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" <[email protected]> To: "'amsat bb'" <[email protected]> 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 > _______________________________________________ > Sent via [email protected]. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
