# [amsat-bb] Re: Primestar L Band

Edward R. Cole al7eb at acsalaska.net
Thu Sep 28 02:39:36 PDT 2006

```At 02:25 AM 9/28/2006 +0000, w7lrd at comcast.net wrote:
>
>Hello
>How much gain can I expect to get from a 36x30 inch primestar dish.  Also
a 54X48 ps dish?  I plan to use a 5-6 turn helix feed.  I've been
googleling around and I can't find out.  I have some 7/8 hardline I'll use
from my IC-1271A running 10 watts.
>73 Bob W7LRD
>Seattle

Since the dishes are elliptical standard formula for a circular parabolic
dish will not properly calculate gain.  But if you use the smaller
dimension as a diameter in those formula you should come up with the
minimum gain.

Using 30-in, gain = 24.1 dBi at 2401 MHz
Using 48-in, gain =  29.2 dBi at 2401 MHz, gain = 23.7* dBi at 1268 MHz

* Note: The smaller dish is too small at 1268 MHz and the larger dish may
not produce this gain since it < 10 wavelength in diam.
73's,
Ed - KL7UW
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http://www.qsl.net/al7eb - BP40iq
144-EME: FT-847, mgf-1801/1402, 4xM2-xpol-20, 170w
432-EME: FT-847, mgf-1402, 1x21-ele (18.6 dBi), 60w
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```