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For Marconi

AudioShockwav

Extraterrestrial
Staff member
Apr 6, 2005
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Nor Cal Sierra Nevada
The Owners manual.
Astro Beam AV-150
Astro Plane
Both show the Hoop as 4 pieces of Alum that is 3/8 by 24" long.


73
Jeff
 

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  • astro_beam_av150_om.pdf
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  • astro_plane_av101_om.pdf
    2.1 MB · Views: 4

The Owners manual.
Astro Beam AV-150
Astro Plane
Both show the Hoop as 4 pieces of Alum that is 3/8 by 24" long.


73
Jeff

Yes Jeff I see that. However in modeling the hoop probably should be close to the right circumference to get the right diameter. A lot depends on how Avanti measured these pieces, but if I took such a dimension as 24" for each curved element end to end in the A/P and ignored any overlap, then I would find 4 x 24" = 96" total. I would end up with 96" / 3.1416 = 30.56" diameter.

However if these elements had a 1" - 1.5" length swagged or flattened at one end, then this overlap would affect the overall diameter and the circumference, and that diameter would be smaller than 30.56".

It is this difference in handling that I was requesting so I could make the model more correct, just in case any difference mattered.

I have three hoops from different A/P antennas. One I know is from a Top One from Coppers, that I bought new. The other two are from parts of A/P I got over the years. They are all a little different in diameters, so maybe it don't make any difference, but I wanted to check one out on a real AstroBeam, just in case.

Like I said in my PM to you Jeff, I've lost interest in this project, mainly because the results I get with my guesstimates for the mounting bracket setup on the AstroBeam is not producing a beam like pattern. I'm not sure why, unless my dimensions are wrong, but other wise the antenna is pretty simple.

Plus I don't think anybody is really interested in such an old AstroBeam as modeled, even if it might help explain how it responded with a 40 db rejection...which everybody claims these days. My original model, posted below, using a stock A/P as the driven element with the reflector/director at the proper spacing showed a bit over 25 db front to back which for me is pretty good and would be noticable in operations. I include on A/P, not to specs, with one facing one direction and the other is facing the right direction for the A/B, which shows the side view of the driven element. That little difference made a notable difference in the back end of the pattern, and a little difference in the gain simply because the top part of the radiator changed position a little bit relative to the two pasive elements.

View attachment AstroBeam not to specs..pdf

The thread on MD's has also evolved into a discussion about how well the old aluminum will hold up, and the different ideas guys used for this or that solution, process, or product to help protect against getting water in the beam.
 

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