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toughbunny
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Thanks for the suggestion, @metatron, but 1) I'd like to avoid anything illegal, and 2) that would be really expensive. I'd need two HackRF's, for $300 each, instead of two RTL dongles for $10 each. Is there really no way to demodulate the signal I'm seeing in gqrx with gnuradio or something?

I also went to ACE hardware yesterday and picked up all the stuff I need to make Andrew McNeil's drainpipe yagis, so pics coming soon, but I'll need some help connecting it with the downconverter.

Thanks!

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I was wondering if the drainpipe yagi would be aided by having tin foil wrapped around it to prevent outside interference. You know, make the pipe more of a cantenna than just structural base for the plexi yagi.

Another thing I'm contemplating is to use a 3D printer to produce the template so you can stick the elements on even easier.

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Hi,

As promised, I need help with my antenna. The downconverter I brought comes with an integrated dipole, so I unscrewed the casing and removed the dipole in order to replace it with the yagi I'm making. Here's the problem: the original dipole was attached to the downconverter with one contact point, but the directed element on the yagi is a folded dipole. McNeil shows how to attach the dipole to a length of coax, by connecting one end of the dipole with the shield of the coax and the other end with the main wire in the center. But I need to attach both ends to a single contact point (?). Does anyone know how?

Cooper, thanks for the 3d printer idea, we do have one at school, I'm just not sure if it's big enough to print the whole length, but I'll be sure to check it out. Also, would't a foil shield on the outside of the drainpipe be really fragile? Is there some sort of sturdier mesh I could use, or does it have to be solid?

Thanks, and sorry about asking so many questions at once!

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You need to attach both ends to a single point? How do you figure?

My idea with the 3d printer would involve printing the thing in sections where the section elements slide against eachother like pieces in a puzzle. You could then, for additional strength, slide a U-shape over the area where the 2 parts join. Most of the structural integrity comes from the tube itself so it doesn't have to be all that much. It just needs to stay in place.

This is something I'm planning on doing this summer when I hope to get my own 3D printer...

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For the dipole, I was figuring it might work to attach one end of the dipole to the shield of a small length of coax, and the other end to the main wire of said coax, but only solder the main wire onto the downconverter. Would that work? I tried google, and it was unhelpful, so this is really just a hunch.

Thanks!

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Sorry about that, here are pictures:

This is one where I'm pointing to the contact point with a sharpie.

post-47324-0-78521200-1428271127_thumb.p

If you need more pictures I'd be happy to email them to you, just PM me with your email. For some reason these pics have a large file size and the forum only lets me upload one. I have others that might make the problem more clear if this isn't enough.

Thanks so much!

post-47324-0-78521200-1428271127_thumb.p

Edited by toughbunny
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Looks a bit strange. The part pointed to by the sharpie, does that connect to the solder blob directly next to it, or are there additional traces on the bottom of that board aswell?

As for images, I've started using Photobucket precisely because this forum is very limited wrt space it allots users for image attachments.

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I just created a Photobucket and uploaded the pictures. Here is the link to the album: http://s722.photobucket.com/user/mikeconnors909/library/Triangulation . The password is "triangulation" (without quotes). In the first image, you see the unsoldered dipole lying next to the downconverter. The reason I'm sure that there is one contact point is that, as you see in the picture, the part of the dipole that was soldered to the downconverter (the thinner part) is just one rod, it doesn't split into two wires, so there couldn't be more than one contact point. The second picture is the one already posted on the forum. The third picture is of the dipole still soldered to the downconverter. I don't know if you can see in the picture, but the dipole was actually soldered into the solder blob next to where I was pointing with the sharpie. My bad for not pointing precisely enough.

Thanks!

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I'm thinking the metal casing itself is the other 'end' of the connection. Much like a cantenna.

Edited by Cooper
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I don't think that could be, since the dipole just goes straight through the hole to the solder glob. I just uploaded two more photos to the photobucket to illustrate this ( http://s722.photobucket.com/user/mikeconnors909/library/Triangulation ). Any other ideas? Do you think it would be possible to wire the two ends of the folded dipole to the internal wire and shield of the coax, then just wire the internal wire to the downconverter?

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Look at that image where you stare down the pole. Doesn't that look a HELL of a lot like a BNC connector to you? The 'dipole' by the looks of things even touches the inner metal section of the plug, there's some plastic isolation, the outer part of the connector complete with mounting holes.

BU-P24511.jpg

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So, would the correct approach be to solder one of the coax to the driven element as seen in the youtube video, and solder the internal wire of the other end to the solder glob on the downconverter, and the shield to the flat panel with the mounting holes as seen in the picture in the photobucket? If so, what side of the panel do I solder the shield to? Inside the rubber ring or outside?

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If you take a chunk of coax and solder the core wire to the glob of solder on the PCB and you solder the shielding of the coax to the outside of the rubber ring. I think you should be good to go.

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*side note - imgur is free, no need to register, you just have to bookmark your uploaded images URLs to keep track of them

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So I made my yagi with the copper tape and perspex, and I'm now at the part where I need to create the driven element, the folded dipole. In the video, he uses a block of wood to measure the width of the dipole, but he doesn't say how thick it is. He just calls it "your block of wood." Does anyone know how wide the dipole should be? Does it even matter?

Thanks!

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In the video for his regular yagi in a can (as opposed to your elongated yagi in a drain pipe) he simply

however in the comments to the long range yagi someone else asked this very question over a year ago to which Andrew himself replied with:
Its 5mm x2 + 2mm plastic = 12mm. when connected to the network analyzer this was the perfect size any larger than this you get increased reflection, any smaller and it does not radiate effectively.
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Given his response I think the length of wire going through the plexi is a total of 12 mm in length. Since I would suspect you get the best results by having the parasitic elements line up to the center of the driven element, the block should be 6mm on the side where you stuck the copper and (6 - plexi_width_in_mm)mm on the other side for best results.

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