K - Kilo - dah-di-dah
K.
1. The Morse Code
abbreviation for "any station respond" or "over".
2. The multiplier shorthand for 1000 (or 1024 in binary).
See: Kilo
Key Clicks.
In morse (on off carrier keying), if the carrier wave is turned on or off rapidly, the bandwidth will be very large; if the carrier turns on and off more slowly the bandwidth will be smaller. The problem of excessive bandwidth used by a morse transmitter which turns on/off too sharply is known as key clicks. If a perfectly made morse (CW) transmitter's output is fed into a series of cascaded class C stages, then the output will likely suffer from key clicks, since the output power of a class C stage increases greatly when input power is increased slightly.
Kilo.
The metric prefix for 103, or times 1000.
Kilohertz (kHz).
A unit of frequency measurement equal to 1,000 cycles per second or Hertz.