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R: QFH modification



Hi Robin

To bend the annealed copper tubing without to squash the pipe in the
bending points it is necessary to fill in it and press in it fine sand.
Remember how to load a gun in early 1700 ? Do the same using sand after
that close the pipe squeezing both end in a wise.
Remember do not anneal the pipe at this point when the ends are closed
because the sand contains umidity ! !
After bending the pipe in all points that you need the closed ends of the
tube are cut away with a saw and the sand will be removed from the inside
with easy.

Best 73" de

i8CVS Domenico


----- Original Message -----
From: Robin Callender <robin_callender@hotmail.com>
To: <amsat-bb@amsat.org>
Sent: Friday, March 18, 2005 4:47 AM
Subject: Re: [amsat-bb] QFH modification


> On the subtopic of antenna material and copper tubing ---
>
> Has anyone tried the tubing available at Small Parts Inc.?
> This is the source I had lined up for some future L- and S-band QFH
antenna
> building dreamworks.
> http://www.smallparts.com/products/descriptions/ttrc.cfm  and
> http://www.smallparts.com/products/descriptions/htc.cfm
>
> I have not tried this particular copper tubing but it looks like available
> in small diameters sizes (1/16" (1.59mm) to 1.5" (38.1mm)) and reasonable
> lengths (36inches). Is there any reason to believe this tubing is not
> suitable?
>
> What I haven't found is a good affordable tube bender for these small
> diameters.
>
> Robin
>
>
> ----- Original Message -----
> From: "Oscar Diez" <hbottiki@gmx.de>
> To: <amsat-bb@AMSAT.Org>
> Sent: Thursday, March 17, 2005 12:53 PM
> Subject: Re: [amsat-bb] QFH modification
>
>
> > Dear Mak,
> >
> > you are talking about the "thin" diameter UT-141 hard line ?
> > (BTW, that one is easily available by mail order here in Germany)
> >
> > Then certainly you mean the construction of a UHF QFH model, right ?
> >
> > In the case of the UHF antenna it will be very difficult to find
> > such a thin hollow copper tube (most easily available hollow tubes
> > from DIY stores start at about 6-8mm outer diameter and thats too
> > large for the UHF QFH model, since the outer diameter of the
> > conductor is one important construction detail of this antenna type)
> >
> > For VHF this method should be OK (as Dave suggested) and is widely used
> > in the 137 MHz NOAA satellite QFH variants you can find on internet
since
> > the required outer diameters of the four loop elements are much thicker.
> >
> > Please wait until I have my website ready. I just finished to build my
> > new QFH yesterday (based on the design of Art, with Bazooka balun, AKA
> > sleeve balun). Now I need to make the whole QFH weatherproof and I need
> > to build a new preamp for it and mount it on the roof. It will certinaly
> > take some more weeks for getting the first impressions "on air".
> >
> > 73 de Oscar, dj0my
> > ----
> > Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> > Not an AMSAT member? Join now to support the amateur satellite program!
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> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> Not an AMSAT member? Join now to support the amateur satellite program!
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----
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