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Lightweight 2M yagi, aluminum TIG rods & welding?

I want to build IZ2UUF’s lightweight 2M yagi:

Any designs for such to resonate at about 146.5MHz call for elements to be 850-1000mm long (33.5-39.5"). If you live in Europe that is not an issue because all aluminium TIG rods come in 1m (39.4") lengths. However, here in North America almost all such TIG rods are only 36" long. Yes, can order an entire box of 1m rods for ~$100 but I only need 4 such rods. I have approached a number of welder’s supply outfits and smaller welding shops with the same response.

I understand that a propane torch can get these rods to melting point so am considering trying to weld a small extension piece for at least the reflector and driven element lengths, but not sure how robust such would be.

Any other ideas appreciated…

You can build a Yagi without a reflector. The reflector usually adds 4 to 5 dB of forward gain, so most Yagi antennas use one, but they work without a reflector.

Capacity hats on the ends of the reflector will make it electrically longer. A 36 inch element with hats on the ends would resonate like a longer element. Capacity hats could be pretty simple, even some wire clipped onto the end.

Or you could use two rods for the reflector and connect them together with something that is long enough.

wunder

Two US antenna manufacturers (Elk Antennas and Arrow Antennas) use arrow shafts for their VHF/UHF antennas. Amazon sells aluminum arrow shafts in different lengths. Maybe these would work for your project.

Larry,

I used 2 lengths of Al welding rod joined by by a “choc-block”.
Have a look at my blog:


to get the idea…

The welding rods that I used had a deformed section near each end, which needed to be cut off or filed down to go through the hole in the boom.

My Yagi is heavier, as it uses 2 sections of a 7 m “squid pole” & I use most of the rest of the squid pole as a 4 m high mast to support the Yagi.

Good luck,

Peter VK3PF

Simply the lightest I have seen!


@VK3YY

I copied something off the reflector here a few years back using piano wire, AKA music wire, which should be available from most hardware stores. Thinking it was Adrian, N6ZA, who sent me pic’s of what he had made. I purchased at a local Ace Hardware. I used a piece of carbon fiber for the boom. Weighs next to nothing and worked pretty well. Sourced it through Dragon Plate (dragonplate.com) ( but pricey $$) Haven’t used it for a long time now as I don’t do much VHF/UHF work unless it’s the ARRL gig. I think this was the design used: http://www.hamuniverse.com/kd5ivp2mbackpackyagi.html

Some peeps use an arrow shaft for the boom. The carbon fiber I used is really small diameter but the wires slide into it nicely for storage. Strapped to back of pack. Fun project.

73, Todd KH2TJ