Hi-Gain Vertical Half Wave Antenna

[Maximus]

Lee, you are the man! Please upload the instructions.


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[Maximus]

I have the original build instructions, plate measurements, coil winding lengths etc for all 3 versions, 50, 250 and 350watt versions. The main failure was the cheap plastic insulation pipe, if you used Teflon pipe instead a 50 version will withstand 150w no probs.

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[hereclit]

Lee , where are you man? Please , upload schematics, if you want to help us.

[MiXiN]

Lee , where are you man? Please , upload schematics, if you want to help us.

He's not been on here since yesterday afternoon mate.

It might be best that people PM him, then that way he should receive eMail notifications as he's not a regular here.

[Maximus]

Just realised, I think he's from the well known station in the Leeds area. They've always gotten out well, explains why


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[pirateaddict]

Yep he is connected to that Leeds station.. Apparently they were moving premises a month ago as they were Internet only..Maybe planning a return to fm coz i don't think anyone listened to em on the Internet.. Their Facebook hasn't been updated since early November neither.

[Frequent Lee]

Cheers guys for identifying me. You had a gift horse, but you've just bitten the hand that would have fed you. I'll upload some photos of a couple I've built recently for other stations, and if your lucky I may give the build PDFs for Xmas.

[Frequent Lee]

https://www.dropbox.com/sh/bv59wrf765xb ... 8fFRa?dl=0

[Frequent Lee]

Happy Christmas. Yea I'm the dickhead according to many on here, but I've just given you all the equivalent of a unicorn. Enjoy.

[Albert H]

Nice one Lee. A real Christmas present for anyone who wants a serious aerial!

A word of warning to everyone here - you're all going to build the 150W version, because that's the most common rig rating these days. Remember to switch the rig off before tweaking anything!!!

The RF voltages developed in the matching circuit are gigantic and can kill. If they don't "dead" you, they'll certainly burn you!

[pirateaddict]

Yo frequent Lee chill man..No one is avin a go mate as far as I can tell..Is the wireless coming back on then? Missing it!

[nrgkits.nz]

Thanks Lee, i'm going to try building the high power one when I have some time.

I did build the 50w version some years back going on info obtained from the old radionecks. With just 4w going through it I had tiny sparks flying when running a screwdriver across the capacitive plate, the screwdriver had an insulated handle of course, so heed Albert's warning!

[MiXiN]

I want one, so can't wait to see a few on eBay soon! Lol

[shuffy]

Lee, thanks for the plans. I've been messing around with similar designs to this for a while. Couple of quick questions, the lengths of the plates are pretty clear in the plans but I've probably missed what the widths are. Could you either let us know or tell me I'm a numpty and I'll read it again. Also what are you making your plates and strap out of, I assumed it was sheet aluminium but can't really tell from the pics. The rest I can guess. Cheers - top man!

[hereclit]

Thanks LEE for documents. Has anyone a list with all materials who need for this antenna ?

thanks

[nrgkits.nz]

Your local hardware store should have some good materials, the last one I made I used some plastic conduit for the base and part of an old TV antenna for the radiator

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[Maximus]

Thanks for the docs Lee
I think I had them a while ago and was too selfish to upload them on here. Hanging my head in shame


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[yellowbeard]

I am not familiar with this antenna so I have a couple of questions - first is this what it is electrically:



And second does it need the traditional choke balun of 5 or 6 turns of coax under the antenna.

[Maximus]

Yes Yellowbeard. Your diagram is correct

The additional balun isn't required.

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[Albert H]

A choke value can help to reduce radiation from the coax outer, but if you've got the match right, that should be pretty minimal.

One essential thing to remember is to tune the aerial in "free space": it must be at least 10m away from any structure. I've tuned them in my back garden, but had to use a 10m pole to support it to get it well clear of fences and walls. Raising and lowering the pole to tweak the match was a PITA but it meant that when it went "up the block" on a big pole, the match was perfect.

This aerial is closest to the ideal vertical VHF radiator for broadcasting. It has a truly omnidirectional pattern that's like a flattened doughnut. It even works well from fairly low sites. Remember to install it in free space - on the longest pole that you can. They're tricky to match accurately, but they're superb when working!