[CQ-Contest] Key Clicks

[Jim Brown]

On 6/4/2020 10:43 AM, Jim McCook wrote:
> Many of those new radios have adjustable CW rise time.The manufacturer’s 
> default setting with many of them is 4ms or lower!This means this radio 
> is highly likely to be a key click generator!That setting should be at 
> least 6ms and preferable 8ms to avoid clicks.My suggestion is to use 
> Email to make friendly, non aggressive contact and explain the problem, 
> offering help to ID and test after a fix is utilized.Sometimes there is 
> a mod that can be installed to stop the clicks.People should be made 
> aware of that when necessary.

I strongly agree, Jim, and I extensively explored this issue about five 
years ago, with support from ARRL Labs.

http://k9yc.com/TXNoise.pdf
http://k9yc.com/K6XXAmpTalk.pdf
http://k9yc.com/P3_Spectrum_Measurements.pdf

And yes, variable keying rise times are a recipe for clicks. I wrote 
then that the slowest possible rise times should ALWAYS be used, and 
that ideally, the keying waveform should instead be carefully shaped to 
minimize clicks and maximize signal readability. Elecraft was the first 
to do this in their original K3. The first Flex 6000-series radios did 
not, and were pretty broad, but they subsequently issued new 
firmware/software that cleaned them up a LOT. I suspect they may be as 
clean as Elecraft, but I can't get one to measure to confirm that. Even 
at their best (slowest) settings, ICOM and Yaesu aren't even close to 
Elecraft and Flex 6000-series.

Last I looked, the bad guys in this race are Yaesu and ICOM. And 
low-to-moderate cost Yaesu radios have terrible spatter on SSB. W4TV has 
looked at this, and says that it's related to how they do AGC. The 
FTDX5000 I measured for the report above was very clean on SSB, but it 
was their flagship radio (expensive).

73, Jim K9YC