Cobwebb Mk2

Since having the stroke I have plenty of time on my hands recovering. So I'm going to make another Cobweb Antenna but cheat slightly with the frame as it will already be made up, this is because my coordination is not so good at the moment so I'm having ago at cheating! But if you want details my blog will supply plans for potential builders! The cobweb will be that of Steve Webb's design a G3TPW. Although a little heaver in the frame is design, I have used it with strength in mind, especially up here where I live at windy ville hill!

So watch closely now as I begin the build.......You'll need two terminal blocks each 12 spaces long, plus one Junction box about 150x 80x50mm. See how I start with interlinking the links of one the terminal blocks 2,4,6,8,and 10 with some bent wire. Links 3 ,5,7, and 9 are linked via a straight piece of wire. You need to do both terminal blocks so you end up with something like the below:

Terminal blocks are connected via some copper wire

Offer up the box to the terminal blocks

Terminal blocks now fixed in to the box by 4 screws.

Now you'll need some sort of pole to take junction box on the frame, I chose a fibreglass pole I picked up off Ebay a while back, see below.

Now I start on The Element wire, cutting out the tapped points,here's one I prepared earlier:

Notice how I marked up the measurement first and then cut out half an inch of the cover. Then I cross over the wire so it's touching each other and then solder. Complete all of the tapping for the elements like this.You should now have the junction box made together with the elements cut and tapped. so the whole completed box elements and bar should look like this:

Excuse the rug its old and very 1970s colour!
Once you're happy that the junction box has the correct contacts and all is tightened up you can make waterproof by adding some sort of silicone base paste or grease to the box,after adding the coax which has 6 winds around the box and acts as the reducer to 50 ohms you can then place the lid on the box, the junction box is now completed.

Now on to the frame, it is a fixed metal plate with 4 retractable legs made out of fibreglass tubes that slot in to each other.The legs are fixed on to the frame via bolts and it is fixed to the mast from the central position. 

Well I have taken a look at the frame and it will just not right, It's just too heavy and it sags in all the wrong places, the designer had the right idea but couldn't put it in to practise. 

So I have ordered some parts off ebay and am waiting for them to arrive which will be some more lighter fibreglass poles and an aluminium plate 200mm x 200mm. I will re-build the frame to my specifications. I don't think I'm being a pain, but I know what works and what doesn't and the original frame works!

So there you go it's that simple, even someone who has recently had a stroke can build a G3TPW cobweb ! And as a present to myself I've bought a new radio to go along with the antenna! A Kenwood TS 570D nothing special, but will make a good 2nd radio!


Well I have checked the G4TPW SWR measurements and they seem slightly out most because I'm using a larger frame, to be honest in the present state I'm in with the stroke recovery process in full swing I' not really in the mood for fixing the problem at the moment far better to wait until I feel more like doing it. |Hey ho that's the way it goes I'll store the G3TPW for the moment and work on a G3TXQ version, a slightly easier design for me at the moment.

I'm still waiting on the balun for the G3TXQ but the frame and some of the elements are looking good.
OK the Balun arrived a day later and I've sorted it in a new junction box and I've added the 10 bolts on top of the box so the junction box is now complete. So much easier than the G3TPW junction box!

The elements have been made up and are ready to be placed on the junction box.
On to the frame now;

The plate I got from ebay and is 200mmx300mm a good size that provides plenty of room with the poles. You'll notice in the end I went with wooden poles from previous versions this was set up with the eyelets from the last project I was completing. At last its beginning to resemble a cobweb antenna 

With the frame in place I wired in the elements and then did a quick check on the MFJ Meter the readings were not bad but the wooden poles looked shabby and unprofessional so I changed them for the new fibreglass ones I had just got off ebay, the antenna looked much better.

Once the antenna was set up ready on my test pole I completed the tuning. The strange thing is that when I switch from my old Cobweb and to the new one there is little difference so I did a quick check of the old antenna with the MFJ to see it was still set up correctly, it was perfect! so it must be location of the testing pole. Still, I must admit it's not a bad project to do whist recovery from the stroke!


  1. Hi Richard

    Very interested to read about your experiments with the Cobweb antenna. I have started to collect together the parts to build a G3TXO version. I am looking for a suitable push up mast to mount it on and noticed in you last photograph that you are using something similar. Could you please let me know the name/make of the mast.



  2. Hello Stephen,
    Thank you for the kind comments, I'm still playing about with cobwebs I find them fascinating! The mast is a standard fibreglass 2" pole that winds up to 20ft. My main mast is from a UK company called "Radioizing" similar to the fibreglass pole but steel, it folds in itself but the full length is 40ft. It was approximately £250 back about 3/4 years ago so I wouldn't have expected to rise too much. Best of luck with your experiments and 73s - Richard.

  3. Hi Richard
    Thanks for coming back to me. My back garden is small and overlooked so 20ft is as high as I an going to be able to raise the antenna and even then I may be pushing my luck a bit. I have considered mounting it in the loft as per your experiments but as I live in a bungalow it may not be high enough. I hope you don't mind me asking but do you have any experience with mounting the antenna closer to the ground and what would you consider a minimum height to be.

    73s Stephen

  4. Hi Stephen,
    20ft would be OK for the working height with a cobweb, any lower though, then you'd be losing out. Mind you, I've tested some cobwebs at 10ft for SWR and had no problems in transmitting and receiving so you'll be fine.
    73s - Richard

  5. Hi Richard
    I hope you don't mind me posting another question but I wish to ask about testing the balun. I built it as per various instructions found on the web and have decided to try and test it prior to installing it onto the antenna. I have placed a 10R resistor across the output and attached an antenna analyser to the input. At 14.1Mhz the SWR is 6.7 and Z 270 ohms.I had expecting to see an SWR around 1.1 and an impedance around 50 ohms. Do you know if these readings are correct and will they change once it is connected to the antenna.
    Thanks for your patience.



  6. Steve,
    I take it you gone down the build yourself route. Sounds like you have, in which case I would refer you to Steve's G3TXQ site which explains all
    I purchased my Balun as a kit of eBay which I found much easier, this was off a company called Spratreader.
    Steve Hunt does not say how he tests the Balun but I would think provided the Balun is put together correctly the testing is done with elements connected and should be 1:1 or 1:2 even at a fairly low height. I'm sorry I can't be more helpful but to be honest I didn't do a proper test, I just built it and connected the elements and then put it through the analyser when it was at about 6 ft off the ground... it worked!
    I hope this is ok?
    73s - Richard

  7. Richard
    Sorry for being a bit vague in my last post. Mine will indeed be a homemade G3TXQ Cobweb. I have just finished building the Balun as per Steve Hunt's instructions and mine does look like the one on his website. I thought I would try and test it before building the rest of the antenna, it is just the results I obtained were not what I expected.I am probably not testing it correctly. Perhaps the best thing to do is to finish the antenna and to test it again as a complete 'system'.


  8. Hi Steve,
    I would think you're right to complete the antenna first before initial testing. If then, the SWR is way out it could only be the element length or the Balun, (more likely the elements before the Balun!)Good luck and please let me know how you get on.
    73s Richard

  9. Hello Noble friend and colleague Richard

    I hope that when reading this message estajem all very well, and how is your recovery great hope my friend.
    Well let me ask you something, I pictured the new Balun and contained therein an antenna connect, I found great idea, but I wonder how it was assembled, would have some photos of this assembly, or by saying it was mounted, as I intend to use in my assembly one connect 'N' instead of RS239 shown in the picture, but I have something to base myself in this assembly and for this reason I decided to ask you this question my noble friend.
    Cordials 73's to you and your family.
    PY5KYW - Marcelo - Brazil

  10. Hello Marcello,
    I am now fully recovered thank you.
    You need to look on the bottom of the other page "cobweb antennas" to see how the Balun is built. There are pictures and a description of how its put together. If you need any more help look at Steve's G3TXQ website, it has all the details.
    Hope that helps &73s Richard

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