| N7XCZ |
Rating:  |
2024-02-27 | |
| works well on my small lot |
Time Owned: 0 to 3 months. |
I'm giving it a good review simply because it works on my small lot 100x60 and it was actually a 1793 I just did not add the stub kit and it shipped sooner and cheaper than any other vendors. I used the same Hustler 5BTV for 20 plus years mounted on the 2nd story of my home, it did great on 40 and 15 but was not really used on 10 or 20 I have a tri bander beam. I mostly used it for 40 meters though. But 80 meters was dismal I could not get long enough radials to lay on the roof. So I purchased this antenna new in box off of Ebay 197.00 shipped and it was brand new in the box Hi Hi as with other reviews I was missing nuts and screw's the ones used for the plates that hold capacity spokes, easy fix all the other hardware was present. assembly was pretty easy all the bolt hole's lined up on my unit and all the bolts were the correct length I did as others stated and drilled through the fiberglass mast for 80 meter coil and added a screw and nut . I pounded a 4 foot metal stake in the ground plumb with the facia on my roof line made a isolated bracket to hold the bottom tube snugly after antenna is lifted into place, I used both sets of guys as well. I know it's not the place a vertical should be away from other objects with a perfect radial system but I don't have the real estate for the ideal setup so I used the house for more support Reno gets some very strong winds. I am still laying down radials and also will pound in a 8 foot ground rod and hook base to ground. I got lucky I did 6 spokes uncut and I get 1.3.1 at 3.573 and it covers the CW portion very well, That's right were I wanted 80 to be. But on 40 I get 2.0 across the entire band maybe a small dip at the top end of the band to 1.8
My antenna tuner resolves it but odd that I got opposite results of other users most stated very good SWR on 40 but trimming required for good SWR on 80.
Performance of antenna I think is good as well.
I have already worked more 80 meter stations during the last ARRL CW DX contest than I ever have and get good reports on 40 I am running a Yaesu FTDX 5000 and an Ameritron AL80B and the 1792 does not have any problems with 500 watts FT8 900 watts CW and 900 watts SSB. I will put down as many more radials a I can cut to 66 feet 33 feet and 16 feet. I also will add a receive loop under the 2nd story eve I can get about 100 feet of wire up there I might even add some coils to the loop with a preamp and use the RX antenna input on the 5000 for some listening help. It Has been holding up well in the wind so far 30 to 40 mph gust. over all I am pleased with my purchase and the
MFJ-1792. I will post pics to the Zed soon |
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| KO7SS |
Rating: |
2020-09-22 | |
| Very good design, does the job! |
Time Owned: 0 to 3 months. |
I just needed a full time skimmer antenna and back up 40/80 RTTY contest antenna. My main 40/80 antenna is an OCF dipole, but many times it is too windy here to put the 55' tower all the way up. The beam on the tower does OK at 22', but the OCF is unusable.
I think with MFJ you are buying the design and aluminum tubing, but you will need a drill and a trip to the hardware store.
The antenna arrived without the aluminum 1/8" diameter spokes for the top. I called and they picked up on the 2nd ring, took my name and address, and without a question I had the spokes 3 days later.
Some of the aluminum had to be drilled and a few washers and nuts had to be bought at the hardware store but it was all obvious what needed to be done.
The vertical is sitting over 36 X 65'-75' radials and is 1:1 SWR on 40M, the base impedance matching coil seems fine with 1200W RTTY.
On 80M the SWR from 3570-3600 is |
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| W9DZ |
Rating: |
2019-12-28 | |
| Good quality and performance - docs need updating |
Time Owned: 0 to 3 months. |
I purchased the MFJ-1792 in April of 2019 but didn't get it installed until November. I bought it from DX Engineering as I had unused balance on a gift card. The list price of the antenna is now $220 plus an extra $10 for shipping (oversize) and sales tax for your state. Shop around and you can find a better price.
I gave it a rating of 4 out of 5 due to the fact that I was missing the addendum detailing engineering changes. Some reviews mention a missing top hat spoke. The original mounting hub was designed for 6 spokes. The mounting has been changed to two metal plates and the spokes are sandwiched between them. It will accommodate 8 spokes but the docs still state the top hat is 6 spokes and 7 were actually shipped. They are still enclosing a bolt for the hinge that is too short. I picked up a longer one at Ace hardware and also bought Nylok 1/4-20 stainless nuts to avoid having to use a lock washer at every joint.
My antenna is ground mounted and I am using sixteen 32 foot radials. I also drove an 8' copper plated ground rod at the base. I haven't had any tuning problems. The SWR on 40M never goes above 1:4 to 1 and is flat at 7.2 MHz. Initial adjustment of the capacity hat can be frustrating if you don’t have access to an antenna analyzer, noise bridge or dip meter. With full length capacity hat spokes my antenna resonates at 3.3 MHz, well below the bottom of the band. Since most modern transceivers will not transmit outside the bands, you won’t be able to determine your starting frequency with an SWR meter. I cut 3" off each spoke and resonance moved up to 3.5 MHz. I have now trimmed a total of 4 inches from all 8 spokes and minimum SWR is 1.2 to one at 3.550 MHz. 2.0 to 1 bandwidth is 80 KHz. Resonate frequency increases 10 KHz for each inch of spoke you remove. Cut 1 inch from seven spokes and you move 70 KHz. If you add the eighth spoke, which isn't included, the frequency moves a little over 8 KHz per inch removed. I have installed guy lines at two levels and am using 4 sets of guys as opposed to the usual 3. The guy rings will accommodate either 3 or four sets of guys. I'm using 3/32" Dacron guy lines.
If my review was based on performance and quality alone I would have given the MFJ-1792 a 5.
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|
| KC9ADB |
Rating: |
2019-11-15 | |
| Not recommended unless you are looking for a "project". |
Time Owned: 0 to 3 months. |
Going into this, I accepted the fact that most any item from MFJ would be a "project" and would required modification, chasing missing parts or possibly replacing poorly made parts. I'm not an MFJ basher, but we get what we pay for. Sadly, their reputation exists for a reason and was substantiated with the 1792. I do have other higher quality vertical antennas from companies such as Zero 5, GAP, etc. and the MFJ 1792 pales in comparison.
IF there's one bright spot in this project, it's the aluminum tubing, which is acceptable, but not by much. A special note of caution is the 1792 MUST be guyed at two levels. (This vertical will not stand on its own and will likely fold and collapse with only one guy point). Even with two guy points it can still seem like erecting a wet noodle. There are two guy rings included and it's highly recommended to use both per the instructions. As a side note, the instructions are oddly written but most people should be able to decipher their intent. Most of the parts related components are acceptable including the hose clamps, so not all is lost, unless they forget to include them.
The top hat/coil portion appears like an after thought and I still can't get it tuned to any portion of 75/80 meters. I expected very narrow bandwidth on the general portion of 80m, but can't find it. Of course it would help if MFJ would include "all of the top hat spokes" and not jerk me around when I was trying to get warranty replacements. Thanks MFJ for waiting until it's cold and snowing to send me parts you didn't included in the original box.
The mounting base appears somewhat undersized for the amount of load this vertical is producing, but a trip to the hardware store and larger u-bolts is highly recommended. Raising this vertical really requires at least two adults, but of course I raised it 100% on my own, but that's just me.
The feed point and loading coil at the base are not 1000 watt rated regardless of what the MFJ specs say. (The initial SWR was below 1:7 on 40 meters but I had to gut it and rebuild it using better components). Now 40m is 1:4 across the band and no problem so far, not at the feed point anyway. Please note, like most verticals, you must use either a radial field or in my case, above ground elevated counterpoise for each band at proper length. With out them, SWR is sky high of course.
So in conclusion, the 40m portion of the 1792 will perform as designed, but even a vertical wire of the same length will more or less do the same thing. Receive strength is solid and the receive noise is acceptable for my QTH. Operating with the AL 80-b and the low VSWR does make breaking thru DX pile ups is easy, but no more so than any of my other verticals. Now I have overkill on 40m and still no 75/80 without severe tuner/matching loss.
The top hat portion of this antenna seriously needs redesigned or just omitted from the antenna altogether and I'm thinking of how I can still make 80m work for the 1792. I will bring this wet noodle down in the Spring to modify the top hat portion or maybe just remove it.
If I go to the trouble of lowering it, I will probably just replace it with a Butternut or something else. It's really too bad because the design concept is correct. The execution of the MFJ 1792 just leaves me thinking I wasted money when I first had plans for an 80m End Fed Zepp at tree top levels.
I really wanted to think that MFJ was getting it's act together, but I was let down. The phone and on-line interaction with MFJ left me wanting......wanting something else. |
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| NB4M |
Rating: |
2015-12-07 | |
| Good antenna - awful support |
Time Owned: 0 to 3 months. |
1. I needed an 80m vertical within a week for the CQWW CW.
2. I purchased the MFJ-1792 from R&L Electronics, in that I knew the antenna would get to me on time.
3. The antenna arrived in one day (OH to TN). Thanks R&L.
Opening the box, I find a poorly written instruction manual with addendums stapled front and rear. I also find the parts list incomplete - missing all of the capacitance screws, two of the capacitance elements, and (as mentioned in a previous review) the bolt for the lower tilt-over mast is too short or totally missing. A pitiful and common occurrence with MFJ from all I read.
A one hour ride to the local hardware and back, I am finally able to begin the build. Minus the two capacitance elements.
Using aluminum contact grease, I find the antenna is very simple to construct, goes together well and is easily erected in an hour or so (about the time it took to retrieve all of the missing parts).
Note; A simple improvement is to use a 1/4" ring terminal and secure the feed point under the lower mast bolt. Simple, makes sense and a much better connection rather than slipping it under a hose clamp as direct by MFJ.
Also mentioned in previous reviews and by instruction, the 40 meter resonance point is 6.5 mHz. Why in the world would you design and instruct the antenna for well below the lowest portion of the 40 meter amateur band?
On to 80m, with some disgust. Given the missing elements are critical to the antenna resonance (which I knew before construction) my build is most efficient at 3.8 mHz. Quite challenging for the CQWW CW, but with time of the essence, decided to give it a go.
Four each quarter-wave 80m radials, equally spaced and we are ready.
To my surprise, the antenna performed very well and managed high power over the entire length of the contest (with tuner assistance). DX entities were satisfactory, considering the compromised size, with 61 countries logged.
Now let's try to get the missing elements from MFJ. Impossible you say? You are right!
Several customer request tickets and calls to MFJ, no luck, and I'm not even sure the persons (more than one) I spoke with understood anything about antennas. Left voice mail for others, but never received a return call. Pathetic.
*R&L Electronics responded to my first inquiry and said they would get the elements for me. I understand they are not the obligated manufacturer and appreciate their support.
So, if you want a reasonably priced/good performing shortened 40/80 meter vertical, this may be the one for you. Just don't expect the miserable bunch at MFJ to provide all of the necessary components or care.
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|
| PE1PYC |
Rating: |
2009-07-31 | |
| Great Antenna but.... |
Time Owned: 3 to 6 months. |
I own the 1792 for about 4 months now and all i can say is that it works great from the back of my small garden.
Only thing you have to keep in mind is that you reli need to guy it, it wont come down with the first gale but it does bend if you dont watch out.
Just put down AT LEAST 4 33ft radials or a couple of elevated radials, and let he dx come in!
BTW, QC at MFJ must improve because i also had to drill a couple of holes myself.....
Great great value for the $$$ |
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| KD0BVK |
Rating: |
2008-09-14 | |
| Great value, some difficulties |
Time Owned: 6 to 12 months. |
I mounted the 1793 (same as 1792 but with a 20m radiator included on fiberglass offsets) on a rooftop tripod (20' up) on a ranch style house with three pairs of guy ropes. It has buckled twice in straight line winds, always on the same section, so it must have had a defective tube. After cutting about 6' out of that section it has stood up to the severe weather since, though of course it is now de-tuned on 40 meters.
Performance is acceptable on 80, 40 (with tuner now), 30 (tuner) and 20 meters. Noisy as heck but that's no defect in the antenna, that's just how verticals are in urban environments.
As happened to others it arrived missing parts, and MFJ sent a lot of extra parts that I didn't ask for (including some that obviously didn't belong to this antenna hi hi) but that's alright. In the end I had everything I needed without having to buy any extra hardware, waited about 2 weeks.
Overall I'm ok with the purchase 6 months on, not bad at all for the money. Needs much better quality control though, so one point less for that.
73
ai1p |
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| K2CG |
Rating: |
2008-05-10 | |
| I am pleased and surprised |
Time Owned: 3 to 6 months. |
I have bought a lot of MFJ equipment in the past so my expectations were not too high. Almost everything I have purchased from MFJ previously required a small bolt or screw and or required either fixing a solder joint or removing loose pieces of solder floating around inside with components. I figured with MFJ’s Guarantee and the very reasonable price it was worth a gamble.
Before assembly I completed an inventory, I was missing a few bolts and one large “U” bolt assembly. I notified MFJ and the missing parts arrived 45 days later, even then some of the parts they shipped were not the ones I told them I was missing. I bought the missing parts from Home Depot and assembled the antenna after waiting one week for the parts to arrive. I knew from past experience that continued correspondence would be an exercise in frustration and the additional cost was minimal.
I was initially not impressed with the thickness of the aluminum tubing; however during the assembly it became apparent that the tubing is very good quality. I have had the antenna up about 4 months now and it has survived several very high wind storms 40-60 MPH winds and one CAT 4 Tornado that passed one half mile from my house, http://www.clarksvilleonline.com/2008/05/03/tornado-strikes-south-clarksville-fairgrounds-pavilion-demolished/ the antenna has held up and demonstrated very nice performance. The 80M Coil and Top Hat was not that heavy but when raising the antenna up from the horizontal to the vertical position that little weight was apparent. Had the Mast tubing been thicker, raising the antenna could have been an even bigger challenge. I followed the guying recommendations and the antenna has handled the winds nicely.
I made some small modifications based on observations from Bill Zurilla, NZ5N.
First, step 18 on page 9 of the manual calls for, and my antenna came with, a 1/4 - 20 x 1 3/4" bolt to secure the fiberglass rod to the base mount. There is no way that a 1 3/4" bolt will work. I replaced it with a 2 1/2" bolt to get the job done.
Second, with respect to step 29 on page 11 of the manual, the 10-32 x 1 3/4" bolt goes through Tube 6 but does not go through the fiberglass rod around which the 80 meter loading coil and the capacity hat are attached. I drilled a hole through the bottom of the fiberglass rod. Completed the assembly with the bolt threaded through Tube 6 and securing the Fiberglass rod to eliminate any possibility of the Top Hat rotation during high winds and possibly placing stress on the connector wire of the 80M coil.
Next, I replaced the connectors on the 80M coil with a larger connector to permit a more solid connection under the Tube 6 Bolt as opposed to placing the original connector under the hose clamp. I covered all connectors with Heat-Shrink wrap.
I used “Penetrox” every place the tubes overlapped and on all connections. I used “Loctite” on all bolts and nuts.
I replace the top wire on the matching unit, again to permit the wire to connect under the bottom bolt rather than under the bottom hose clamp.
I used a DX Engineering Radial plate for the Radials. I buried twenty 35’ radials. I checked the antenna for resonance with my MFH-269 and was very pleased with 1:1.1 on the CW portions of the bands on 80M, 40M and 30M. The antenna is connected to my radio with 120’ of “Bury Flex” COAX that is buried in a PVC pipe.
During regular operation my K2 antenna matching unit has shown 1:1.0 on 80, 40, and 20 Meters. A quick menu check shows that the match was possible without using any CAPS of COILS from the Unit. I have also observed very reasonable matches on 30, 17, 15, 12 and 10 between 1:1.1 to 1:1.2.
I have been able to make some very nice DX contacts to Central and South America. I have also been able to hear stations in Japan, Eastern Europe and Africa that I could not hear on my Horizontal Loop that is up 45’.
Overall given the price, quality and performance of the MFJ-1793 I am pleased.
K2CG Chuck Gehring
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|
| G8KSM |
Rating: |
2008-02-26 | |
| Modded MFJ1793 is FB on DX |
Time Owned: more than 12 months. |
I originally purchased this as the 1793 model that has the optional 20m radiator and operated it for a short time with a good earth and was impressed by the results. I quickly added 8-off 10m radials that comprised 8mm copper microbore heating tubing about 1-2 inches below the grass and got a huge improvement in performance, especially on 40m. This antenna is essentially a quarter-wave 40m vertical, so it needs a good earth and once its got that, you can throw away the ATU and works some real DX, on 40, that is.
80m also gave good results and the bandwidth was exactly as predicted - trouble is, the low-angle radiation means that it's not really very good with stations up to around 150 miles away, but it is very, very good with mobiles - I consistently get much better reports to/from mobiles on 80m than people using conventional dipoles etc.
20m operation was OK, but nothing special and certainly not what I'd call 'DX'y' but then what do you expect from a quarter wave ???
I operated this antenna for about 6 months from my old QTH with better-than-expected results but when I moved to my present location I decided to do some mods that I think really improve the performance. Firstly, I was never really very impressed with the 20m performance - the SWR bandwidth was surprisingly narrow and the 20m element was very flimsy; a good strong wind often wrapped the element around the main mast or whipped it into a distoted shape. Having said that, the main mast with top-loading coil / capacity-hat, although weak-and-weebly, had survived a couple of gales without damage, but I put this down mainly to the use of kevlar guys.
I threw away the old 20m radiator and made-up a new one using 10mm diameter aluminium tubing with a new bottom bracket and three insulated spacers at approx. 1m intervals up the mast, all made out of bits from the local B&Q hardware department.This new 20m element provides a wider bandwidth than the old one although not quite the full 350kHz, but good enough, anyway. As I'd got some tubing left over, I decided to have a go at adding a 17m radiator as well, in the same format as the 20m one and this pretty-much covers the whole band at an acceptable SWR. This gives me very good coverage of 4 bands without the need for an ATU, unless I want to go lower on 80m. Again, 8 radials were installed under the grass, using microbore copper and the whole thing cabled back to the rig with about 30m of Westflex 103 coax.
My very first QSO was with a VK on 40m and he gave me 57. This was followed over the next few months with a very encouraging log full of DX on 40 and 80 with occasional forays to 20 and 17, where SWR under 1.2:1 is available over the majority of the bands. 40m coverage is for the full 200kHz without any significant SWR and I've set my 80m up for the top end of the band where I get unde 1.5:1 over the range 3.73-3.8 Mhz, which is just what I wanted. An unexpected bonus is that, although I need an ATU to match it, I get really good results on 30m as well and have done about 120 countries in 6 months without really trying.
I really recommend this antenna - sure, the main mast is a bit flimsy and you really do need to take some care putting it up. In particular, you really need to use good-quality lightweight guys and the guy rings need to have some additional padding / tape under them to reduce the chafing on the main mast. Most important is to have a decent set of radials, and here it is size of the conductors that matters, not necessarily the quantity. Please, please, use decent waterproofing on all connections and joints - dont just leave bare or use cheap PVC tape - it's not worth it in the long run. The only other thing I might consider changing is the method of holding the six capacity hat rods - these are secured to an aluminium ring using stainless screws and whilst I've had absolutely no problem with them, I'm just not totally convinced that continual visits from birds using it as a roost might not eventually take its toll.
In the last 12 months we've had a significant number of nasty gales and we have a fairly exposed location high-up on the moors and the aerial has hardly batted an eyelid. The top guys are fairly well down the mast, and when the wind is really hammering, the top section does whip about a bit so I'll be checking the effect of the guy ring carefully before finally deciding, however, this is an antenna that is simple enough to replace bits if needs-be and easy-enough to tune-up that I can see me keeping it for a very long time. |
|
| ZS1TTZ |
Rating: |
2007-12-05 | |
| A good product |
Time Owned: 0 to 3 months. |
My main concern before assembling and installing this antenna was, how is it going to stand up to to the kind of weather we get here in the Cape?, extremely high winds are not infrequent.
I didn't have to wait long to find out, by day two quite a severe storm started up. Driving home from the office I was alarmed to observe a fellow ham's crank up tower "cranked down", the first time I had ever seen him do this, so I almost daren't look up when I turned into my street, but look up I did and was relieved to see it still standing.
I checked and adjusted the guy tensions, then sat outside, sheltered on the patio and observed it for about an hour, the wind was strong with severe gusts, it was moving about "quite a bit" at the top, seeming to pivot about the top guy ring and corresponding slight bending midway between the two guy rings.
When all was calm again, albeit for only a brief period, everything was still dead straight, and over the next two weeks it was subjected to many more similar batterings, all with no ill effect, and now, apart from regular guy inspections I don't worry about it at all.
So, it passed that test, and the other test it passed is that the xyl thinks it looks great !!
As for performance, same as everybody else has said, it works very well, dx on 40m is definitely easier than with my wire doublet, and the top loading on 80m is a definite plus over most of the competition. On 80m I tuned for the bottom end, being a CW operator, but using a Kenwood hybrid I can still tune the phone section with the loading cap just about fully open, without the need for an external tuner.
I think if I had attempted to build something similar myself, and saw it swaying around like that in the first storm, my first instinct would have been to call for help and get it on the ground asap, so there's certainly a "peace of mind" factor included in purchasing an established product, coupled with the hassle-free assembly benefits of buying a kit, everything you need is in the box, it was fun to assemble and rewarding in performance, it's going to score well at this qth.
If I have one criticism it would be with the instruction manual, where it states that one set of guys is the minumum, I would cross that out, two sets of guy rings are provided so you might as well use them, two sets of guys are the minumum, this review might well have been completely different had I just installed one set.
73 de Adrian / ZS1TTZ |
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