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 Cobandqweb (My G3TXQ cobweb project) 
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Post Cobandqweb (My G3TXQ cobweb project)
I had had a cobwebb up at the back of my house for quite a while but due to the S9+ noise never used it, so I sold it on here at the beginning of Jan. The latest storm ssaw 100 mph winds which brought down all my aerials and wrecked them, so decided to start off from new. 1st I got my 80 meter vertical up and running and then decided to put a couple of fan dipoles up for 10 through 20 meters. They work OK, but I can only put them up in a NW -SE line which is great for South America but a good few db's down for North America and Australia. These antennas are at the front of the house and suffer none of the noise I had at the back, so I decided I would build a Moxon for ten and a cobweb following Steve's design. The moxon built out of 8mm copper pipe was a disaster as the 8 mm copper pipe wasn't strong enough to support itself, so a walk around B and Q led me to try and build a cheap but strong cobwebb using easily obtained parts from only B and Q (except for the balun) and I decided to try and build it for under £70 :this:

A walk around the garden section and I found some fairly strong plastic garden stakes 16mm x 210cm so I got 4 of those for the spreaders and a shorter 150 cm one for the box arm. I had a piece of 2 inch aluminium tubing at home so next problem was how to fix the garden stakes to the aluminium pole. Up and down the aisles I went until I arrived at the shelving aisle, there I found some nice shelf brackets and the 16mm garden stakes sat really snugly in them. 4 large ones and a smaller one for the box support pole were put in the trolley. Plumbing aisle next and a selection of suitably sized jubilee clips went into the trolley, these would be used to clamp the stakes to the shelf brackets and the shelf brackets to the aluminium tubing. Electrical aisle next, a bag of 100 tie wraps to fasten the wire elements to the stakes, and a waterproof junction box were added to the trolley. The wire elements next, but the price of wire I thought to be a bit expensive, so I left it at that for the time being.

4 off garden stakehttp://www.diy.com/nav/garden/garden-care-watering/growing/plant_supports/-specificproducttype-garden_stakes/Gardman-Garden-Stake-Green-9436535?skuId=9228403 £14.00

1 off garden stakehttp://www.diy.com/nav/garden/garden-care-watering/growing/plant_supports/-specificproducttype-garden_stakes/Gardman-Garden-Stake-Green-9426483?skuId=9717188 £1.48

3 packs off 18-25mm hose clips http://www.diy.com/nav/fix/plumbing-central-heating/pipes-plumbing-fixings/hoses___accessories/-specificproducttype-clips/PlumbSure-Hose-Clip-Pack-of-2-11478070?skuId=11988777 £3.24

2 packs off 50-70mm hose clips http://www.diy.com/nav/fix/plumbing-central-heating/pipes-plumbing-fixings/hoses___accessories/-specificproducttype-clips/PlumbSure-Hose-Clip-Pack-of-2-11478058?skuId=11988765 £2.96

3 packs off 35 - 45mm hose clips http://www.diy.com/nav/fix/plumbing-central-heating/pipes-plumbing-fixings/hoses___accessories/-specificproducttype-clips/PlumbSure-Hose-Clip-Pack-of-2-11478062?skuId=11988769 £3.84

4 off shelf brackets http://www.diy.com/nav/rooms/storage-shelving/heavy-duty-storage-shelving/flexi_shelving/-specificproducttype-brackets___fixings/B-and-Q-Utility-Bracket-White-H-300mm-9796552?skuId=10187257 £7.92

1 off shelf bracket http://www.diy.com/nav/rooms/storage-shelving/heavy-duty-storage-shelving/flexi_shelving/-specificproducttype-brackets___fixings/B-and-Q-Utility-Bracket-White-H-200mm-9796550?skuId=10187255 £1.78

1 off weather proof box http://www.diy.com/nav/fix/electrical/switches-sockets/outdoor-switches-sockets/boxes/-specificproducttype-junction_boxes/Diall-Small-Junction-Box-12608730?skuId=13129436 £2.98

cable ties http://www.diy.com/nav/fix/electrical/cable-management/cable_ties/B-and-Q-Black-140mm-Cable-Ties-Pack-of-50-12848932?skuId=13359638 £1.78

So far a total of £39 and assembly began, an update later when I've progressed further, but in the meantime a couple of photos, oh and the garden stakes are ribbed so should prevent the tie wraps from being pulled when under tension with the wire elements.
Run out of time will upload photos later.


Fri Feb 21, 2014 12:20 pm
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 Cobandqweb (My G3TXQ cobweb project) 
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Post Re: Cobandqweb (My G3TXQ cobweb project)
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_________________
Whats the effing point
160m s9+20 Noise
80m s9 Noise 15m s6 Noise
40m s8 Noise 12m s7 Noise
30m s8 Noise 10m s9 Noise
20M s4 Noise 6m s7 Noise
17m s6 Noise 2m s5 Noise


Fri Feb 21, 2014 12:34 pm
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 Cobandqweb (My G3TXQ cobweb project) 
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Post Re: Cobandqweb (My G3TXQ cobweb project)
Nice idea but have you checked the garden stakes,reason being the ones i saw in b&q had steel inserts for stability running through the centers,this may cause interaction problems when elements are attached.

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Fri Feb 21, 2014 12:58 pm
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 Cobandqweb (My G3TXQ cobweb project) 
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Post Re: Cobandqweb (My G3TXQ cobweb project)
I studied them very carefully, look like plastic, sound like plastic, so I have just been and cut one in half, you killjoy :-), good job I kept the receipts, back to the drawing board, there is indeed a steel tube, thanks, I wouldn't have cut one until I had nearly finished.

_________________
Whats the effing point
160m s9+20 Noise
80m s9 Noise 15m s6 Noise
40m s8 Noise 12m s7 Noise
30m s8 Noise 10m s9 Noise
20M s4 Noise 6m s7 Noise
17m s6 Noise 2m s5 Noise


Fri Feb 21, 2014 1:24 pm
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 Cobandqweb (My G3TXQ cobweb project) 
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Post Re: Cobandqweb (My G3TXQ cobweb project)
Recognise the garden :D


Fri Feb 21, 2014 1:28 pm
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 Cobandqweb (My G3TXQ cobweb project) 
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Post Re: Cobandqweb (My G3TXQ cobweb project)
Hmmmmm should have just had it back off you, fed up now, and I have to go and do some proper work now as well, would much prefer to go walking round B&Q :cry:


Fri Feb 21, 2014 1:37 pm
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 Cobandqweb (My G3TXQ cobweb project) 
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Post Re: Cobandqweb (My G3TXQ cobweb project)
It's still here mate. New pole, T&Ks, fixing bolts, clamps, the whole shooting match


Fri Feb 21, 2014 3:40 pm
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 Cobandqweb (My G3TXQ cobweb project) 
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Post Re: Cobandqweb (My G3TXQ cobweb project)
I too got caught out by the garden stakes when making a Moxon. I'd got a bit further on than you had done in fact to the point I was there with the antenna analyser wondering why the hell it wouldn't tune anywhere. :lol:

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Fri Feb 21, 2014 4:32 pm
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 Cobandqweb (My G3TXQ cobweb project) 
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Post Re: Cobandqweb (My G3TXQ cobweb project)
Bamboo works ok and is very cheap.


Fri Feb 21, 2014 10:30 pm
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 Cobandqweb (My G3TXQ cobweb project) 
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Post Re: Cobandqweb (My G3TXQ cobweb project)
Yes managed to pick some up this evening, and having a little play. Fiberglass will last indefinately though and I dont want to be up and down repairing the thing all the time, it has to be durable, BUT even an aluminium aerial should be serviced every 18 months or so, and it will be very cheap and quick to replace the bamboo if it will last that long. Got some bamboo and some plastic coated bamboo, and have figured out how to connect it to the shelf brackets securely without crushing it... I hope

_________________
Whats the effing point
160m s9+20 Noise
80m s9 Noise 15m s6 Noise
40m s8 Noise 12m s7 Noise
30m s8 Noise 10m s9 Noise
20M s4 Noise 6m s7 Noise
17m s6 Noise 2m s5 Noise


Fri Feb 21, 2014 11:57 pm
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 Cobandqweb (My G3TXQ cobweb project) 
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Post Re: Cobandqweb (My G3TXQ cobweb project)
Well it doesn't breathe yet but it lives. Replaced the non steel looking but steel poles for a bundle of plastic coated bamboo. Got 10 of them for £6.00 and they are 71" long, just long enough. I selected the 4 straightest and then slit a 2 meter length of 15mm hosepipe I bought for£3.00. Slid 12" lengths of the hose over the bottom of each bamboo and hose clamped them to the shelf brackets. The hose protects the bamboo from the hose clips and hopefully the extra length past the shelf brackets will give the bamboo a little extra strength at probably its weakest point. Another length was cut down to 41" and attached the same way, this is for the balun box.

A quick trip to a local electrical shop and I bought 17 meters of 2.5mm and 25 meters of 1mm plastic coated wire. That set me back £12.00 The 2.5 is for 10 and 20 meters, as it will give a little more bandwidth than the 1mm, the 1mm keeps the weight down a little.

A scrap 4" piece of 15mm copper pipe was cut down the middle and each side flattened out, these were then fastened into the balun box with 5 4mm nuts and bolts each side. Last Wednesday I ordered the 2 FT140-61 toroids unfortunately they still haven't arrived (monday today) otherwise it would have been completed and ready for tuning :cry: The 3 meters of RG316 was ordered Thursday from Westlake and arrived less than 24hrs later on Friday cost £11. This is cut trimmed and soldered ready to be wound onto the toroids.

The dipole elements (except for the 20 meter one have been fitted and the tie wraps taped to the bamboo temporarily to allow easy adjustment when tuning. I made each element side 1" longer than in Steves description, so if they require shortening I can cut each side of the dipole and slide the tie wraps in a little, that way I retain the 6" gap at the ends of the elements.

Total time spent building so far about 4 hrs and cost is about £45

Photos below are of the antenna upside dowm.

Attachment:
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I am thinking of adding some bracing to the ends of the shelf brackets, I have temporarily fastened a couple of pieces of bamboo as can be seen in the next photo, it all feels pretty solidm but a bit of extra bracing probably will not go amiss.

Attachment:
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_________________
Whats the effing point
160m s9+20 Noise
80m s9 Noise 15m s6 Noise
40m s8 Noise 12m s7 Noise
30m s8 Noise 10m s9 Noise
20M s4 Noise 6m s7 Noise
17m s6 Noise 2m s5 Noise


Mon Feb 24, 2014 5:46 pm
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 Cobandqweb (My G3TXQ cobweb project) 
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Post Re: Cobandqweb (My G3TXQ cobweb project)
Nice one , I can feel one coming on :)

Ask around fishing shops and fishing supply warehouses on the net and see if you can buy any broken telescopic poles ..

Dragon carp is a big gaff and may be worth asking ...

_________________
Voice is for CBers, amateur radio operators, the average citizen, and the military. In other words, voice is for everyone with a mouth. CW is for those who choose this newer mode of communication. Newer? Why yes. Voice has been around for a million years.


Mon Feb 24, 2014 8:17 pm
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 Cobandqweb (My G3TXQ cobweb project) 
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Post Re: Cobandqweb (My G3TXQ cobweb project)
Reminds me a bit of blue peter with a dash of scrap heap challenge, i'm sure it will work a treat once its tuned in.
Just one thing the support with the balun box looks a little too long to me.

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Mon Feb 24, 2014 8:43 pm
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 Cobandqweb (My G3TXQ cobweb project) 
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Post Re: Cobandqweb (My G3TXQ cobweb project)
g7pan wrote:
Reminds me a bit of blue peter with a dash of scrap heap challenge, i'm sure it will work a treat once its tuned in.
Just one thing the support with the balun box looks a little too long to me.

I thought that - but then I reckoned he hadn't got the 20m wires on yet ? With the usual configuration the balun box is pretty much in line with the 17m wires.

Steve G3TXQ


Mon Feb 24, 2014 10:31 pm
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 Cobandqweb (My G3TXQ cobweb project) 
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Post Re: Cobandqweb (My G3TXQ cobweb project)
Yes, the white wire is the 17 meter element. I was going to add this info later, but will do it now.

Fitting the element wires could be a daunting task, most people seem to start with 10 meters and work there way out. I decided that as the 17 meter element was a square when installed to start there and work my way in. I found the smaller elements were pretty quick and easy to position running them parallel with the 17 meter element.

It really is a pretty strong structure and very light, at a guess I would say about half the weight of an original. The bamboo spreaders aren't flimsy as I worried they might be. People get put off building things when you have to mail order, not knowing exactly what you are getting and having to wait for things, anyone should be able to decide to build this on a Sunday morning, nip down to B&Q, put it together and still have time Sunday afternoon to order the toroids.

I have a washing up liquid bottle ready to build a red light to mount above the aerial and some sticky back plastic to finish the whole thing off nicely. Splitting the hose pipe in two involved using a sharp knife, you should find a responsible adult to do this (I couldn't find one so did it myself) :D


Tue Feb 25, 2014 5:57 am
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