--- On Mon, 11/23/09, Hector Padron <ad4c2...@yahoo.com> wrote:
Just about time japaneese(sic) companies wake up and take the K3
architecture,its the only way to improve the receiver performance.
Well, actually it isn't. Furthermore, forgive me, but the K3 architecture isn't
really new; elderly equipment has used down-conversion to an 8 to 9 MHz first
i-f, with a second conversion to a lower i-f, where the ultimate selectivity is
achieved, for years.
The trend to up-conversion began when the ideas of general coverage receivers
incorporated into ham-band transceivers and synthesized frequency control
became popular. These are more easily achieved in the up-conversion
architecture. This is simply one engineering approach, that like most
engineering has tradeoffs, which doesn't make it bad engineering.
I believe (and I'm guessing here) that the Elecraft designers looked at the
tradeoffs and returned to an older architecture but with more modern signal
processing.
Stripped to its essence the K3 receiver is triple-conversion; a down-conversion
to 8.3 MHz, a second conversion to 15 KHz and a last conversion to audio.
Hardly anything new about this.
Elecraft has also chosen to place as much selectivity as possible as close to
the antenna as possible, which has been conventional wisdom for years.
Furthermore, it can be argued that the banks of pricy crystal filters needed to
"protect" subsequent stages in the receiver are throwback technology and not
cutting edge at all.
Before you ask, yes, I do own a K3 and it is a remarkable piece of engineering,
but for goodness sake, it's just a radio.
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