avanti sigma 2 hoop length x diameter ???

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prettypolly
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avanti sigma 2 hoop length x diameter ???

Post by prettypolly »

Hi does any body know the size length circumference of the avanti sigma 2 hoop please thank you .
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prettypolly
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Re: avanti sigma 2 hoop length x diameter ???

Post by prettypolly »

or the impedance circle for you techys
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Re: avanti sigma 2 hoop length x diameter ???

Post by prettypolly »

anybody ???
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NUBSTER
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Re: avanti sigma 2 hoop length x diameter ???

Post by NUBSTER »

TBH a Sigma 2 has'nt got a hoop as far as I can remember, well the ones from 70's didn't , the Avanti Sigma 4 did though, give me a couple days I will if I have some info on the Sigma 4 ,but I'm sure the Sigma 2 has no hoop on it did'nt take me long I found this on a Sigma 4 well the copy of one it is, also found this on the Sigma 2 just realised they do have a small ring at the bottom {bnghd}
link owners manual/instrutions http://www.cbtricks.com/ant_manuals/ava ... 170_om.pdf
I hope any of this helps :thumbup:
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Re: avanti sigma 2 hoop length x diameter ???

Post by cubwolf »

Theres a link to the Sigma 2 in my one drive here https://onedrive.live.com/redir?resid=D ... file%2cpdf
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prettypolly
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Re: avanti sigma 2 hoop length x diameter ???

Post by prettypolly »

thanks but still no measurements
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Phoenix
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Re: avanti sigma 2 hoop length x diameter ???

Post by Phoenix »

Should be really easy to make with stiff wire as a template then make it out of copper brake piping...You dont say if you have an AV170 though...The ring worked as an impedance matcher for the coax but all the magic was done inside the fiberglass insulator..If you are making one from scrach you will be struggling to copy it exact but you could use these methods.

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Hope this helps
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Re: avanti sigma 2 hoop length x diameter ???

Post by wa10 »

I posted the measurements on wwdx years ago but there are so many posts i can't find it, may have been lost when they changed servers, i can measure it again if you are in no rush as i don't have the antenna here,

If you are trying to copy that matching setup there are 2 versions, the original avanti is open circuit, the later antenna specialist version was modified with a dc grounding coil and a slightly shorter radiator like my avanti saturn which uses the same loop and vertical as the sigma2,
Both have a parallel capacitor of 40 some picofarad formed by the 2 aluminium slugs inside the fiberglass that the loop bolts to,

my mate copied my hoop without the capacitor and could not get a good match with his homebrew 5/8 so he changed it to the shunt fed ringo style matching that Phoenix posted above.
W8JI
"An antenna with a poor ground using few radials cannot have a support mast grounded to the radial common point (at least it shouldn't if designed properly) There is no exception to this!
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prettypolly
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Re: avanti sigma 2 hoop length x diameter ???

Post by prettypolly »

its either 3 foot long then make a hoop or its 6 foot long then make a hoop .. i have the remenents of one here so id like to get it going again
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