[CQ-Contest] Key Clicks.... Continuing Problem

Jim Brown k9yc at audiosystemsgroup.com
Sat Nov 14 22:20:29 EST 2020

Yes, but the number of pulses per unit time doesn't describe the 
strength of the energy in each click when those clicks are the result of 
rise/fall time. When someone is clicking badly, or has excessive TX 
phase noise, it is the instantaneous amplitude, not how often the clicks 
or phase noise occur.

My measurements, which are easy to duplicate with most SDR software, 
accumulates peaks in each FFT bin for a series of dits.

Years ago, I measured my neighbor K6XX qs -49 dBC at 310 Hz from the 
carrier. He was running a K3 to a tube amp at legal limit. He and I can 
S&P within 500 Hz of the other running and perceive the other as simply 
a strong adjacent signal. Elecraft has been doing this since their K3 
was introduced in 2008, designed in 2007.

-50 dBC at 500 Hz from the carrier is FAR too wide, and -50dBC is far to 
low a signal level to measure in a contest. I'd suggest something like 
-30dBC at a much narrower spacing, because it's far easier to measure 
under contest conditions.

Another component of excessive bandwidth is transmitted phase noise -- 
that "wooshing" sound present with keydown.

73, Jim K9YC

On 11/14/2020 2:20 PM, Jukka Klemola wrote:
> Bandwidth is about a signal level at, say, plusminus 500Hz off carrier.
> Or it can be described as Hz off the carrier, plusminus, at a level, say 
> -30dBc.
> When there is one pulse per second, the side band shows a number of Hz 
> at -30dBc.
> Making two pulses creates 3dB more for that particular amount of Hz on 
> the side band while the carrier is unchanged.
> If there are 4 pulses a second, there is 6dB more for the side band 
> signal at that same separation from the carier.

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