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Re: [Amps] The genius of ham radio

To: amps@contesting.com
Subject: Re: [Amps] The genius of ham radio
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Mon, 12 Jan 2015 09:58:03 -0800
List-post: <amps@contesting.com">mailto:amps@contesting.com>
On Mon,1/12/2015 8:36 AM, greg greene wrote:
  the difference between
theory and practice - is the difference between theory and practice'  what
he meant by that was that theory is the guide - practice is result, when
the two don't match - review both.  Theory is never 100% - that is why it
is theory
The word "theory" here is misapplied.  Somehow, we in the radio world, 
long before most of us became hams, divided the FCC exam into a written 
exam, which was CALLED "theory" and the CW exam. What that exam covered 
(and still does) is a combination radio Rules, operation, and 
fundamental physical principles. NOT unproven "theory."
Human understanding of how things work has been well known for a LONG 
time. Nearly 100 years ago, Bell Labs published the concept of the use 
of feedback to reduce distortion in amplifiers with a corresponding 
reduction in gain. The fundamentals of  transmission lines and antennas 
are also that old. Before that work was proven by disciplined 
experiment, it could reasonably be called "theory," even though it was 
clearly proven by the math.
- the more we observe the results of practice - the closer we get
to redefining the theory, and then the closer we get to refining the
practice.
Jim Garland addressed this quite well in his post. REAL components are 
not ideal -- inductors have series resistance and parallel capacitance. 
When we look at a circuit diagram that shows an inductor and ignore that 
fact, WE have failed to apply fundamental principles. This is not a 
failure of "theory" nor those principles. Likewise, when we look at a 
resistor and fail to see it's self inductance (and even parallel 
capacitance), and look at a capacitor failing to see it's series and 
parallel resistances and series inductance, it is WE who have failed, 
NOT "theory" -- those fundamental principles. And, of course, active 
components -- tubes, transistors, and diodes also have strays.
I was trained as an EE, and spent much of my life in the field of 
"engineering." Real engineers are trained to understand the whole 
picture, the strays, the costs of eliminating or reducing them, and when 
to stop with "good enough." We don't need, nor can we afford "ideal" -- 
we must work with the real estate that our home sits on, with the sky 
hooks that are on it, and cash in our bank account to build antennas 
that "work."
Inside our radios and amplifiers, we must look for and understand what 
Henry Ott calls "the invisible schematic hiding behind the 'ground' 
symbol," as well as the complete schematic that includes those stray Rs, 
Ls, and Cs. Failure to do that is OUR failure, not "theory," those 
fundamental principles.
Understanding HOW antennas work allows us to achieve a better result 
faster. Sure, we could build a dipole, operate it at various heights in 
increments of 5 ft, and use a drone with instruments attached take a lot 
of measured data to see it's directional pattern, both vertical and 
horizontal. Bring a very fat wallet to this process. OR, build a model 
of that antenna in NEC and have it compute the 3D pattern at various 
heights in increments of 5 ft. I've done that in a day or so. I now 
KNOW, in dB, the value of 10 ft of additional height on 80, 40, and 20M. 
That work, BTW, is on my website.
http://k9yc.com/VertOrHorizontal-Slides.pdf

73, Jim K9YC


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