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

Jim Brown k9yc at audiosystemsgroup.com
Thu Nov 12 16:50:48 EST 2020

Great post, Jim. Thanks!

Based on what I learned doing that study several years ago of ARRL Lab 
data, I completely agree. There are other things we can do as well. 
After I gave a preliminary version of that study to someone who I 
strongly suspected would pass it along to Yaesu, whose radios were the 
worst offenders, a firmware upgrade for that series of radios was 
released that improved keying to the extent that it looked more like the 
second worst offender (of that generation), ICOM. :)  If you have one of 
those rigs, by all means install the upgrade. I did before and after 
measurements of keying bandwidth on a neighbor's FTDX500. They are here.


The study of ARRL Lab data is here.


Yes, the slowest possible rise time should be used when it can be 
adjusted. The reason no adjustment is needed (or possible) with Elecraft 
rigs (beginning with the K3) is that the keying waveform is carefully 
shaped for maximum clarity and minimum clicks. Flex adopted this a year 
or so after ARRL Labs first tested the 6500 series. I don't know if 
they've tested those rigs for keying bandwidth after that upgrade.

Another major generator of clicks (and splatter) is the use of ALC 
between the transceiver and the power amp to control power. In general, 
that form of ALC should ONLY be used to protect the amp from faults in 
the antenna system, including the operator transmitting into the wrong 
antenna. :)

I haven't studied the current generation of Yaesu rigs on CW, but the 
lower cost models generate terrible splatter -- typically 2 kHz or more 
on both sides of their intended bandwidth, only 20 dB down. That is, 2 
kHz on the suppressed side of the carrier, and 4-5 kHz on the other side 
of  suppressed carrier. I discovered this when helping a neighbor figure 
out why his new Yaesu was splattering, also by observing it on other 
signals, alerting the splattering station, who told me what rig he was 

Obviously, if the transceiver is generating the splatter (or the 
clicks), the power amp will amplify it (and maybe add more of its own). 
Think about it -- if someone with one of these rigs is 30dB over S9 in 
your receiver, his sidebands will be 10 dB over S9, not great if you're 
trying to work someone on an adjacent frequency.

Yes, there were some very clicky signals this weekend. Thankfully fewer, 
as Elecraft and Flex rigs continue to proliferate.

73, Jim K9YC

On 11/12/2020 9:23 AM, Jim McCook wrote:
> Anyone who has been operating in CW contests is aware of the rampant key 
> click problem we all must deal with.
> If you are using a JA made radio, please check the CW rise time to be 
> sure it's set to 8ms (unless 6ms is maximum... which needs to be 
> changed).  Also check to be sure you're not hot switching your 
> amplifier.  Key clicks in contests have become a serious problem and 
> it's long overdue for resolution.  If you use an older JA radio without 
> that adjustment, there may be a key click mod that will eliminate those 
> clicks.
> There is a reported case of a radio set for 8ms being sent to the 
> manufacturer for repair and was returned with a 4ms setting. Please 
> check after such repair returns.
> Elecraft and Flex users need not be concerned unless something is wrong 
> with the radio.
> 73, Jim
> W6YA
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