[Elecraft] KPA-500 timing settings IC-7300

Jim Brown jim at audiosystemsgroup.com
Thu Jul 28 03:55:25 EDT 2022


On 7/27/2022 12:08 PM, Lyn Norstad wrote:
> CW Rise Time set to the default, 4ms (range 2ms - 8ms).

This is MUCH too fast, very clicky. Even the slowest is much too clicky.

See my analysis of ARRL Lab Test results done in 2014. This is all THEIR 
data, that they sent me in electronic form.

  http://k9yc.com/TXNoise.pdf

Kenwood is the cleanest of the JA transceivers, but the cleanest ones by 
a lot are Elecraft K3 and later, where they developed non-adjustable 
keying which Wayne has describes as "sigmoidal" or "raised cosine" 
shaping. He introduced it in 2007; Flex 6000 series when tested by ARRL 
(after my report) was pretty nasty, but they subsequently followed 
Elecraft's lead and got a LOT cleaner.

What we CALL CW is really 100% amplitude modulation of a carrier by a 
rectangular wave train, and the harmonics from the transition excite IMD 
that is heard as clicks. I demonstrated this in another report presented 
using Power Point, but not intented as a Power Point talk. It's simply a 
convenient way of presenting the data.

http://k9yc.com/FTDX5000_Report.pdf

Slide 13 shows the unmodulated carrier, slide 14 shows an FTDX5000 
sending dits at roughly 30 wpm.

I purposely leaked an early version of this report to someone I 
suspected would make sure that Yaesu saw it. Within days of my 
publishing it, Yaesu released the firmware update documented by later 
slides.

The only reason for giving hams adjustable rise time is MARKETING!

BTW -- there are other very slick elements of Wayne's designs that 
drastically reduce their transmitted and received phase noise, most of 
which date back to 2007 in the earliest K3.

You can see my earlier measurements of a neighbor's 7600 as he varied 
rise time. He's a GOOD neighbor; I have another with a 7600 who, for 
years, chewed up 10-20 kHz of the band on CW; K6XX and I, both running a 
K3 legal limit, 3 miles apart, can work within 500 Hz of each other and 
hear each other as simply another loud signal. These data are with the 
original K3, long before the improved synth board.

73, Jim K9YC

73, Jim K9YC

73, Jim K9YC


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