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How Much Does a dB Cost?

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Subject: How Much Does a dB Cost?
From: (Pete Smith)
Date: Mon, 22 Jul 1996 11:25:31 -0700
>Back when I was a pup, I was very much impressed by W3AFM's QST series on
>station design.  One aspect that struck me as particularly interesting was
>his use of the marginal cost of a dB as a means of deciding where to invest
>next in his station.
>Rereading the series 30+ years later, some of the specific numbers he came
>up with seem questionable, but the basic concept is certainly sensible, and
>maybe worth an updated article on the subject.  Rather than put my ideas
>down and then (if I got up the courage) circulate them to the reflector, I
>thought I would invite you all to give me your thoughts first (direct e-mail
>please, for the sake of reflector bandwidth).  Any finished article will
>give credit to contributors, while (as usual) reserving any blame for
>mistakes to the author.  At a minimum, I promise to summarize and make the
>summary available.
>Here are some of the questions that occur to me.  Feel free to answer these,
>and to add your own pet issues.  I am well aware that there are many, many
>variables, and that there will be no single answer -- but at least I hope to
>suggest a way of thinking about the subject that each reader can apply to
>his/her particular situation, interests, etc.  Questions:
>1.  How does the value of a dB of station performance vary between
>contesting and DXing?  It has been said that for contesters a dB means an
>entire layer of stations previously unworkable now becomes workable.  Is
>that true?  Is there a corresponding figure of merit for DXing?  How can it
>be measured?
>2.  How should a station designer "weight" changes that affect both
>receiving and transmitting performance (e.g. tower height, antenna gain)
>compared with those that only affect one or the other?  For example, some
>receiving improvements are really cheap (per dB), but may run into overall
>system limitations (atmospheric noise,etc.).
>3.  How should I treat the question of balancing transmitting and receiving
>performance?  How do you tell if you're an alligator, or the opposite?
>3.  What are appropriate rules of thumb for calculating the marginal cost of
>a dB of amplifier?  Tower?  Antenna gain?
>4.  How should I deal with station changes that don't affect the strength of 
>signals (either transmitted or received), but that arguably improve the
>station's ability to achieve its goals (e.g. packet for DXing, computer
>contest logging software with new capabilities such as band-mapping or super
>check partial)?
>73, Pete Smith N4ZR (ex W8QZR, HL9TM, K4FOK, 3B8DT)
73, Pete Smith N4ZR (ex W8QZR, HL9TM, K4FOK, 3B8DT) 

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