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Re: Patch Back Element -- when is the geometry incidental?




Yes, if you are truly "not to scale" then that is correct and fine.  I 
actually used a #6 screw in the center as the nuts I got were the same OD as 
the 4-40, but either will work fine.

The drawing shows the "CP" tuning screw too far away from the feedpoint if 
were to scale.

Go to http://www.ultimatecharger.com/dish.html (W0LMD)

click "dish feeds"
click "Mode L/S dual feed"

There are some to scale drawings that K5MAN has done.  You can ignore the L 
feed, and make the S reflector at least 4" in diameter.

I have a to scale "template" at my website.. but my site appears to be down 
right now.  I find making a template on the computer to scale and then 
gluing it to the sheet brass/aluminum works really well for keeping the 
dimensions correctly.  When it comes back up I'll send you the URL (or try 
http://www.fredspinner.com/W0FMS  click on "Big Dish Project" and the 
template should be on that page)

Fred W0FMS




>From: "Bill Acito W1PA" <w1pa@hotmail.com>
>To: <amsat-bb@AMSAT.Org>
>Subject: Re: [amsat-bb] Patch Back Element -- when is the geometry 
>incidental?
>Date: Mon, 23 Jun 2003 10:27:03 -0400
>
>Can a knowledgable patch person take a look at this mock up and see if
>it reflects the modifications that Fred describes?
>
>For #2 I just noted the change to a #10 screw, not the additional nut.
>
>http://webpages.charter.net/acito/FD2003/patch1.doc
>
>(Word format)
>
>Less than one week and counting.... :)
>
>
>Thanks,
>
>Bill
>w1PA
>
>
>
>----- Original Message -----
>From: "Frederick M. Spinner" <fspinner@hotmail.com>
>To: <w1pa@hotmail.com>; <amsat-bb@amsat.org>
>Sent: Friday, June 20, 2003 2:23 PM
>Subject: Re: [amsat-bb] Patch Back Element -- when is the geometry
>incidental?
>
>
> >
> > I fixed problem #1 by adding a #6 brass tuning screw on the side
>opposite on the axial line that the feed N-connector is on, 1 inch from
>the center of the shorting bar (almost to the edge) in the center of the
>patch.  Turning that screw down so its about 1/16" from the ground plane
>got the patch to resonate at the 2401 MHz,  the dip in the locus didn't
>move much.. almost not at all.
> >
> > #2 was fixed by using a brass screw for the original CP adjustment,
>and soldering a brass nut onto the CP adjustment screw.  This gave me
>the ability to actually over adjust the spread in frequency of the two
>modes.  The original #6 screw almost had to be shorted to the ground
>plane for me to see any dip in the smith chart locus at all.  My
>suggestion here is if I did it again I'd use a #10 brass screw for the
>CP adjustment screw instead.
> >
>
>----
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