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Re: link budget P3E



At 08:22 PM 1/9/2006 -0800, Robert V Johnson wrote:
>Hello
>I'm getting into an area I'm not at all familiar with.  In the past I
>just would plug and try.  I need assistance in figuring out if what I
>have is capable of sucessful 'L' band operation with the next HEO.  I
>have an IC-1271A with 10 watts output on 1.2ghz., 60 feet of  50 ohm
>hardline, and a 15db gain helix.  I'm good with the downlink part from my
>AO-40 hardware.  All my 1.2ghz  equipment has been aquired after the
>failure of AO-40.  I would like to be prepared before launch.
>
>73 Bob W7LRD
>Seattle
>----

Bob,

I can relate my experience on AO-40 which may not be close to how P3E
performs on mode-L:

I ran 9.5w at a 20-dBi linear-pol antenna and got about s-2 (6-dB) over the
noise floor on the downlink.  Kind of light in competition with the mode-U
gang.  My antenna would compare at about 2-dB more gain than your
circular-pol antenna.  My guess is that 10w thru 60-foot of hardline may
not result in enough RF power with the helix (more on my website):
http://www.qsl.net/al7eb/sat.htm
http://www.qsl.net/al7eb/mw1296.htm

I now have two 20-dBi antenna (45-elem loop-yagis) fed with a combination
of 103-feet of 7/8-inch hardline and 27-foot of LMR-400 to get about 20w at
the antenna (60w in the shack).  I expect that will be more than enough and
I may get away with 5-10w at the antenna.  Photo of the dual loop-yagis
mounted inside the eme array:
http://www.qsl.net/al7eb/EME-12-01-05.jpg

But this is all guessing since no link calculations have been provided by
Amsat-DL (as far as I know).
73's,
Ed - KL7UW 
===================================
BP40iq,  Nikiski, AK      http://www.qsl.net/al7eb
Amsat #3212
Modes: V - U - L - S
===================================
----
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