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1. [VHFcontesting] PA Question (score: 1): Author: "John Santillo" <u1004467@warwick.net>; Date: Tue, 23 Oct 2012 21:39:40 -0400; Hello, I have a PA Noise Figure Question. If a power amplifier has a Noise Figure of say 7dB and a series pad of 10dB is added does the Friss Equation hold true for calculating the increased Noise Fi; /archives//html/VHFcontesting/2012-10/msg00016.html (6,989 bytes)
2. Re: [VHFcontesting] PA Question (score: 1): Author: George Sintchak <wa2vnv@optonline.net>; Date: Wed, 24 Oct 2012 00:15:07 -0400; Where is the pad added - input or output? You don't say what the gain of the amplifier is. Case 1. If you put the 10dB pad on the input of an amplifier, the Noise Figure becomes 17 dB, (10+7) and the; /archives//html/VHFcontesting/2012-10/msg00017.html (8,867 bytes)
3. Re: [VHFcontesting] PA Question (score: 1): Author: "John Santillo" <u1004467@warwick.net>; Date: Wed, 24 Oct 2012 08:16:14 -0400; George et al, let me rephrase. Let's say I have a radio with a spec'd output Noise Figure of 7dB. Now I add a 10dB pad to the output of the radio. Using the Friis equation does the Noise Figure incre; /archives//html/VHFcontesting/2012-10/msg00019.html (10,883 bytes)
4. Re: [VHFcontesting] PA Question (score: 1): Author: "Tom Holmes" <tholmes@woh.rr.com>; Date: Wed, 24 Oct 2012 10:04:04 -0400; HI John... The Friis equation extends out with a term for every stage of gain or loss in the system. So adding the pad at the end of the chain adds its noise factor, minus 1, and then divides it by a; /archives//html/VHFcontesting/2012-10/msg00021.html (13,225 bytes)
5. Re: [VHFcontesting] PA Question (score: 1): Author: George Sintchak <wa2vnv@optonline.net>; Date: Wed, 24 Oct 2012 10:39:07 -0400; John, Yes, the NF will increase but only by a very small amount, as Tom has previously shown... <<<Snip<<< If the amp is first (and having described it as a power amp, this might raise some eyebrows); /archives//html/VHFcontesting/2012-10/msg00022.html (11,766 bytes)

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