[amsat-bb] Re: Preamp location tech question

[i8cvs]

Hi Elan, WB2IOL

Actually 50 feet of LMR400 adds 0.75 dB to the Noise Figure of your
144 MHz preamplifier and 1.35 dB to the Noise Figure of your 432 MHz
preamplifier.

Why deteriorate the Noise Figure of your receiving system adding the
losses of a coax cable between the antenna and preamplifier ?

73" de

i8CVS Domenico

----- Original Message -----
From: "Elan Portnoy" <elanportnoy at yahoo.com>
To: "'amsat bb'" <amsat-bb at amsat.org>
Sent: Friday, December 18, 2009 6:52 PM
Subject: [amsat-bb] Preamp location tech question


> Hello all,
>
> In the midst of all the excitement around the new birds, I have a question
for all of you:
>
> I have ARR preamps on both the 432 and 145 transmission lines. At the
moment, they are located in shack, just before the transceiver.
>
> Both lines to antennas are 50 feet (15.24 meters) of LMR400. How much of a
performance improvement should I expect from mast mounting the preamps? It
could be done, but I'd rather keep them inside if there's nothing to be
gained.
>
> Thanks,
> Elan - WB2IOL
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