Review of the MFJ-1835 Cobweb Antenna (#71)
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- Опубліковано 24 лис 2024
- Here's a review of the MFJ-1835H (high power) cobweb antenna. It has a very small footprint and can be a great stealth antenna. I found myself really liking it. Join me for unboxing, assembly, and testing. If you have limited space for an HF antenna, this may be one to look at. Subscribe: / davidcasler . Ask Dave Playlist: goo.gl/inaQeB. Tip Jar: ke0og.net/tip-jar
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These are incredibly comprehensive videos. Your attention to detail and relating of your experiences with your equipment is wonderful. I feel like I hear little ham radio 'pearls' everywhere listening to your videos.
Reminds me of my mom's old umbrella clothesline back in the 1950's !
That's what my wife said!
whether you make them from scratch or you buy a kit, these things are an absolute pain in the posterior to assemble !
They perform reasonable well. I made mine so it could be collapsed (so it would fit in a van) That eventually worked but a 'fun' project it was not !
73
Paddy
I love the commentary during the staple removal and tape cutting.
Thanks
Good to know it has less noise than a vertical, something that is important for people in cities and suburbs. Being dipoles I imagine getting it up higher would significantly improve performance.
I suspect so. I mounted it low because it's billed as a "stealth" antenna. Now that I've done the review, I plan to mount it on my roof.
Its a standard full size dipole but with the ends coming back close to each other, that is, the hi voltage points of the dipole look at each other thats why it works so well and thats my explanation no where else mentioned.
David, your explanations and Extra studies are awesome. Please keep the videos coming!
Thank you!
MFJ has listened and is now delivering the MFJ 8-Band Cobweb MFJ-1836+HK34 Add-On Kit. This model provides the must needed 40 meter band coverage.
Yes, I have the kit. I thought I did a video on it.
Dave,
I agree most antenna are kits. HiHI Those nuts are called nylon insert locknuts. Also referred as self-locking nuts. Loved the music while you assembled the antenna. If you plan another round of on air testing, I'll be listening near Philadelphia. 73 WB3BJU
Thanks!
Hi David, I enjoy your videos. I've got a wooden pergola over the back deck that's about 12 X 16 and I think I'll put a cobweb on top of it maybe using electric fence insulators as tie points for the wire elements. The top of the pergola is easily 20 feet off the ground and I might have room for 40 meter elements if I add just a small bit of inductance. - Jim, W4FJT
Hi Dave, I use this type antenna almost daily. Its elevated on a mast mounted to the chimney @ 32'. Its excellent at DX on 20, 17, and 15m. 12 and 10 are obviously spotty at this point considering the elevation and band conditions. My particular antenna is a Radiowavz build of the same antenna. One thing I did at the suggestion of the MFG to work NVIS is to add a slip ring radial system to work closer in stations. I have modeled it for my particular qth and works occasionally. Definitely not the best for working border states if you want to get your WAS on a wire. DX however is pretty amazing considering the narrow bandwidth, If your in FL this is a great antenna for WAS. Not so much for MO. LOL. Tuning is a must with this one. Dave is NOT kidding.
Thanks for the additional info.
Would be very stealthy if it was mounted on a resilient carbon fiber umbrella that could collapse and had a canvass/sunbrella covering. If the mast was a little tall you could put in through the hole of a patio table and work qrp in the shade.
Thanks for this, Dave. I'm convinced that the 1835H with the 40M add-on will be my new antenna for my small city lot. I plan to put it up about 40 foot and can't wait to see the results. I currently run an end-fed that works well, but is very noisy and far from ideal.
I got the MFJ-1622 (40-2M). It was about $100 shipped. My radio gear is on the 2nd floor, had the antenna set up out the window, and had the radial going down the porch roof. Following the directions for the antenna, I could only get a nice tune on 40M. I then tried having a radial cut for each specific band, tried them together, and individual. Nothing really seemed to help. Since then, I've rebuilt my home brew 9:1 with heavier wire, and put up an end-fed, grounded. The end-fed is highly superior to the MFJ antenna, covering 80-10M. I have the end-fed going from the roof near the window, to a 8ft tripod that used to be on a roof (although it could be replaced by my tree if a storm hadn't taken it down).
Thanks for your efforts... learning expensive lessons so we don't have to.
It actually looks a lot like the couple of "cobwebs" on the Tie Fighter on your shirt.
I suggest starting with the longest wire set ie lowest freq figuring it's amount of wire is going to effect the rest the most. Then only modest adjustments should be needed after tuned through to higher freqs. Then a second going through from low to high would get a good all around balance with only slight adjustments. Have fun.
After a few years in the air, How do you like this? Has it held up? I've heard the wire is terrible and wondered if stainless steel "downrigger" wire would work well.
another OG call awesome, we have an OG "old goat" as he says awesome. 73's KM4KSU
Hi David MFJ add on kit for 30m and 40m MFJ 1835HK34.
Regards Myles. from Glasgow in bonnie Scotland
Great review again Dave! But for me, I need my 40 meters! I have a ham buddy that lives in a HOA condo, and he and I are looking for a stealth antenna for him. It is a challenge for sure, but we keep looking. His HOA, BTW, was not his choice, but his wife's. 73, Karl, KO8S
Hey Dave did u see mfj came out with a 30 and 40 meter kit add on for that
Wow this looks great! I need to install an HF antenna system at some point and I suspect I could market it better as "Yeah it just needs a cover and a table underneath it!". Then again I may just do a 3 band fan dipole high enough where no one really sees it.
If you have the room to do the dipoles, I would recommend going that way. I do like the cobweb, though. Nice antenna.
Great video. Are you planning on a video for the MFJ 1796? Thinking about buying one.
Sorry, no. Not in the plan right now.
I'd like to see a frequency response sweep of each band although I haven't heard anyone on 10 or 20 meters in years so it seems pretty useless.
Thanks Dave, Have you looked at the AlphaAntenna Tuner Free HF BASE Antenna
10-80M Complete ProMaster. It is a interesting looking antenna. I have the same problem of restrictions.
Thanks for all you do
I haven't looked at it. It sure promises a lot, which makes me wonder if it can really do all that.
I may pull the trigger on it next week and see
Is it a "Folded Fan Dipole?" In respects to similarities in design?
Yes, kinda.
Would it be possible to construct this antenna in a way that it could be installed in an attic with about a 2' square opening? I would want to assemble it mostly inside and just do a final assembly in the attic. It's hot and has a lot of loose insulation, so constructing it up there would be quite frustrating. If it could be assembled in two sections, then folded out in the attic that might work.
I suppose you could give it a try. It's really designed as an outdoor antenna. Putting it in the attic could make tuning quite interesting. The only way to know is to try.
Thanks - I am currently using a 58' end-fed antenna in the attic with a 9:1 unun balun and an antenna tuner. I am within 6 states of WAS using a 5w Genesis G40 SDR transceiver using JT65 and JT9 but can't get very far out of the country. Just wondering if a better antenna might help, but I live in a restricted neighborhood.
Thank you for this video. God bless you for your help for us.
Dave are you the Wizard of antennas? Nice T-shirt
Thanks for the review David.... I am just getting ready to take the tech and geneal test and buy my first equipment and I need all the help I can get so I subscribd ! Thanks and what you suggest for my first base rig?
Any formula for calculating elements length ? Pls ...
Do you want to spend an hour deploying this at a park to operate for 20 mins? Its great for home use but it nerds to het up beyond 30 ft in height
Sounds complicated. Thanks Dave
thats cleaver well done dave, very interesting.
I don't understand what the big loop of coax loop is for. The assembly instructions don't mention it.
Ah, I see the problem. I put together the H version, which requires the balun. The regular version (lower power capability) does not have the coax loop.
I just ordered the H version, and there is no mention of a coax balun in the online instruction sheet. Maybe the sheet that is included with the antenna will mention it. Thanks for the video.
I wonder if you can do this with an OCF 40M dipole...
Hi Dave.
Thanks for the video,I do enjoy your shows, I intend to buy and use one of these antenna subject to availability in England.
I live in a restricted home and have lots of room in the garden just the job and of course I can always hang the washing on it and nobody will evere know .
How about a video about balans or maybe you have already got one ?
Thanks again for your show.
Best regards
David UK M6DFL
Balun video coming.
Hi Dave. Have you taken the time to model the Cob Web format on any of the bands? Would be interesting to see what results you came up with if you modelled it one band at a time with EZNEC. Great video as always.
I've thought of it. I'll have to turn "thought" into practice!
I love your unboxing video's! They've been a real pleasure and really
fun to watch! The cobweb antenna was interesting... (by the way I'm
still waiting for my "Civilian Bazooka" :P) How easy was it to mount to
the pole that you have it on? Could this type of Antenna be vertically
positioned as well?
The pole I have it on is a simple 8' 2x4. Then there's a short piece of steel pipe that's bolted to the 2x4, and the antenna is bolted to this. You could also bolt the antenna to a TV mast or, as I've done before, to a piece of chain link fence top rail. These are available at Home Depot for pretty cheap. Regarding vertically mounted, the only way to know is to try!
David, do you happen to know how wide the antenna is across the entire "web"? Also what type of feedline are you using?
The antenna is about 8.5 feet on a side, give or take. For the review I used RG-8X and a length of RG-213, because I was a bit short of coax.
Hi David, I live in a single story home, I have power/ telephone, and CATV lines that run above my entire backyard fence line, which is only 20 feet from the back of my home. If I can only get a few feet higher than my roof, do you think the cobweb will perform satisfactory? Do shorter verticals without ground radials perform okay?
Mine is only up about 15 feet. You can stick two chain link fence top rails together and guy it with rope with the cobweb on top. That's what I do.
I just made a. Few contacts. With the antenna
Nice review. Do you think 40 could be installed. Just to big. I have the room up about 40 ft tnxs KQ4CD
That's enough for a multiband antenna such as the HyGain AV640. Or you could just put up a 20 meter dipole.
Thanks. Very good.
Nice vid very good explaned but if you compair this with 7 BAND HF COBWEB ANTENNA 1kw on EB for less i think MFJ made a antenna that is over prices but thats my opinion on it. I dont have any cobweb but how knows i get me one this year. But i will go With the on on EB for Poland. It looks prebild not match work to get it working. Thanks David Allways like to look you vids on YT.
Each band on the cobweb needs to be separately tuned, then you should run through the tuning again as each band affects the other a little bit.
Did you try to put 800 ++ watts on it ? would love to hear it held up after all these years. I think to buy one as i got limited space to put it up legally. ( strick rules here for putting up antennas )
Be sure to get the high power version if you put that much power into it. The one I tested is the high power one and I put 500 watts into it. Sadly the antenna is no more. A deer ran into it one evening and trashed it beyond repair.
@@davecasler How did the deer get on your roof? Was it at Christmas time?
@@tomfoley1265 The antenna was mounted on a 20' pole out in the back yard. No reindeer were involved🙂
tanks for info 👍
Good vid, good info
been off the air because of hurricanes so.e time back
Nyloc nuts are very good for a project like this.
Should be spelled CobWebb because it was designed by Brit Steve Webb G3TPW.
would the hustler 5btv be good for limited space?
Yes, a used one in a very small place with all the radial tied together
like a sneak of wires going to the sides, and work fine with
600 watts.
dose a wire requier being insulated when screwed to each support tube?
The support tubes are plastic, so no insulator is needed.
At the height you have this antenna for this test would it work well for NVIS?
I suspect so, although you likely won't see much NVIS on 20m or above
What vertical antenna do you have Dave please?
Right now I have a SteppIR BigIR. It replaced the ageing Butternut HF-9V.
at 11:10 you should have played the chicken dance!
How. Tight should I tighten the leads
Just enough to hold them in place.
Interesting!... Very interesting.
so you think it`s interesting then :)
Oh, I thought everyone had 50000 acres and a good view......
We need a haircut and a shave, Dave! Good review and maybe the option I will take for my home in Phoenix. 73 KI7AQJ
Haircut yes. But my wife once saw a picture of me with no beard, and told me never to shave it off!
Hi Dave I be listing for you on 10 meter soon N8YOA
Those nuts are called nyloc nuts. They have a nylon insert to keep them tight.
Hmmm...and I thought they were simply called "pains in the ...."
A Cobwebb 10 feet off the ground will be a poor performer and is not recommended. Why not just put up a fan dipole and not bother with all this effort and get a better signal out?
The short answer is the amount of space it takes. I would not recommend putting this antenna up at less than 20 feet. A fan dipole takes 66 feet in one direction if it's for 40 m and above. Whereas the cobweb takes up far less space. It's a compromise antenna for those with not very much space. It's also a low visibility antenna. I enjoyed mine until a wayward deer took it down.
MFJ says this is good for portable use and easy to set up, any thoughts?
I measured the antenna and its 12.5 feetacross
Yes, diagonally
sorry, chicken dance at 10:52.
ladder line ??
Ladder line is an old way of making transmission line, using bare wire separated by about an inch or so, with plastic separators every few inches. It's been around since the dawn of radio, and is actually about the lowest loss transmission line available. It is commercially available, but is not cheap. The characteristic impedance is usually 600 ohms. A much more common substitute is "window line" (often mistakenly referred to as ladder line) that has a characteristic impedance of 450 ohms, also very low loss.
Tried one of these..not impressed...
I don't think that. You. Really need the extra balon
I strongly advise against purchasing this antenna. It cost me €600 and has numerous flaws. The tubes do not fit into each other properly, making assembly a nightmare. They are not machined correctly. Even after meticulously adjusting the antenna with the Nano VNA, all cables hang loose, despite following instructions. Additionally, there is no alternative since the spaces are pre-drilled in the fiberglass.
With even a slight breeze, nothing stays in place; everything moves. The wires from the 10m band overlap those from the 15m band, and nothing is properly tensioned, as you can see in this video. The tubes move in all directions, causing the SWR to fluctuate due to wind, resulting in unstable tuning as the antennas move closer together.
How is it possible to have mechanically botched an antenna in this way? I could have constructed a sturdier one myself, but I trusted a manufacturer and paid excessively for something that doesn't work. I'm not going to drill holes in the fiberglass, risking further weakening the antenna. I'll have to find a solution using clamps.
In conclusion, do not purchase this antenna.
www.kerryamateurradiogroup.com/resources/Cobwebb%20Design.pdf please follow the link this will show how the real proper one is made, I had the original one and wish I had it again ,Sorry David and mfj but is nowhere near the proper one, single wire for a start it should be at least twin wire (speaker type) Joe
There are many people who think their version of an antenna is the best. There is no "official" cobweb design. As I noted in my review, I'm impressed by the MFJ version, which is simple and works well. I've not tried other versions.
This fella got himself a cool free antenna and at the end is asking for $10 tips, smfh pops.
Yep, it is a cool antenna. MFJ just sent me gratis the extension kit for 30 and 40 meters, which will be the subject of the next video.
Lost me with the packaging