, the rest of the install and setup was a breeze. Ensure you read the instruction manual, especially when it comes time to tune the antenna. It takes some practice and patience to get the tuning down. First few attempts to tune, I was wondering why is it taking so long to tune and I would stop short of a proper tune thinking there was something wrong with the antenna or the location of the antenna. It is normal to wait 30 seconds or longer to see the SWR needle begin to drop (guess I was used to automatic tuners that only take a few seconds to tune). I have also posted a video on youtube on the tuning procedure to help others out. Once I got the antenna to tune, I was on the air making PSK31 DX contacts in no time. Some of the contact made within the first day..from my QTH in London, Ontario, Canada -- Czech Republic (OK1EP); Austria (OE9PCJ); Estonia (ES3RM); Sweden (SA7BWV); Dominican Republic (HI8CAR); Slovenia (S52UF) and many local North American contacts. Signal reports were mostly 599 to lowest 469. Running between 30 to 80 watts using Kenwood TS-480HX. Overall, I am pleased with the performance of the antenna. The workmanship on the head unit is fine, everything works and cabinet is square and set well. Again, the only issue was when attaching the brackets/screws to the pre-drilled holes which were slightly off making it a chore to set the bracket straight. Considering the size of the antenna, the performance is awesome and a relief for me as I am in an antenna restricted neighbourhood. I have tried the MFJ apartment antenna with the base coil and clips, and Buddipole antenna (vertical config.) with only satisfactory results. Sure, the price of the MFJ-1788 is on the high end, but that includes a tuner which provides easy calibration to an antenna that is a fraction of the size of many other HF antennas and it gets out with great signal reports. |
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