MFJ 1788 Loop Antenna Fixed (#65)
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- เผยแพร่เมื่อ 26 ส.ค. 2024
- After several videos and disappointments, the MFJ-1788 Hi-Q Loop Antenna didn't work on 40 m. Now it does! I took it apart to discover that the big capacitor was not fully meshing because of a mis-set limit switch. See how it works! Subscribe: / davidcasler . Ask Dave Playlist: goo.gl/inaQeB. Tip Jar: ke0og.net/tip-jar
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I know this is an old video,but for a nearly $600 antenna, that is some pretty shoddy quality!
THANKS, DAVE, 6 years after the original posting. The information remains valid to this day. 73 from Ohio. W8YI
Glad you found the issue. Being retired and on a fixed income it is important that what you purchase is manufactured properly without defects. Thankyou for your presentation. MFJ will be removed from my consideration.
Hi David - I had the same problem with an MFJ-1788 loop antenna I ordered from Gigaparts 2 years ago. It was going to cost me $105 to send it back to Gigaparts via UPS. I then opened up the antenna and found the limit switch stop problem you came across and there were several capacitor plates bent and shorted together. It now works fine. Bob - W3ARA
Thank you SO much for following up and showing what was wrong and how you fixed it. My first piece of MFJ gear in 1992 was an MFJ-949D Antenna tuner. Bought it brand new from MFJ and it didn't work right out of the box. I was upset being a newly licensed Ham and waiting for this tuner to arrive in the mail to get on the air. Fortunately my Dad was a Ham in the 50's and 60's and a Radio-TV repairman for 30 years. He opened it up and was able to repair it. My experience has shown that you have a 50/50 chance of a new MFJ product working out of the box new. I can't count the MFJ items I have had to repair out of the box. I still buy MFJ products because when they work they are well worth the money. If they don' then you get more electronics experience repairing it. But come on MFJ! You can do better.....
Glad you got the antenna working. I have the same one. My take away from web searches about the antenna before I bought mine was you ALWAYS have to open it up and inspect the soldering, plate movement/alignment...basicly everything. I found plates that would touch at the end of rotation. Not a big deal to fix. So, please anyone that gets this antenna which works wonders mounted horizontally in my attic, take the plastic cover off and inspect/check plate movement.
Gr8 news. I bought one several years ago, it would not go all the way to the bottom of 40m. Sent it back to MFJ, they returned it with the same exact problem. Now I know how to fix it myself. I did open the cover, but did not think to move the capacitor to see it mesh. Thanks Dave, now I know.
Glad you got fixed. I remember the old saying...MFJ = Mighty Fine Junk
oh HOW original .. not ..
rob b They'll keep it going like a dead horse.
Have the exact same problem Dave- the antenna is just sitting in the box it came in after a few months of use- Thx for showing what the heck is going on-
Appreciate your candor on this situation-
I had a similar scenario with the MFJ 935b magnetic loop tuner. It stopped tuning in all bands within a few days of receiving it. I opened it saw that a toroid that goes around the tuning capacitor screw was off center and very close to it. I sent it back for warranty repair and when I got it back I opened the unit to find out all they did was to put a piece of heat shrink tube around the capacitor screw. I called support and asked why the toroid was still not properly aligned and I was told the problem was referred to the manufacturing department. The unit so far works fine but it goes to show you, like in your case, their quality control leaves a lot to be desired. It's a shame because I have quite a few MFJ products and I rather buy items made in the US but situations like this makes you think twice where you spend your hard earned money. Glad you got it fixed and great job on your videos. 73, Tom
They offer so many products that are unique in the marketplace. That being the case, they're a great asset to amateur radio. But, like any manufacturer, they can be frustrating at times.
This is one reason I bought the Baby loop from italy and not the MFJ one. I have a few MFJ items and have also had minor quality problems, knobs stiff or not working right, screws missing etc. I have also had problems with BHi stuff as well and Heil suprisingly !
I think the fact that MFJ allows amateur radio operators to try and fix it themselves without voiding the warranty is in line with the spirit of ham radio. I like that.
The spirit of ham radio is about building and tinkering. It is not about fixing brand new equipment that you paid thru the nose to buy. Come on Hoshnasi. Please point out one of your videos where you have been pleased at the opportunity to fix something that you bought as new.
@@jackfiamingo9180 Well they are infamous for producing junk so they have to do something to keep people from sending stuff back all the time. I agree with ya the price this thing is I would be mighty pissed if I had to troubleshoot and fix right out of the box. Frankly having to tear it apart and fix something like that I would expect a partial refund since I had to do what I was supposed to be paying somebody else to do.
It's not in the spirit of amateur radio. It's in the spirit of they don't want to get the stuff back and have to work on it themselves. It's a lot easier for you to do their final quality-control. Something they should be doing before it leaves the factory. I bought a mfj 9420 once that had three factory defects right out of the box. But it had a famous mfj QC sticker on the back. There were some initials on the sticker and if I owned mfj that QC inspector would be long gone. There is no way in hell that inspector ever looked at the radio. All issues were very obvious. The CW adapter emitted a sidetone all the time, the transmit LED was put in backwards and the alignment was so far off you couldn't get 5 Watts out of the rig. It shawty QC like this that gives mfj a bad name. Obviously nobody cares at mfj because it goes on year after year after year. I would assume that they also look at the reviews that they get on equipment. This cannot be news to them.
That's why they call it "Mighty-Fine-Junk!"
I've had a number of MFJ products that I've either had to fix or they just never would work to any satisfaction.
The latest saga is with a MFJ-1025 Noise Canceller; I'm the 4th ham to get this thing. Although you can here it seemingly changing phase (to give you the idea it is working) it never seems to get a very deep null no matter what type of noise antenna I try. So, I'm wondering if this has some type of factory defect whereby a transformer is not phased correctly or something.
Anyway, great video Dave and I agree with you assessment.
There is an old saying: "There is never time enough to do it right the first time, but always time enough to do it over!" 73...
MFJ get your quality under control! Glad to hear ya got 'er fixed Dave.
I have had my MFJ-1788 now for 3 years, it works great. But after a few weeks the antenna would not tune, it turned out that the same grub screw that holds the centre plates of the capacitor in place, worked it's way loose and the plate dropped onto the other plates, re-aligned, tightened screw, FIXED. Apart from that, I am extremely happy with my loop antenna.
Ray in Melbourne.
a few months ago I saw another video about this antenna with the same issue and it was also caused by the miss set limit switch
David great work. For someone like me, I never would have been able to discover the problem and fix it. I pay my hard earned $ and expect a product without defects. That's why I chose the Chameleon F Loop and the P Loop 2 which are top quality and work just fine . Thanks for the videos.. I appreciate all you help and advice. Larry
Larry Nathanson and those are qrp loops not 100w rated. Those looking at these loops know about the cha loops and still pass or build their own.
@@darthorpheus According to MFJ, its rated at 150 watts
@@darthorpheus I notice too that many other HAMs are quick to point out other manufacturers Loop antennas being far better and they are. I just wish they realized that they only handle 10-20 watts while the MFJ will handle 100 watts. I also wish MFJ would especially focus on the quality control of these antennas since they are so ridiculously overpriced. That would be the least they could do. I seriously considered purchasing one until I read endless nightmare stories about the problems straight out of the shipping carton.
I had to tighten the capacitor to the shaft myself. The symptom was that the capacitor was not turning at all. The motor was running, but nothing happened on the tuning box needles; so a call to tech support solved that, much as yours did, David. I enjoy your vids and I now subscribe! 73!
Welcome aboard!
Nice work Dave, I bought a (Bare Bones) MFJ 10 to 30 megs loop from ebay ie - no controller no circuit no 1 -5th loop and the motor was fubar .
Cost about £40 delivered, its up and running now with a new mfj motor (old type) and a £3 12v reversible controller again from ebay. I use an extra cable to move the motor, tune for max noise and then rock it back and forward for lowest swr , bingo.
I understand about the Quality issues but what a great range of products they have.
Thanks for your video! My MFJ-1788 Hi-Q Loop Antenna would also not tune the entire 40m band. The big capacitor was fully meshing, but the plates on the rotating shaft were not in good alignment. I was able to align them by loosening the variable plate shaft from the motor using allen wrench, then loosening the nut on the shaft, freeing the plates to move independently, then aligning the plates using a couple pair of needle nose pliers. After which I made sure that the limit bar, also on the shaft, was correctly positioned to engage the limit switch when the capacitor was fully meshed. After tightening the nut on the shaft, then the allen wrench screw to re-engage the motor shaft, this antenna will now tune to the low end of the 40m band. MFJ should have tested before shipping, and the misalignment of the blades was visually obvious. So, I think they have a quality control issue!
MFJ has been told this for years. People complain to them about quality control at the Dayton Hamvention and other hamfest. I have personally witnessed various people complaining. It falls on deaf ears. Honestly many amateurs no longer Homebrew and this is where mfj's market lies. many do not have the time equipment or skills to build an antenna tuner or a magnetic loop or "insert your favorite project here".
the only thing that might make them take notice is when people stop buying their products, but that's not likely to happen. The engineering behind many of their devices is actually quite good. It's the assembly in quality control that lets them down every time. I purchased a new mfj 9420 years ago and it had multiple issues right out of the box. It was not aligned properly, the TX LED was installed backwards so it would not light, the CW adapter side tone sonaleart sounded all the time, and transmit power was low because of the mis- alignment. Also the rig drifted worse than a swan 350 ever did. It made the swan look stable and I'm not joking. I had to put a call into the rig's designer Rich Littlefield . He told me that the vfo oscillator coil was the wrong type and there was no way to settle the oscillator down without replacing the inductor for the correct part. I contacted mfj and to their credit they did send me a new coil out for free. But this is one item with this many faults. It is just unreal. W8JI makes claims that he designed a quality control program for mfj and I believe him. For whatever reason, they don't follow it.
Again, thanks for video. Although it is too bad the 1788 was shipped somewhat defective, it is inspiring to see you use your technical know how to fix the problem. I think that is part and parcel of the "Ham Radio Spirit." The fact that MFJ allows their customers to do so without voiding their warranty is a credit to them in their favor. On the other hand, like you said, this sort of thing should have been rectified in Quality Control and that doesn't speak well of them. Either way, thanks for your honest review. I think this is a reminder that even a product from a reputable company has to be evaluated on a product-by-product basis. Best regards, KM4HOC.
My 1788 had a bad solder joint connecting the tuning coil to the loop. After correcting that the antenna has been great. I get very low SWR 15-40M and good signal reports, even qrp.
Hi Dave, I too have had problems with MFJ, 1 was a 2m/70cm base antenna, 2 was a tuner with 2 issues, 3 is support. I find it hard to trust MFJ, Their Quality Control sucks. Their Warranty is there for them, You buy a defective item when paying for a working item, then you/we fix it at/on our time to save MFJ money on repair time and shipping.
Well done Dave. I understand your frustration. Like you I have a few MFJ items and I've repaired a few. Not many though. Most Hams probably have MFJ items for that matter. QC is definitely one of their shortcomings. While I'm glad to see that they don't void the warranty when the owner makes a repair I I think that policy somewhat reflects the QC issue. 73 NE5U
I have had similar problems in the past and the fix was usually something simple, like bad solder joints. I still purchase their products and use them daily. We are hams and "can do" people. I recognize they are NOT Elecraft but am glad they stay in business. They offer so many different products that make this hobby more fun. I still use one of their first CW audio filters bought back in the 70's when they first started.
Dave K8WPE
Yes, I have quite a few MFJ products also. I think they're pretty essential to modern ham radio.
Your too kind Dave to MFJ this should not have happened as we all know. well done showing us your findings ,from The UK best regards.
Glad to see it working I know in my years of manufacturing that a good qc program would have caught that also having a good process in place with checks even before it hits qc would have helped a lot.
Wow David, I am so happy that this video of yours was made. The impression I received from MFJ was (a don't care attitude from the lady that answered my phone call) that if you are not patient about their back orders (they have so many) that they will give your money back. This from a Ham's perspective is not good since what we want is a working product. I agree with every sentiment in this video. $500 is not a cheap antenna by any means. I received a signal tracer/injector and the potentiometer shafts were bent. Quality control should be MFJ's major concern for 2017 and beyond. They do have a wonderful range of products which can only be enhanced by proper Work Procedures (WP) and Work Instructions (WI) which will lead to a high level of Quality Control. AC4PS.
I'm afraid I spoke with the same lady. But when I called for Tech Support I got Paul, who was far more helpful.
Glad you got it working. I imagine some hams have this antenna with same issue. That is the sad part. They may have subpar performance & live with it or don't use 40 m to know the antenna may not work.
Recently purchased one used a very large discount. The power wires for the motor weren't soldered to the board, and the capacitor set screw was loose. Easy fix at least.
MFJ makes some good products, but they need to work on their quality control. I've been licensed since 1988 and this was a problem back then. I've personally smoked an MFJ tuner running about 20 watts on 80 into a 60 foot half wave open loop. I just sent it back and got a refund. I used their 1621 54inch whip in apartment and didn't work every contact, but still had a good time on ham radio even when I had no space for antennas. I thought about getting the 1786 version of this loop, but still not so sure.
Very well done Dave, QC certainly shouldn't be too much to ask for - yet it is certainly lacking sometimes. 73!
I agree it should be plug and play at the price point. I also agree it is worth a look before going through the hassle of a return. I have fixed too many "new" products and have had good results buying refurbs when I can. It seems refurbs are tested better since they came back with issues. I have yet to have an issue with one (ham gear, power tools, etc...). Thanks for the video! I will do a complete check before I install mine. 73
Hi Dave, excellent video and great to see you. I still have your book and remember the fun FEMA and MIP times. 73s, Fernando
Your absolutely right. You should not have had to fix it. Iv had similar problem with them before also
This morning Charlie Ray and I were having a good conversation and Charlie told me that he was having very good experiences with his MFJ Loop. I told him that Dave Casler was complaining that his loop would not tune 40 meters. I speculated that the problem was that the limit switches were not synchronized with the capacitor. Charlie Ray thought that was probably the solution, and I intended to communicate that to Dave Casler. When I got home and started going through the TH-cam I discovered this video where Dave discovered and resolved the problem, and it was just as suspected.
Had to fiddle with mine also. I would recommend opening up the antenna and checking it before putting it up in the air. Was forced to learn about magnetic loops by having to wrench on mine. Mine had loose screws on the main shaft.
This is quite a while since this TH-cam video that you did but I’m just in countering this with the MFJ 1788 that I bought about three years ago but for various reasons why I was not able to get going with it. And I think I have the same problem. There is a fellow Ham who runs a bit of a radio store here and he has had to fix two MFJ 1788 antennas by going inside and fixing problems like what you’re talking about. It’s quite disappointing considering how much it costs. Anyway I will take it to him on Wednesday and let him figure it out. I think it is something to do with all the plates of the capacitor hit that cut off switch like your problem. Anyway thanks so much for all your TH-cam videos. I watch them avidly. I am an old ham just getting back into the business. I was a ham at age 15 in 1957, then dropped it and now I am getting going again with not HOA restrictions but apartment restrictions. Hugh Jones. VE7YJ. In the late 1950s the bands were spectacular so I would just hook my 10 W transmitter to a length of wire running 60 feet from the front to the back of the white without any coax and I could make great contacts and I never heard about antenna tuner‘s. Were there antenna tuners back then? When I start it up again it was quite a shock how bad the bands were three years ago. The dream receiver back in 1957 was the NC 300. So when I started up here I bought an NC300 from an Ontario ham and tuned it to the bands and couldn’t hear a thing so I junked it. How stupid of me!anyway I’ve got one on my tool bench and another ones arriving in a week or two and I’ll see between the two of them whether I can get one running. The sound of CW on it or of a.m. was out of this world. And it weighs about 68 pounds. You’re just plugged it into the wall hooked up the antenna hooked up a speaker and what a beautiful sound!
Hugh, thanks for sharing. The capacitor plates in the 1788 are made of remarkably soft metal. They can bend if the antenna is bumped hard.
@@davecasler Thanks Steve. My radio savvy repair shop guy found one cold solder joints in the controller and also somewhere else in the antenna wiring there was a wire just hanging by one strand so he’s fixed that and work a bit with the capacitor plates and I get to pick it up tomorrow. He’s fixed quite a few 1788 so I’m quite excited. Definitely bad quality control on MFJ’s part back 4 years or so when I ordered it
@@hughbassoon Sounds like your experience will have a positive outcome. Good luck!
One thing I found about my 1788. The plates on the capacitor were also way out of alignment but after dissembling mine I couldn’t get them to line up. I completely
took the capacitor apart and found the shaft was torqued. I managed to straighten it out with a pair of crescent wrenches. I’m sure it took quite a bit of force at the factory to cause this.
Ouch! Sounds like quite a process to get it right! Glad you were able to fix it.
Great video as always Dave. Considering one for an attic install. Would love to see a video from you with the loop in this type of application.
Our attic access hole is so small I'm not sure I could get the antenna up there! We have no usable space up there--it's all filled with insulation.
Ok, Dave. Thank you.
Well done. Great breakdown on your discovery process and the fix you employed.
Good old MFJ lack of quality control.........infamous!
Thats is the reason I love MFJ and their products. We can work on them without voiding the warranty. My dad last year bought an MFJ-259C antenna analyzer. It was intermittent on 20 meters. After a call with MFJ, they had him open it up and found something loose inside. They told him to go ahead an repair it and it would not void the warranty. Nice to have a company that still believes in personal repair and not having a fit about it. Thanks for all your hard work and videos. Also, by the way, I have started my own channel for some fun and enetertainment for Amateur Radio and DMR. I record on my phone as I am too cheap to do otherwise but would like to have you check them out and see what you think. I am currently uploading a video on the TYT MD-380 and have another waiting on the CPS programming software for such radio. If you do watch them, please comment on how they are or need to be and also maybe some ideas for the channel. Well, that's enough rambling. I look forward to another great KE0OG video and will always have thumbs up for you. 73, ad0am
@Adam Rennison : You buy something with good money, it is defective, you have to open it, dig for the problem and repair by your own and still you're happy because they won't trash the warranty ? Tell me, warranty of what ? A defective device ? Please...
I think the part most likely to fail under warranty is the little motor.
Still, they should do a better job on this antenna . As you said it's expensive and the construction lack on some ways : the enclosure isn't sealed. Saw videos where bees and insects gone inside and made the capacitor arc'ing. The end-switch is another weak part wich fail sometimes. I was nearly to buy it but stopped when i saw videos bout it. In the past MFJ did better stuff and materials were good . But that time has gone. Sadly.
Persistence pays off!
Good job Dave. Now that you got that outta the way... I'm really looking forward to seeing the comparison between the 1788 and the Butternut vertical.
As I said in the comment on the first testing video, I'm not hating on MFJ but it's kinda like Harbor Freight stuff, some works, some don't and some don't work very long.
I have owned several MFJ products (still have a couple), and admittedly, they all worked as intended but I know a number of people that haven't shared my same fortune.
It's a shame really, a little quality control goes a long ways. I think the general opinion of MFJ is not that they make bad products....but that they make good products badly. It's little things like this that fuel the negativity toward the company and it's something that could be easily resolved.... much easier than changing popular opinion.
I really liked my loop for the few months it worked. However the motor has developed a fault making it impossible to tune and I will need to replace it. MFJ quality control strikes again or just unlucky?
MFJ does have quality control issues from time to time as I have experienced. I recently went to installed the CW adapter board in my MFJ-9420 transceiver and when I removed the top cover I noticed that the two pin header that does frequency shift function was completely missing as well as the stand offs that support the board. I emailed MFJ about the missing items and after several false starts when they sent me the wrong items I finally got the parts I needed and was able to install the board and get it properly adjusted. But now I have a new problem, when I try to tune in SSB signals it’s as if the radio is in LSB mode and not USB. Haven’t figured out what’s going on yet but now that I’ve completed my move from California I hope to have more time to dig into it.
Well done for investigating the cause of the problem.. I did consider one of these antennas at one stage but I'm not so sure now. 73 G7MJV - England
I just put it on the roof in a horizontal position. I have about half the makings of a video on the attempt but got distracted.
I don't have the loop antenna but have several other MFJ items. I have had to repair every one of them due to poor construction. I stopped buying anything with MFJ's name on it several years ago because I got tired of having to repair or rebuild something I had just paid for. They may as well sell everything they make as kits because you have to rebuild it anyway.
that is MFJ for ya Dave I have had a few issues with them myself
This has been a great and very informative video series! Glad you were able to get this fixed. I have had a couple of different loop antennas. Currently, I am using the Chameleon P-Loop. I have no complaints with this antenna. However, I have been looking at getting the MFJ-1788 to put in the attic of my new home as I like the remote tuning ability and the power rating. Just have to figure out how to mount it to a rotator. Any advice on that would be most appreciated!
I know its old but I have managed to get SWR right the way down by tweaking the small loop.
Great work Dave. Glad you got it working.
73 AC8VK
Excellent, as all of your videos and comments are. My most recent purchase from MFJ was their QRP Cub transceiver for 20 meters. The kit went together well and this kit has been made for a number of years now. But, boy does it drift! Almost unusable. If I knew that before I purchased it, I would not have bought it! I have many MFJ products and they work okay to good. 73, Karl, KO8S
The old 40m CW 5 watt rig I have drifts too. It has to do with one of the capacitors in the VFO having the wrong temperature coefficient. One way to "solve" the problem is to turn the radio on about 2 hours prior to using it--by then it will have hit a stable temperature. (That's a lousy workaround, but it does work.)
this is a disgrace for a $500 aerial. and it's not the first bad report I have heard from them. huge profit margin on this aeriel. thanks for highlighting the issue
The most expensive element is that gigantic capacitor. Plus the antenna comes with its own controller, which is unique.
Thank you! I just subscribed. Your instruction is clear and efficient. Just got a used MFJ-1786 (free). Long story short: the plastic housing inside the gear box in the motor is broken, so the motor shaft doesn't spin. Do you know of any place in the US to buy a replacement motor? Thanks!
MFJ may have some problems form time to time but just think about all the things us hams use one a daily basis that would not be there without them. YEs their quality control is out of control! I just purchased one of their battery boosters and liked it so much I purchased the remote head for it. Thought I would have to send the head back because it did not work. It uses a cat5 cable between the head and the unit. Just for the heck of it I swaped out a old cat5 cable I had in the junk box and it started working. The problem was a 2$ cable and I almost had to spend the money to return it and they would have had to send more money shipping it back.
What actual use is a warranty, if you actually fix it yourself? You are the warranty. Evidently.
I also had to repair my MFJ loop. The spindle driving the VC was not secured by the grub screw. It just spun the drive loose. It was a pig to repair as I had to file back the end plate to access the grub screw. Truly, there were so many mistakes, in a very small space of work.
I understand. It's very frustrating. Sometimes there's something that you cannot fix, you have to send it back and use the warranty.
Great video Dave.. I was considering purchasing one of these antennas but now I think I will try my hand at making a loop antenna, you should not have to " Repair " a new 500 dollar antenna...
The difficult part about making this yourself is the capacitor. But I have seen videos where people make the capacitor themselves. It's a pretty big project! Good luck with your antenna project!
I enjoy your videos, Dave. Hitting the tip jar now.
73, KJ7RDV
@DavidCasler I have the MFJ 1786X Magnetic Loop Antenna I was wondering if you have any ideas to improve the performance!
Also any ideas that will prevent TVI problems 🤔
Thanks for the videos David. I agree with wat you are telling about mfj manufactoring.
I bought years ago the mfj loop for 10-30 mhz.....Had some failures in the antenna.
The distance between some plates of the capacitor where to small. With a 100 W there where sparks jumping over.
The capacitor was not properly assembled. Also a failure in a soldering on the print in the loop was bad.
Fixed it all and work very fine......but for the price of this antenna it was better to not hurry and take the time in the MFJ factory.
Hope you understand this writting...my englisch is not so good.
Anyway thanks again for the video on youtube 73 de pa3geo
Robert, I've done some more tweaks on my 1788. I'm going to mounted horizontally as high as I can get it and give it a try. I went through everything carefully and tweaked the movement of the capacitor plates so they are evenly spaced and move freely. I did not realize until recently that MFJ has 200 employees. They are essentially the only company that provides every station accessory you can think of, including an extensive line of antennas. It's a balance between high quality and cost. When it comes down to it, many hams are driven by cost, and willing to tweak things if need be. Plus, MFJ stands behind its products. About the only thing they don't do is try to compete with Yaesu, Kenwood, and ICOM.
David, it wil good if you check SWR again, if it has changed
@David Casler what is the name of your book?
The sense of relief is evident.
Congrats Dave
Leg of lamb roasting in the weber now. See ya. 73 VK4SOE/P
Not a major fan or MFJ, having had quite a few of their Friday afternoon products. No wonder at home repairs are encouraged, it's quite a regular feature.
Dave,
Glad you found the problem and a solution. While you had the nut loosened to adjust the stop lever, did you also line up the butterfly leaves? 73 WB3BJU
Pretty much
I was thinking the same thing and wondering if the plates could even be moved...lol!
Hello Dave - We are building a new home and currently I have open trusses exposed for whole attic area. Any thoughts on a choice for an attic antenna - the loop style on a rotating platform in addition to the capacitor controls seems like it would be great -
I think I have at least 4 ft diameter space to hold the antenna. Other dipole options may be possible - I am a new Extra class Ham and just launching my exploration of this fantastic hobby. Thanks
Bruce W2EAL
Great it solved the problem. Wouldn't it have been easier and faster to move the limit switch?
+Apprentice gilligan Actually not. The switch was on a phenolic board and had no adjustment capability. I thought about bending the switch arm, but it would have to have been bent quite a bit. Moving the arm itself turned out to be easy. 73, Dave
MFJ: let us know when you turn pro, and we might begin to look.
This antenna is 719.00 dollars now 😳 for that price it better work,I am on the fence about getting one.
But the same thing always comes up...QC
Nice detective work in getting it fixed and on the 40 band! I don't know
though Dave, I wouldn't be *too* hard on MFJ...I mean I know they
charge a lot for their stuff, but they did support you via customer
service with this... actually ALLOW tampering with the hardware (look at
companies like Apple..they would have voided that warranty faster than
you could have keyed SOS) Plus I know each should be checked.. but if
you don't hear a lot of people with the same complaint and problem, it
could just have been a one time mistake. I mean these are human beings
checking and assembling them, we all make mistakes. I just think that
it's a very good sign that the company really meant you half way, it was
repairable (meaning the parts they gave you were quality, just not
assembled correctly) Anyway Fine Business that you were able to get it
set up! Are you going to do a complete usage trial and test of the
Chameleon loop as well?
Yes, that's the plan.
Hi, David. An excellent video on the MFJ loop. I a now more inclined to get one. 73 Alan KZ6B
Holy smokes! Looking at the photo at 3:00, it looks like the stator plates in the upper right hand corner appear that they are not anywhere near centered with the rotor. Is that an optical illusion? That could severely limit maximum power handling, since it could easily arc over. The stator seems to be reasonably centered with the rotor plates in the foreground. It appears that the capacitor could stand a major adjustment in addition to the problem that you found.
Part of that is an optical illusion. I recentered everything and it works.
Not arcing? Each plate seems really not well spaced compared to the others
why did thay make so it do 80 meters to
Dave, Did you check for gain off the ends of the loop when you had it set up vertically? If I were to buy one the end gain on rotation would be why. From the omission I am assuming it isn't much. I would like to know.
I've never done any specific testing. I didn't find it terribly directional, though the radiation pattern drawings show a deep null on each side.
Dave, it looks like someone cut those rotor capacitor plates out with a hacksaw. Is that a video/photo artifact or distortion? The outside edges don't appear to be smooth arcs.
I have had a love/hate relationship with MFJ products over the years. The issues I've had with several products could also have been avoided if they had just checked to see if it worked properly. As a result, I look first to other manufacturers, MFJ being the last choice.
I really like the function this antennae theorectially provides, but I hear so many stories of MFJ quality issues, and since I live pretty much on the opposite end of the world I'm a bit wary of taking the plunge on one of these.
The cost of shipping something like this back and forth to Australia is a bit prohibitive - its really dissapointing that they sell their equipment as finished equipment though it seems from all the rerported quality issues that they are in reality semi assembled kits.
This is MFJ. It is what it is. I buy stuff from them, but I wouldn't put anything of theirs on a mast or tower without lots of testing first.
Enjoy your vids. I’m in an HOA out of necessity and considering the 1788 as an attic antenna. Just making sure, can you now cover the CW portion of 40?
Yes. Once I fixed the limit switches, it works fine.
check your hatch size, it wouldnt fit through my hatch
@@mattbw-G5MAT will do. I’m also considering an HOA Buster…uses rain gutters.
would be interesting to see how much power that capacitor could actually handle before acr over , I suspect the 150 watts radio output is on the conservative side ?
Maybe it is conservative, but note that any arcing will immediately change the SWR quite dramatically, and can thus damage a radio. I'd say stay within the rated limits.
English is not my first language.
i heard a phrase "to be backwatered" or "to be backquartered".
What's the right way and what does it mean?
I think it possibly may have been "backordered." It means you order something from a vendor, but they don't have it, so they put it on backorder. It means once they get it, then they will ship it to you.
glad you were able to fix it ! sadly low quality is the price we pay for chinese made stuff.
I'm not absolutely sure, but I think this is American-made. But, yes, the Chinese stuff pushes prices lower. I'm not aware of any Chinese loops for sale.
i was under the impression that MFJ was a chinese company, therefore all of their gear was chinese made.
just googled it, MFJ is in Starkville, Mississippi, I did not know that.
Very well stated.
There Quolity Control have to be Up Graded!
I bought their antenna tuner kit and had a similar issue with one of the air variable capacitors....the plates actually rubbed against each other when meshed. Very poor or non existent QC
Thinking of getting one but drop shipped at local HRO to test in their store b4 bringing home. Do you still own it? Does it tune on all or most of 40m band? I did own the 1786 but had no problem with that one. 73 Mark KK2L
I still on it and it works fine. It's up on the roof of the house, but it's not one of the antennas that I use frequently.
You wouldnt happen to want to put together a "here's how to clean and check your MFJ Mag Loop" video, would you? I've had mine since around 2003 and love it, but it desperately needs a cleaning inside, and either the remote tuner needs to be replaced or a component inside the antenna housing needs attention. Great videos!! 73 de Jeff, KF5KWO
I recently had to repair mine. Fixing one problem created another. I tried to use it at Field Day but we couldn't get it to work. I found out I'd moved something so it jammed on a screwhead and stopped working. I'd say just gently clean it out and see if there are any broken connections.
David Casler Thanks, I'll give it a go. I've got the -1786 (the 10-30MHz model) and I think it's a great antenna for my limited space and low-profile operation. 73 de Jeff, KF5KWO
personally I prefer the 1786 model, you lose a very lossy 40m loop and gain a high efficiency 12m and 10m loop.
So the problem was just crappy assembly and the warranty is written so the owner can fix the crappy products without voiding the warranty and don't have to bother MFJ? That's hilarious! I knew you could fix it Dave, I wasn't worried for a minute. You didn't mention if you fixed the poorly mounted capacitor plates but since you got a lemon I think you should have sent it back and got a good, properly built unit.
At 3:45 it appears as though the rotor and stator plate are touching or nearly so. Should there not be equidistant spacing? As built the voltage specification cannot be met. Also did you address the misalignment of the rotor plates shown at 2:00?
The rotor/stator misalignment at 3:45 is an optical illusion. The plates are properly spaced. And, yes, I did realign the rotor plates, although I didn't try for perfection. 73
Is there any indication that MFJ has fixed this problem? I am considering buying one of these or the fan box antenna.
I got mine quite some time ago (years). They're still selling them, so I suspect they got their problems fixed.
David,
Surely you can't use much power with this loop? Given that the capacitor is an open design and not a vacuum capacitor. It would really surprise me that it wouldn't start arcing at around 50 watt....
73
Paddy
It works well.
I won't bash MFJ except to say that you'd better open up whatever you buy and check for cold solder joints and loose mounting of the components. These issues are very common. If you are willing to do that you should be ok. I tend to buy used MFJ products. I figure that it bothers me less to fix something that I paid less for. There is always tons of MFJ products on eBay. Could it be that there are lots of dissatisfied customers unable/unwilling to repair the stuff? Well, I guess that their loss is my gain.
Sir David
the big mysterious question which hunt me since years is : Does the MFJ loop specially in 40 meter with it's 1 to 40 (diameter ratio for 40 Meter), would it give a performance ERP close to slandered Half wavelength dipole or (quarter wavelength with radials) (Vertically oriented)
So far on 20 meters it seems a fine antenna. 40 is not so good, but now that it's fixed, I'll be retesting.
OG, great video. Do you have a review of Hi Q antennas and how they preform
Just the videos on various mag loops.
Were you able to even up the cap plates when you adjusted the limiter arm?
Yes.
I had to fool around with mine as we'll