Hi all,
I want to make sure there's no confusion on the list about how the K2's
transmit ALC operates in CW mode.
"ALC" means "automatic level control." It maintains a relatively
constant power output level. In the K2, we apply ALC sparingly in CW
mode so we don't cause any distortion of the keying envelope. Some
transceivers apply ALC very aggressively, so that at some power levels,
the CW keying envelope can end up with a much faster or slower rise or
fall time, which in turn can cause the keying to be too hard or soft.
ALC is activated to stabilize power output level when any of the
following occurs:
- on first power-up
- whenever there's a band change
- when you rotate the POWER control
- whenever you activate TUNE or TUNE+DISPLAY
- when reflected power increases dramatically,
which can occur if the antenna is accidentally disconnected
In high-power mode (KPA100), ALC is also running continuously, making
very small adjustments at a rate of about one per second. This is
because the gain of the 100-W PA devices changes slightly as the
devices warm up. Without this correction, power would rise 20% or more
during TUNE.
Someone posted recently about power being too high at one end of 80
meters (10 W) after having set it lower at the high end of 80 meters (5
W). This could occur because of a variation in flatness of the 80-m
band-pass filter, a variation in antenna impedance, or both. Since ALC
is not activated simply by changing the VFO frequency, the operator in
this case should simply touch the POWER control, manually activating
ALC for a brief period. Power will then stabilize over the course of
the next few CW characters.
73,
Wayne
N6KR
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