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Re: Circular Patch construction details

As far as drawings go:

There are drawings of the patch in .PDF format hidden on his site in the 
combination Mode-L/S
patch that were done by K5MAN.  I agree that drawings are better than 
verbose explanations...

W0LMD's S/L Page:  http://www.ultimatecharger.com/Dish_Feed_SL.html
K5MAN's Drawings:


If you are not making the dual band version, use the S-patch template but 
put a 4" (102 mm) or larger diameter reflector under the S-patch.

I have templates on my website, but the web provider was hacked, so it may 
be another day until it's back up... I'll post the URL when it's back.


As far as metric dimensions go:

In all fairness to us Americans, it's no harder for you to search the 
internet and find the conversions than it is for us.  In America its only 
marginally easier for us to find Metric screws and nuts as it is for you to 
find American sizes in Greece. (I don't know of a convienient source of 
M3.5x0.5 brass nuts, for example)...  Being that I'm in a good mood tonight, 
I decided to do it for you:

A #6-32 screw means this:  #6 size (arbitrary) with 32 threads/inch.  The 
tap hole is an American #36 drill bit, which is 0.1065 inches.  Converting 
to millimeters, this would be 2.70 mm.. the closest metric screw I could 
find is a M3x0.5 or an M3.5x0.5.

For all the screw types we use on small projects in the US here is a quick 

#4-40, #43 tap bit ==   M2.5x0.45, 2.05 mm tap bit --or-- M3x0.5, 2.50 mm 
tap bit
#6-32, #36 tap bit ==   M3x0.5, 2.50 mm tap bit --or-- M3.5x0.5, 2.90 mm tap 
#8-32, #29 tap bit ==   M4x0.5, 3.50 mm tap bit
#10-32, #21 tap bit == M5x0.5, 4.50 mm tap bit
1/4-20,  #7 tap bit ==   M6x1, 5.00 mm tap bit

Remember these are closest approximations to the American sizes.  Not 
interchangeable obviously.  Should work fine in this design, it isn't THAT 

(reference: World Wide Metric Javascript converter 
and Drill and Tap Tables, 
found both in a Google search in seconds)

So a safe bet would be to use the M3x0.5 screw for the center shorting bar, 
a M5x0.5 for the CP tuning screw and either a M3.5x0.5 or a M4x0.5 screw and 
nut for the additional frequency adjustment I suggest.  I suggest using 
brass screws and nuts for the two adjustment screws so you can solder to 

I could run the metric millimeter equivalents for you for the patch 
dimensions, but why don't you go to
http://www.worldwidemetric.com/metcal.htm for yourself and run them there.

If you still don't understand, let me know and I'll help further.

Fred W0FMS

>From: "Makis" <sv1bsx@yahoo.gr>
>To: "Amsat-BULL" <amsat-bb@AMSAT.Org>
>Subject: [amsat-bb] Circular Patch construction details
>Date: Wed, 25 Jun 2003 23:54:29 +0300
>    Hi AMSATs,
>   With a lot of interest I read all relative with the behavior of Patch.
>I had himself certain question marks for his circular behavior.
>They is pleasant that exists agreement from all for the correctness of
>Patch  and I took the decision to manufacture it.
>  But, reading the page that it describes the patch, unfortunately I find
>in his comprehension. Unfortunately they do not exist pictures, except one,
>that helping
>  whoever are not their maternal language English.
>It should you have in mind, that all Radio-amateurs there are not
>"Mechanical Engineers".
>On the other hand, for the rest world apart from America and UK, the metric
>system is
>different and it does not understand what  is the "4-40" or "6-32 tap",
>without a picture.
>  On the contrary, the patch that describes the K3TZ is 100% complete, with
>in detail drawing
>from the AUTOCAD  in both metric systems and thus I could  manufacture it
>Request: when it exists a interesting subject as this with the patch, it
>will be supposed you have
>in mind that your descriptions with the relative pages it will be supposed
>they is with more details,
>as that of K3TZ.
>    Regards
>  Mak SV1BSX
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