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Re: Small Dish and Helix w/cup



Hi Jerry,

Thanks for the pictures, and the great results!  This is very
encouraging.  Can you publish (or re-publish if I missed it)
the dimensions of the helix-in-a-can feed?  I'd like to try this
as well.

Greg  KO6TH

p.s.  better put some guy lines to the bottom of the grill before
the next overhead pass, or you'll have the whole thing fold up on
you...


>From: K5OE@aol.com
>To: amsat-bb@AMSAT.Org
>Subject: [amsat-bb] Small Dish and Helix w/cup
>Date: Mon, 28 May 2001 19:19:03 EDT
>
>Okay, it's Mark Hammond's fault, who asked me how I attached the helix feed
>(earlier email).  I had not attached it--only held it out in front of the
>dish :-)  Surely I had something around here I could scrounge up to support
>this thing?  Luckily, I had some 1-1/4" steel angle left over from my
>4x28-turn helix project and used a piece of it to attach the helix w/cup 
>and
>Drake, put it up on the rotator, just in time to listen to UO-11 on a 10
>degree pass.  I heard it about 6-9 dB above the noise (wav file available 
>on
>request).  What is important, however, is I have never heard UO-11 below
>15-20 degrees before with a helix!  This is a very temporary installation
>(see the pix below), so I guess I will be up at 1:30 AM when AO-40 comes 
>over.
>
>If you are wondering why I started down this path, it was because I thought
>if I could reduce the typical helix reflector diameter, you would gain more
>use of the dish--not blocked by the big reflector.  With a small dish like
>this, that is even more important.  This cup design is only 66 % of a 1.0
>lambda reflector and a mere 44 % of the typical 6" reflector.  The final
>spacing was 12" to the back of the coffee can.  Mark is right:  this is 
>fun!
>
>Here are the pix:
>http://members.aol.com/k5oe/helix_cup01.jpg
>http://members.aol.com/k5oe/helix_cup02.jpg
>http://members.aol.com/k5oe/helix_cup03.jpg
>http://members.aol.com/k5oe/helix_cup04.jpg
>73,
>Jerry, K5OE
>----
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