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Re: FM bird logjam



----Original Message Follows----
From: Emily Clarke <emily@clarke-design.com>
To: brobertson@mta.ca
CC: amsat-bb@amsat.org
Subject: Re: [amsat-bb] FM bird logjam
Date: Mon, 02 Jan 2006 13:21:34 -0800

There is nothing inherently different using Mode B (U/V) versus Mode J (V/U) 
however there are a few things that can account for the impression that they 
need more power.  AO-7 is nearly twice as high as other satellites (so the 
path loss is greater) but VO-52 is lower.  AO-7 in Mode B has almost twice 
as much power as VO-52, but less in Mode C (same frequencies as Mode B - 
just lower power).
{snip}

Hi Emily,

There is one other difference - the path loss on 70m is worse than on 2m, so 
there is an advantage to the satellites with 2m downlinks.  On the other 
hand, gain 70cm antennas are smaller than their 2m counterparts, and 2m 
power amps are easy to come by, so all things being equal I prefer mode J to 
mode B.

Greg  KO6TH
----
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