MFJ-1835H Cobweb antenna review (high power version 1.5kW)

It is rather pointless to compare a rather inefficient trapped vertical (probably with no ground plane other than the metallic part of your RV, right?) to a highly efficient (@97%) horizontal antenna that has no lossy traps or that requires a ground plane to begin with (practically apples to oranges). FWIW and while I don't know exactly, I suspect that 500 watts into a cobweb at 30 feet or more would equate to 1500 watts into a trap vertical as far as field strength goes. The horizontal cobweb will have ground gain unlike verticals, too which is just one part of the multi-faceted reason why many consider them to be one of the best-kept secrets in the antenna world around.

While I haven't tried either MFJ iteration of G3TXQ's single-wire elements version I did build one from scratch with QRO in mind---and it performed very well at 35 feet above ground. My final SWR on all the bands ranged from 1.2 to 1.4>1 and this version has an impedance of 12 ohms which is why a 1:4 balun must be used.

While cobwebs of any type are notoriously tricky to tune because one must usually tune closer to ground before erecting and the elements are also close together---but once properly adjusted they're "good to go" and only require a single feedline and single support. No rotator is needed as the antenna achieves a true omnidirectional pattern---which is the only similarity between a vertical monopole and this horizontal wire antenna that consists of 5 full-size nested dipoles bent into a compact square that I can think of.

While I wouldn't want to assemble one in limited time under the pressure of Field Day I suppose one of these compact antennas is small enough to transport already assembled to another location for use in such events; just add mast and reconnect the coax. Because no rotator is needed a lot of weight is saved and this allows one to mount it higher more easily, too.

Judging from Pascal's excellent video I'd say these QRO MFJ cobwebs are fairly well designed but a lacking a bit of durability in certain areas as others have mentioned. I'd probably install a sturdier balun box and use sturdier element wire to further improve one for starters (but then again I'd sooner build one from scratch anyway; it's not rocket science involved here). For those who enjoy crafting their own skyhooks, G3TXQ has a tutorial on building them complete with the 1:4 balun on his web site (and it's quite easy to substitute beefier FT-240 toroids for more power handling than his UK-limit version).

 

I started construction about 11:00 AM 3 hours to do it right all band but 17 meters tuned easily had play with 17 to get it in band.
All parts were in box and there was a few Extra screws and bolts. Antenna is well made EXCEPT for the wires bet they will not last the winter
I would gladly pay extra for better wire with plastic covering and eyes crimped on both ends. you must have an antenna analyzer to tune the antenna. I will put it up at 25 feet tomorrow and run some tests in CW/SSB, and digital 20 meters most likely .

 

Hi Pat, for the antenna you mention can you give me the Mosley model number? You can watch my French version video for practice, hihi, it's available on my YouTube channel. 73 Pascal VA2PV

 

HI Pascal
I have one of the Mosley Mini-31A rotatable dipole the 2 element is the Mini-32A mine has lasted through 2 winters here in Northern MN

 

It is the Mini 33AW I bought it used 4 years old, from a guy in Texas. We had some snow and some ice here last winter and no problems. Easy to assemble, turning it with a CD45. Pretty flat across all bands. I have not installed the WARC dipole yet plan to do that after the summer when the ARC police have gotten used to it. I replaced a TET 23M 2 element that had been up for some 30 years. I wanted a bit more gain and the lower profile the Mosley gives me. I live 30 miles east of the Blue Ridge mountains by Dulles Airport and wind is more of an issue here and it has done well. They really had a fit when I put a full size Mosley Classic 33 with a 30 ft boom and 29 ft elements but man was it fun for a week.

Pat

 

I whould like to test one, but the price is higher than i expected it to be for those kind of antennas...The materials can not simply cost as high as 200+ $ !!

 

This seams like a good place to ask this question?
I have been inactive for at least a couple of decades, but in the mid 70's I would not have let a piece of MFJ equipment into my shack.
The ones that I encountered at that time were just junk and the cabinets/cases were so sharp it would fillet (verb) your arm if you brushed against one.
That being said I had a 'Versa Tuner 2' given to me and it works great, though it still has that cheap look but seems much better than they once were.

My question is; Is MFJ better now overall than it used to be, can you buy their products sight unseen without concern about it being junk?
This is not a dig towards MFJ, just a question... Thanks...

 

I was actually referring to the construction and not the performance. True. It has been said vertical antennas are equally poor in all directions BUT regardless, my vertical suites my needs and 76 country contacts is testimonial enough for me.

 

The antenna is a horizontally polarized and omni-directional with ~2dBi. It has good ears in all directions, and the OM who owns it has recently had 5-5 to 5-7 QSOs with Guinea-Bissau and Vanuatu on 100 watts from Long Island. I'm sure the matchbox is a compromise, but there are no disappointments with the antenna's effectiveness-to-price ratio. It's also worked very well for him in SSB contests. What's nice about the omni-pattern is that you don't have to wait for the rotator to find signals...they come in from all directions at once. It's also inconspicuous...it doesn't look that much different from an HDTV mast at first glance from the street.

I would not call it a portable antenna as-is...but there is no reason why a little bit of Ham ingenuity couldn't make it so for field day. Build it, get it tuned, and then think about how to keep it tuned for disassembly and reassembly. Keep an analyzer at hand...it's invaluable.

 

Yes CobWebb, I am also very satified with them. I build them but like the origin with the delta-match (2 - wire cables)

 

In my personal experience most of their products on the outside still look like I home brewed them, with sharp edges, burs, poorly fitting cabinets, stripped screw holes that don't line up correctly and poor paint finish. Internally I still find poor and/or no soldering of connections, poor assembly and shoddy parts, really bad QC from seemingly unskilled labor.

But I've bought lot's of gear from them in the past 25 years because they have always come up with unique and neat gear not seen manufactured elsewhere. Very recently I purchased an MFJ-259C antenna analyzer package with the extra do dads, some parts were missing and some of the the rechargeable batteries were defective. But I'm a good enough technician to fix their stuff and not have to ship it back. In 2016 I bought MFJ-974HB and MFJ-986 antenna tuners as well as an Ameritron AL-80B amplifier with the same kinds of issues I already mentioned above and I fixed everything.

But I have to say that the two MFJ antenna tuners had a better matching range than the equivalent Palstar units that coast many 100's more.

And Mr Jue has saved allot of hamateur radio legacy brand names that otherwise would be extinct, so I'll keep buying gear from MFJ and just expect that I'll more than likely have to fix it.

 

Avoir?

 

Thank you for that update...

 

I have had a G3TPW manufactured version for over 10yrs now. It has been up and down several times due to moving and never failed me yet. Yes it is starting to weather and yes, it doesn't like the rain that much.....but it has served me well and was the reason for me returning to Radio after many years away. I even recommended it to my lad and, like me with a small garden, we have managed to work all 4 corners of the globe. I usually try to stay around the 100W mark but have occasionally put 600W into it and it doesn't bat an eyelid. So, for those with small footprint to play with....you won't be disappointed if you make the choice.

 

I have modified my MFJ-1835 for quick assembly and compact transportation.
https://docs.google.com/document/d/1-cUTUINt9bZcIxljA043OdaqpShsLvHYB-yica11-SA/edit?usp=sharing.

I used it at FD this year at 18 ft and it worked well.