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On Sat, 21 Mar 2009 22:49:43 -0700, "Sal M. Onella"
wrote: In my experience, the community seems to dictate the terminology. (If you buy a big, long sandwich for lunch, is it a "hero," a "sub" or a "hoagie"?) I would call it a "grinder." More to the point, when selecting an LNA for C-band satellite, you will almost always see the noise temperature in the specs. However, for Ku-band, the LNA noise figure is usually spec'ed. I've designed for low noise, but not for amateur applications. When I did that design, I chose to work with something that appears to be alien here, NEP or Noise Equivalent Power. I did this because every circuit I know of has an input and output resistance and those were intimately associated with Johnson noise (is this too ancient a term even if many here are using his concept expressed by Nyquist's math?). To this point no one seems even remotely interested in resistance (and it would appear that the focus on a 4 or 5 degree K source of deep space would be awash in resistor noise in an amp soaking in the typical ambient of room temperature). 73's Richard Clark, KB7QHC |
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