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Re: 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
> ----
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----
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