[Elecraft] K2 key clicks

[Gary Hembree]

I ran my K2/100 and one of my K2s in a QRP (5 watts) single-op 2 radio
setup during the CW sweepstakes contest this past weekend. I received two
complaints from band "neighbors" about key clicks: one on 10 meters and one
on 40 meters. Both were when I was CQing using the K2/100 turned down to 5
watts.  My main antennas are all large Yagis more than 15 meters high.
Under good propagation conditions I am loud on the east coast.

I've estimated the -60dBc keying bandwidth of all three of my K2s at around
3 kHz, independent of speed.  This measurement agrees with that of W2VGN of
International Radio 
( http://www.qth.com/inrad/ search for about-key-clicks.pdf ).  This keying
bandwidth makes it worse than that of the sample unmodified Yaesu FT1000MP
shown in the article.  W2VGN mentions that the FT1000MP gets a bad rap
simply because there are so many of them on the air.  The Ten Tec Omni VI
has also received negative comments about its CW bandwidth and it is
marginally better than the K2 in the INRAD measurements.

If you want to understand exactly how speed and keying waveform affect the
keying bandwidth of a transmitter, refer to the analysis on the following
website (the math is at the level of advanced calculus but the graphics and
narrative explain the conclusions very clearly).
http://fermi.la.asu.edu/w9cf/articles/click/index.html

73
Gary, N7IR