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*Subject*: Re: [amsat-bb] AO-40 spreadsheet*From*: Douglas Braun & Nadia Papakonstantinou <doug@xxxxxxxxxxxxx>*Date*: Mon, 28 May 2001 21:52:14 -0400*In-Reply-To*: <200105281448.f4SEmsW11901@ptialaska.net>

I pulled out my copy of the Manual to correct the formula, but I got really confused after reading it. The way it is laid out and parenthesized, I cannot really figure out how to properly evaluate it. (I think there is a good reason why they stopped using "x" for multiplication after 9th grade...). Also, the way I interpreted Ed's correction, it looks like the result would be undefined if L3 was 1, since you would be dividing by zero. Finally, I just noticed that T3 does not appear anywhere. If I needed to actually do the calculation, I would feel a lot more confident grabbing it from a known-good spreadsheet. Doug Na1DB At 10:48 AM 5/28/01 , you wrote: >Domenico also refers you to Bob Atkin's, KA1GT, article "Noise Temperature, >Antenna Temperature and Sun Noise" published in The ARRL UHF/MICROWAVE >EXPERIMENTER'S MANUAL. Bob's articles are good reading on the subject, >however there is an error in Bob's noise figure formula on page 7-57. It >will give you fits if you are using it to evaluate your system. This >article was originally published in QST in the 1980's and the error has >escaped correction and been copied often. The problem lies in the third >coax cable loss expression T(L3-1). It should be: T*L1*L2/G1*G2*(L3-1). > >I have a noise figure/MDS Excel spreadsheet [cascade.xls] that computes >system noise temp/NF for you: http://www.setileague.org/software/spreadsh.htm ---- Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA. To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org

**References**:**Re: AO-40 spreadsheet***From:*Edward R. Cole

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