MFJ-1786 Magnetic Loop

[camaro1]

sometimes you need to change the shape of the wire loop inside to get the best results on all bands

 

[jon666]

i got the same loop i was having the same issue. took the black plastic off to find no screw holding the cap. in place put it back together works great now

 

[sp9hzx]

My MFJ1788 works perfect.Good quality,easy tune.
280 countries.done with it


www.qsl.net/sp9hzx

 

[Need2Know]

My MFJ1788 works perfect.Good quality,easy tune.
280 countries.done with it


www.qsl.net/sp9hzx

I have a 1788 on order from DX Eng - delivery not expected till Dec or Jan. But I am still debating the pros and cons of the 10 to 30 meter vs the 15 to 40 meter.

Very inefficient and very narrow on 40 but no phone on 30 so the 10 to 30 version is basically limited to 10 to 20 meters on phone. The 10-30 receives CB.

So what do you guys suggest between the 2 versions.? Why did you get one version instead of the other?

 

[DJR]

I have a 1788 on order from DX Eng - delivery not expected till Dec or Jan. But I am still debating the pros and cons of the 10 to 30 meter vs the 15 to 40 meter.

Very inefficient and very narrow on 40 but no phone on 30 so the 10 to 30 version is basically limited to 10 to 20 meters on phone. The 10-30 receives CB.

So what do you guys suggest between the 2 versions.? Why did you get one version instead of the other?

I live in a high-rise condo and my antenna options are severely limited so I chose the MFJ-1788. I purchased mine second-hand at about half the cost of a new one. I use it on my 3rd floor balcony (at night to avoid scrutiny/complaints from the condo association) with about 15 feet of RG-8X coax using a Comet CTC-50M window feed-through, and an additional 10 feet of RG-8X with a MFJ-915 RF Line Isolator inside connected to the MFJ controller. The antenna is somewhat heavy, but it's relatively easy to put up and take down, and it's pretty durable. I use 6' of PVC pipe as a mast, strapped to the railing with Velcro straps. Since I use it at night, 10M is useless for me, and 40M seems to work regardless of solar cycle conditions vs. 10M or 12M anyway. I primarily operate FT8 & FT4 which makes either the 1786 or 1788 ideal, since there is no frequency spread to tune. Regardless, I had to adjust the shape of the smaller loop inside the MFJ-1788 antenna to improve my SWR. (Made it more circular than oval.) I can now tune 40, 30, and 20 meters to less than 1.5:1 (20M is a flat 1.0:1); and 17 and 15 meters to less than 2.0:1. So, I have a 5-band antenna. AND, I've found that once I've fine tuned the controller to the lowest SWR, there is still room to further fine tune to bring the radio's displayed SWR down to nearly match the controller's display. I've also found that I cannot use the antenna vertically. I have to use it horizontally to achieve low SWR, and I can't use it inside, I have to use it outside. At heights over 20 feet, the antenna is recommended to be used horizontally anyway. The antenna takes some patience and getting used-to, but I've found that it works pretty well. One must remember that these are "compromise" antennas. You will likely not achieve a perfect SWR on all bands to begin with. Anything less than 2.0:1 is decent enough to operate. I operate at 25 watts or less. While admittedly QSOs are challenging, I have been able to work New Zealand, Australia, South Africa, Reunion Island, and much of western Europe and central Europe from my southeast Florida QTH.

 

[Need2Know]

I live in a high-rise condo and my antenna options are severely limited so I chose the MFJ-1788. I purchased mine second-hand at about half the cost of a new one. I use it on my 3rd floor balcony (at night to avoid scrutiny/complaints from the condo association) with about 15 feet of RG-8X coax using a Comet CTC-50M window feed-through, and an additional 10 feet of RG-8X with a MFJ-915 RF Line Isolator inside connected to the MFJ controller. The antenna is somewhat heavy, but it's relatively easy to put up and take down, and it's pretty durable. I use 6' of PVC pipe as a mast, strapped to the railing with Velcro straps. Since I use it at night, 10M is useless for me, and 40M seems to work regardless of solar cycle conditions vs. 10M or 12M anyway. I primarily operate FT8 & FT4 which makes either the 1786 or 1788 ideal, since there is no frequency spread to tune. Regardless, I had to adjust the shape of the smaller loop inside the MFJ-1788 antenna to improve my SWR. (Made it more circular than oval.) I can now tune 40, 30, and 20 meters to less than 1.5:1 (20M is a flat 1.0:1); and 17 and 15 meters to less than 2.0:1. So, I have a 5-band antenna. AND, I've found that once I've fine tuned the controller to the lowest SWR, there is still room to further fine tune to bring the radio's displayed SWR down to nearly match the controller's display. I've also found that I cannot use the antenna vertically. I have to use it horizontally to achieve low SWR, and I can't use it inside, I have to use it outside. At heights over 20 feet, the antenna is recommended to be used horizontally anyway. The antenna takes some patience and getting used-to, but I've found that it works pretty well. One must remember that these are "compromise" antennas. You will likely not achieve a perfect SWR on all bands to begin with. Anything less than 2.0:1 is decent enough to operate. I operate at 25 watts or less. While admittedly QSOs are challenging, I have been able to work New Zealand, Australia, South Africa, Reunion Island, and much of western Europe and central Europe from my southeast Florida QTH.

Good review. Every antenna is a compromise in some form or other: Size, range, tuning, bands, portability, etc. I decided on a 1786, just received it and I'm in the process of tweaking it. The solar cycle is just right, and for the next 3 or 4 years beyond 2024, for the 10 to 30 meter version.

 

[Need2Know]

What have you guys found to be the best height off the ground for vertical orientation? My tripod allows the bottom of the loop to be anywhere between 4 feet and 6 feet from the ground. Raising it from 4' to near 5' seemed to improve the SWR from 1.4 to 1.2 on 21.3 MHz.

What shape of the feed loop between perfectly round and oval have you experienced the best performance?

Have you gone inside the control head to slow down the slow tune function if required, per the User Manual. I may try that later.

 

[Riverman]

What have you guys found to be the best height off the ground for vertical orientation? My tripod allows the bottom of the loop to be anywhere between 4 feet and 6 feet from the ground. Raising it from 4' to near 5' seemed to improve the SWR from 1.4 to 1.2 on 21.3 MHz.
What shape of the feed loop between perfectly round and oval have you experienced the best performance? Have you gone inside the control head to slow down the slow tune function if required, per the User Manual. I may try that later.

With all the magnetic loops I’ve had, I found round, oval and anything in between showed no difference in performance. All worked good. Same for height above ground (or floor). Three feet and higher.

Speaking of loops, I even have one for sale currently in the Swapshop.