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RE: Line Loss?



Hi Pete,

What sort of equipment do you have (or plan on) for receiving 2.4 ghz?  The 
most common way is to have a down converter, which shifts the 2.4 ghz down 
to something much lower, usually in the 2 meter or 70cm bands.  Down 
converters are designed to be mounted right at the feed point of the antenna 
(or very near by), so you are only shipping the lower frequency back to the 
shack and your receivers.  Receivers are much easier to come by for the 
lower frequency also.  Most hams convert 2.4 ghz into the 2m ham band.  I 
use an all-mode scanner (Icom  R7000) as my receiver, and a modified Drake 
2880 converter, so I picked 301 mhz for the converted signal.  It's far 
enough away from both the 2m and 70cm ham bands that I can still use either 
for the uplink without interfering with my downlink reception.

Also, a 10' dish on top of a 50' tower may be a bit hard to manage.  It's 
not likely you'd need that big of a dish; many AO-40 users got by with 18" 
(barely), and 3-4' very comfortable.  You do get a much better signal with a 
bigger dish, but you also have to aim it very carefully, which adds to the 
expense and frustration.  Plus, something that big (and heavy) on top of a 
tower is going to be hard to control in the wind.

If the trees are big, you are wise to keep the antenna as high and far from 
them as practical.  Anything green absorbs 2.4 ghz like a sponge.  (It's 
what makes a microwave oven work.)  You can't shoot through the trees - pick 
a spot where you have the lowest horizon over the trees, and use your tower.

Good luck,

Greg  KO6TH


----Original Message Follows----
From: Pete Norris <k1hzu1@yahoo.com>
To: amsat-bb@amsat.org
Subject: [amsat-bb] Line Loss?
Date: Mon, 3 Jul 2006 15:24:38 -0700 (PDT)

Hi All:
   I am very new to this phase of Amateur radio, and haven't dealt with freq 
over the 70 cm band. I am looking ahead to the European P3-Eand Eagle. I am 
considering putting up a 50' Vesto steel windmill tower, (over 100 years old 
but excellent shape-that is another story), and eventually put a 10' dish on 
it. Because of big trees etc. I will have to use approx. 200'  of feed line. 
I'm thinking about LMR-1200,with a loss of .95 db/hundred at 1 ghz. Can I 
live with the loss @2.4 ghz. or overcome it satisfactorily? Any help will be 
greatly appreciated.
   Thanks,
   Pete, K1HZU
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