[Elecraft] David Cole...756ProIII vs K3

[Jim Brown]

On 4/13/2014 8:47 AM, Fred Smith wrote:
> I have a newer Icom here and might have to debate the receiver issue and I'm
> half deaf. The Icom does have both CW and SSB filters/D-Star in it but when
> it comes to weak signal the K3 is superior as is the KX3.

A few decades ago, Richard Heyser, one of the wise men at JPL who helped 
put us in space said about audio systems that "attempting to describe an 
audio system using only frequency response was equivalent to attempting 
to write poetry with only one word in our vocabulary."

The quality of a radio is defined by many things, some of which have 
numbers tied to them and some of which do not. Several months ago, a 
published table (was it from Radcom?) was posted here comparing the 
transmitted phase noise of a dozen or more popular rigs, including the 
K3, KX3, one or more Flex radios. A similar study could (and should) be 
published to address clicks and TX IMD, and I think Rob Sherwood has 
tackled much of that. TX and RX phase noise is a big deal in contests, 
and even in big DX pileups -- it's not unusual to hear (and see a dirty 
TX on a P3) splatter or click down onto the DX frequency! KE1B is about 
8 miles from me using an ICOM 7600 to drive a big amp. His clicks and 
phase noise wipe out about four times as much of the band as K6XX, who 
is only 3 miles away but uses K3s to drive tube amps.

FCC Rules place limits on signal purity that, if you study them and do 
the math, cannot be met by most rigs driving most solid state power amps 
to full power. A K3 driving a properly tuned tube amp does satisfy those 
Rules. Some ICOM rigs (the 7600 is one of them) allows the user to vary 
the keying rise time over a wide range, most settings are very clicky, 
including the default. I know this because I made a carefully controlled 
set of on-the-air measurements of one owned by a neighbor.

All of this is apart from ergonomics issues, about which Fred has 
written the book. :)

73, Jim K9YC