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Reviews For: MFJ 1836H

Category: Antennas: HF: Verticals; Wire; Loop

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Review Summary For : MFJ 1836H
Reviews: 4MSRP: 299.00
Description:
20-6 meter cobweb
Product is in production
More Info:
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0043
VK2TDN Rating: 2023-10-08
Very pleased with construction ease and performance Time Owned: 0 to 3 months.
I purchased the 1836H version, not because I needed the higher power capability, but because several had said that it was a stronger construction than the 1836 low power version.

I found that the construction was straight forward. It took some 5 hours to assemble it after confirming all the parts in the kit were present and accounted for. Nicely, there was a small excess of screws, nuts and washers.
The following day I did the tuning up, using a NanoVNA V2 PLUS4 at the feedpoint. Started at 20m and worked my way up to the 6m section.
All dipole wires were longer than necessary, which was good, and the VNA made it easy to see where the initial resonant point was and then trim the wires from there.
Someone else commented on the inches vs metric difference - this is really not a fair gripe. Even here, in Australia, we use metric but most tape measures/ rulers have imperial on them as well, so dead easy to assemble and tune using the imperial(inches) as used in the manual.
I tuned for approx. the middle of the SSB portions of each of the bands. There was very little effect of one dipole on the adjacent ones and the individual dipoles required very little fine retuning.

Have made a bunch of QSO's on 20, 17, 15 and 10 metre bands with the antenna only around 4 metres off the ground. It will finally go to 6.5 metres up.

All in all, I am very pleased and highly recommend it to anyone with limited antenna space, as in my case.
cheers
Dave, VK2TDN
PA3FPZ Rating: 2021-05-10
MFJ-1836 Cobweb 300 Watt version Time Owned: 0 to 3 months.
Looking for a cobweb antenna and not wanting to build one myself, it came down to choosing between an Italian build, German build or the MFJ build cobweb. As the MFJ had such good reviews, the choice seemed easy and the MFJ was ordered.
The MFJ-1836 came neatly packaged and well sorted into separate plastic bags. Then to my surprise, all the measurements were described in inches only. Not used to inches, a conversion to metric was necessary to make any sense to building the antenna. Does MFJ not sell outside the USA? Why don’t they give dual measurements?

Then while building the antenna, surprise number two, my metric spanners did not fit properly. Be aware all the materials are non-metric. Also the build is very fiddly, it takes a lot more time than you think to put everything together. I thought: “start in the morning, have it on the roof by the afternoon” no way!

While assembling the antenna I noticed a rattle inside the Balun. On opening the balun, surprise number three, or better said pure frustration. The soldering was very poor and one of the contact lugs was loose. I had to resolder the whole lot. But worse than that, there was absolutely no weather proofing inside the box. I expected the insides to be completely emerged in epoxy, or an equivalent. But not even a seal to the box cover was present and the coax braid was wide open to the elements. Yes two holes are drilled in the bottom of the box to let the moister out, but at least MFJ could have protected the balun itself from the elements. After resoldering the balun, weatherproofing the inside, leaving the breathing holes open and making a seal to the box cover, I finally started to open wire packs.

Then surprise number four, the wires are made from soft thinned copper wire. I expected at least hard drawn copper, or copper-bronze wire. Will this last? My others wire antennas are all over 25 years old and still OK. Also soft copper sags over time, will it detune? When you tighten the screws, soft copper quickly snaps. My frustration with the build quality mounted even more when I discovered the contact lugs were badly soldered. So I had to redo them all. Determent to get the antenna build, I started the assembly again.

Then surprise, by now frustration, number five. The wire packs had mismatched lengths per bag. The 10 meter wires were too long, the 15 meters too short, 12 and 17 meters had unequal lengths per pack. This made me undo all the wires once more and sort out the wires to their designated frequencies.

By now the day was lost and building the antenna turned into total frustration. How can MFJ sell such a poor quality product? The materials ooze total disinterest to its user, is this the American way of making a quick dollar? How can it get such good reviews?

Another weekend loomed and finally something positive, it does tune up. Using an analyser it took just under two hours to get it resonant. The setup was on a small mast 4 meters off the ground. All the wires interact with each other, so get it tuned just under the desired frequency. Making it resonant starting from the outside going inwards, as described in the manual, is not as good idea. After the described procedure, a final check revealed all the bands were out of tune. Most of them were resonant too high in frequency. The resonant frequency is also very narrow, overshooting apparently happens quickly. Luckily I wrapped some extra wire around the radiators, so retuning was possible. Bad weather kept the antenna from going onto the roof for some weekends. The cobweb stayed on a small pole waiting for a good forecast.

Then getting ready to put the cobweb onto the roof, surprise number six. A final check at the 4 meters high test mast revealed the cobweb was out of tune again. The instructions were specific not to over tighten the wires, but not to leave the wires too loose. All the soft copper wires displayed some form of sagging and the resonant frequencies were all too low. This means retuning will be necessary in the future, as the soft copper will most definitely stretch again. All because MFJ opted for soft copper and not hard-drawn, of copper-bronze wires.

Determent to get at least one season out of this abomination of an antenna, it went on the roof anyway. Then irritation number seven, the mast clamps do not fit a standard metric mast! They are just a fraction to tight, another inch to metric problem. Even more determent, the clamps were bend in an O-shape to gain an extra millimetre of clearance and now it sits on the roof doing its job. For how long? Your guess is as good as mine!

If you are looking for maximum frustration, enjoy working non-metric, are happy with waisted hours for nothing and terrible build quality does not concern you, this antenna is for you.
N7WR Rating: 2020-11-13
20-6 meter cobweb Time Owned: 6 to 12 months.
With a move last year to a new QTH and downsizing my station I have been using a vertical antenna. It has been satisfactory but like most verticals it picks up a lot of noise. I am not in a position to put up a tower and yagis like I used to have but I wanted a horizontally polarized, omni directional antenna. Given its reasonable price I decided to try the MFJ 1836 H (high power) since I do run a 500 watt amp from time to time. Next spring it will go up on a 36 foot mast but for the moment is resting at 22 feet in a temporary installation.
MFJ included ALL of the parts including quite a few extra nuts, bolts and washers. The assembly manual is reasonable clear but having built many antennas over my 62 years as a ham the few not so easily figured out parts of the manual were easy enough to work around.

The quality of the materials was very OK except for the wire from which the dipoles are constructed. A little thin but could easily be replaced with some #14 stranded copper wire. Assembly from start to finish took a little over an hour. Tuning each dipole was aided by an antenna analyzer and was done on a test mast at 6 feet AGL. When I put it up at 22 feet the SWR curve on several bands changed but because this antenna weighs next to nothing (8#) I was able to bring it back down and make some adjustments. Long story short the SWR on each band at my chosen frequency is 1:1 and for the type of antenna it is the bandwidth is surprisingly good.
The real plus with this antenna, being horizontally polarized, is that it is much more quiet (noise wise) than my vertical. Stations that I can tell are in there on my vertical (but hard to understand because of noise) are easy (and almost noise free) copy on the cobweb.

Haven't had it up long and, as I said it will go higher next spring, BUT I have easily made DX contacts with it running no more than 500 watts. And I get good signal reports back. A few times I have done an A/B test between this antenna and my vertical. The cobweb has always gotten a better signal report.

This is a small, light weight, omni directional, horizontally polarized antenna that would easily fit in the attic of many residences. May be an ideal solution to HOA restrictions. For those running barefoot the MFJ 1835 has the same coverage and handles 150 watts for a little less $$. I rated it good based on quality and performance. A slightly better manual and heavier wire for the dipoles would have gotten it a "great".

Update: Having now had the antenna in operation for awhile I have a couple of additional comments. My overall rating stays the same. The antenna survived what for this area was a very mild winter and has also survived some pretty strong winds.
The antenna is rated at 1500 watts and I have never run more than 600 watts into it. However I noticed that it was not working at all on 15 meters so I looked up at it and saw the wires dangling from near the insulator for that band. I pulled the antenna down and found that the insulator had burned through and that ALL of the insulators (all bands) showed signs of arcing. That should not be the case with only 600 watts to the antenna. I "rebuilt" the antenna using heavier duty pieces of PVC as replacements for the very thin insulators provided by MFJ. Adds a little weight but not much.
Here is another update (11/13/2020) and it results in my rating being downgraded quite a bit. The antenna is still up and for the first time since I put it up we have had snow with very minor ice loading. The antenna with any ice loading at all de-tunes badly. I am seriously thinking of replacing this antenna with something else next spring.
W0DKM Rating: 2020-03-27
Very Good Antenna Time Owned: 3 to 6 months.
I have been using Dipoles and verticals for years.
But had problems running power over 100 watts.
And Power line noise. Small lot and Power lines
in the air all over. Using amplifier at 600 watts feed
back through lamps and wiring in the house.

This Cobweb antenna is well made, and easy to assemble. Tuning was a breeze. Light weight.
Good coloring of parts. Hard to notice it at 30 foot high.
Handles 600 watts with no other issues.
The design is Great.

I used it in a contest, and it worked anyone I heard.

Very happy.