Edward Dickinson III wrote:
>Therefore I could
>..use a little enlightenment on your comment below.
Ed,
I am talking about a very subjective situation. There are many
items that can add to a specific radios' "sound", both transmit and
receive. One area is phase shift, usually caused by an improperly
designed resistor-capacitor network in a roll-off or bandpass
configuration. What happens is that a signal at one frequency, say 500
Hz, is delayed by this circuit for a certain amount of time, and then a
signal at 1.5 khz is delayed a different amount of time. Your ear cannot
define this, but it doesn't like it.
Did you ever notice at field day, that some radios the signal just
jumps out? I do not like a perfect AGC in a radio. A perfect AGC will
keep the audio level the same, for all signal strengths. If the AGC has
a slope in it, it allows for a certain amount of dynamic range. If you
set the slope to be a 20:1 ratio, then an S9 signal will be some 4-6
times louder than an signal in the noise.Some people want a "perfect"
AGC. The K3 will let you define it.
One other area that really effects the audio sound is the distortion
that different sections of the radio add to signal. The real world
situation is that many times this distortion cannot be measured. It is
very easy to do a simple THD or IM distortion check, but then we get
into whats called TIM, or Transient Intermodulation Distortion. All
circuits from the actual product detector to the audio stages proper
effect this audio quality.
At times the chase for the perfect audio signal does become silly.
Google around and you can see articles that are written by what I call
"AudioPhools".
I have been in the radio broadcast engineering profession for some
35+ years now. Every few months we learn how simple audio is not.
But the K3 continues the Elecraft Mojo.
tom K8TB
p.s., Again, how a certain radio sounds is exceptionally subjective. The
above sentences are simply my thoughts, and are not valid where
prohibited.!!
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