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[aprssig] Quad antenna construction techniques

n6lrv at cox.net n6lrv at cox.net
Tue Jan 9 15:17:06 UTC 2007


Andrew,
I have built many VHF cubical quads using some of the materials you mention here. Specifically, I've used fiberglass tubing (1") as my boom and solid fiberglass rod (1/4") as my spreaders. We carefully drilled the boom for the spreaders and simply pushed them through. They should be a snug fit and the elements will help to keep them in place. To secure the elements to the spreaders we used arrow nocks however, most modern arrow nocks are tapered inside but you can find sources on the internet for 'straight shaft' arrow nocks as well, that's what we used. My elements were made from 14, 16, or 18 gauge buss wire (tinned solid copper wire) and the driven element is fed by a piece of RG58/U coax. This coax also serves as the balun by wrapping 5 turns around the boom and taping over the turns to keep them there. Typically this piece of coax would terminate at an inline connector a few feet down the mast. The finished product works real well especially for transmitter hunting.
73,
Gary
---- Andrew Rich <vk4tec at tech-software.net> wrote: 
> Gudday
> 
> Building a quad for vhf for aprs.
> 
> I have tried metal boom (hopeless) plastic (ok) and wood (good)
> 
> I am open to suggestions on how to hold the vhf quad elements in place.
> 
> I have used dowel spreaders with notches cut into them before.
> 
> How about arrows ? they seem to have plastic bit at the end - a "bow nock"
> 
> I would like to try some more rigid wire this time, last time i used some
> failry flimsy stuff.
> 
> Got any tips for building 145 MHz quads ?
> 
> Cheers
> -----------------------------------------
> Andrew Rich
> Amateur radio callsign VK4TEC
> email: vk4tec at tech-software.net
> web: http://www.tech-software.net
> Brisbane AUSTRALIA
> 





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