Using the MFJ-1788 Mag Loop Antenna Horizontally (
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- Опубліковано 5 чер 2018
- I test the MFJ-1788 in a horizontal position on my rooftop. The performance is great on 20m. I used an MFJ Cobweb antenna as the comparison antenna.
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Perfect, helped me understand my mounting was not wrong and would work. Now I can tune my antenna and am working well.
Dave:
I purchased an MFJ-1788 in August 2019 and finally put it up in a vertical orientation. I could not install due to an injury I sustained shortly after the purchase until recently. I am not impressed with this antenna and seem to get better performance out of my cheapie wire antenna bought off eBay. It seems as though MFJ is fairly directional and it needs to be rotated. That’s fine and dandy if you have a rotor, but not so much when one must loosen the antenna mount to twist around in a different direction. By then, band conditions change.
I am very disappointed in the construction quality of this antenna. Right out of the box, the press fit mounting nuts in the aluminum frame of antenna came loose and made removal of hex bolts impossible. The bolts had to be cut off. The plastic cover is a piece of junk. The antenna I received had the screw holes stripped out and the screws would not hold. Consequently I had to go with larger screws to close the cover.
For an antenna approaching $600 in price, this is not a good investment.
Thank you for the information.
The really neat thing about those antennas is the very sharp null when the loop is perpendicular to the direction of arrival of the signal. One of those on a rotator can tell you with a pretty high degree of accuracy the direction to a transmitter. I used them when I was in the military for man portable direction finding operations. You make me want to put one up on a rotator outside the shack. =)
I've looked for rotators but haven't got one yet. I wish I could find one that would rotate really fast so I could really home in on the null.
Thanks you so much for the additional info on the MFJ-1788 Loop antenna. I have been on the fence about purchasing one of these antennas. Not only because of the high cost and the many "Quality Control" issues I read on the review sites, but also wondering how well it would perform outdoors compared to my indoor attic mounted 37' OCF dipole for 40m-6m. I am thinking my HOA would probably tolerate the MFJ-1788 mounted outside my house on a roof eve high pole, much like the satellite TV dishes mounted on the roof edges here now. I wish I knew if it would perform $500 worth better than my $89 inside attic mounted OCFD. My OCFD does not do well on 40m but is pretty decent on 20m-6m considering it's indoors in a leaning "L" shape. Sounds very much like the same results as you are getting with the MFJ-1788 Loop. Oh the miseries of living in an HOA community.....lol!
Sorry I missed meeting you last Saturday at the tailgate. Several people there I hadn't seen in years.
Hi David, great video. I thought of buying a Ciro Mazzoni baby loop and was wondering how a vertically mounted near the ground would do vs something like a DX Commander multiband vertical in terms of DX long distance contacts. I don’t have an HIA but would like to avoid the radials and have something portable.
The loop is certainly portable, although some are more portable than others. I've not really studied loops at ground level.
Hi Dave. Where can i find this „straight key“ for the „tuning tone“ you mentioned, on the FT-DX 3000? I usually switch to AM and tune with a low power signal (15W) to watch the SWR. Cheers, Stefan Df6vi
@ZLcloud22 So, unfortunately we will obviously never know, how Dave is tuning the DX 3000? Meanwhile i got a new Radio (Flex 6400M) with a real "Tunebutton". That's much more comfortable and i like VERY much. 73'
Hi Dave. Excellent video - again, thank you. Two things: 1/ Could it be that the higher noise floor seen on the MFJ Loop was because it was located on the house, so closer to all the noise sources in the building? The cobwebb is mounted further away. 2/ Is there any way that an SDR Play, or something like it, could be used with a radio that does not have an RF or IF Out connector on the back? I have a fantastic Yaesu FT-891, but it lacks the connectivity that you mention. I could also ask the same about the FTDX-1200. Perhaps a topic for future videos?? Thanks again Dave. 73, Mike, M0MTJ
First, yes, the MFJ on the roof still picks up quite a bit of household noise. Regarding getting the RF or IF out, if there is no output for it, you may well be out of luck. You can get a device from MFJ that allows the SDR to share the antenna with the radio when receiving, and then disconnect the SDR while your other radio is transmitting.
@@davecasler Thanks for the tip Dave. I will have a look at the MFJ website, that sound like it could be a neat solution. Thanks for your super videos. 73, Mike, M0MTJ.
It is possible that a magnetic antenna placed in the horizontal plane has three advantages: 1) not having to constantly modify the azimuth or direction to which it points, it is omnidirectional. 2) it captures little "electrical" noise of the population since being "very directive ", will capture the signals that arrive from the horizon but weakly those that come from an angle below the horizon, which is where the electrical noise of population comes from. 3) will preferably pick up the radio signals that arrive in vertical polarization, which is how the rebound signals in the ionosphere usually arrive (janay)
As it turns out on HF, all signals that have been reflected by the ionosphere are circularly polarized. That way, either a vertical or horizontally-polarized antenna can pick them up, which is why polarization is not so important on HF. At VHF or UHF for line of sight, polarization matching is very important.
Dave I see you use your mouse and Im guessing you are reading a script to keep on track. What is it we aren't seeing behind the camera and how are you using it? Im curious as I have a friend who has a video series he wants me to record with my video camera for him. It would be videos for work related safety procedures for his workplace but instead of hand written cue cards I figured a tv or something would work better.??? Thanks for your videos and love the info.
I use Autocue Qstart software. It's not perfect but seems to be very reliable. And, yes, I use a homebrew Teleprompter that uses an inexpensive television set from Walmart, less than $100, and some plain window glass for the reflector.
Wasn’t this video meant to be about the performance of using loop antenna horizontally compared to vertically?....
These are Good to Use when You like on a Neighbor with a HOA,
My buttons do move the frequency up or down as labeled. I suspect the leads to your motors might need be reversed..
Garry
Thanks. I'll have to check it out.
What software are you using for the SDR?
SDRUno. See www.sdrplay.com/
a loop horizontal should be perform omni-directional (from the wiki) and vertical it has two directions. I have a ALA on the balcony here for reception and i found on MW i get better signals in the vertical position but on 40 meter its often better in the horizontal position. Now i don't have a rotor attached so it could be that on 40 meter it null out some signals giving me the impression that horizontal works better. After reading a lot i still haven't seen a good review about horizontal small loops vs vertical... Also i have some online friends who use a high placed vertical loop with a rotor and the bribe about the fact its high in the air. While i have seen in several youtube tests that some height is good but really close to ground a loop still performs well and height doesn't matter that much. As third point everyone has a coupling loop below the main loop while and for tuning they make it more oval but i miss a test where the small loop coupling is above the main loop. I believe alpha antennes recommend that but i haven't seen a youtube movie that really tested that. Then last point i see people most QRP station with a coupling loop on the downside but there are also people mostly in fixed configuration that have the coupling loop on the upper side of the main loop? What are the differences? Or doesn't make any difference where the coupling loop is? Thanks for the video
I've always seen the coupling loop inside the main loop.
Ahaaaaaaaaa Me first one :-) You going to Monument July 7? Yup 20M to the San Luis Valley is short:-)
Yeah, propagation seemed really short that day. Sadly, I won't be going to Monument.
Mal auf deutsch sprechen