External ALC
External ALC should only be used to protect
your amplifier during operation into a failed
load, or during a prolonged overdrive condition.
ALC should not be used as a way to clip or
compress fast voice peaks, or as a primary
means of amplifier or K3S power output control.
DO NOT set the power level to maximum at
the K3S and allow the amp’s ALC to control
power output. This will result in splatter and key
clicks. Instead, adjust the drive on each band so it’s
just below the amp’s ALC activation level. (See
Per-Band Power Control at right.)
External ALC Setup
External ALC is set up using the CONFIG:EXT
ALC menu entry. EXT ALC defaults to OFF. To
turn it ON, tap 1 . 6 meter external ALC can be
turned on/off separately from HF.
The EXT ALC menu entry provides a default ALC
threshold of -4.0V, used by many amplifiers.
If you select CMP/ALC metering at the K3,
external ALC activity is indicated by 8 or more
bars. If you select SWR/RF metering, the
CMP/ALC meter icons will flash during external
ALC activity to make you aware of the condition.
Some experimentation may be required to
determine the proper setting of the amplifier’s ALC
output control, if one is provided. Start with the
control set for minimum ALC output. Then adjust
power output at the K3S such that the amplifier is
just reaching its maximum level on voice peaks (in
SSB mode) or peak CW power in CW mode.
Next, adjust the amplifier’s ALC output control
upward until ALC action just begins (or adjust the
ALC threshold of the K3S with the EXT ALC menu
entry). Finally, reduce the drive power just slightly
to provide some safety margin. The goal is to have
no amplifier ALC action during normal operation.
If you see an ALC indication at the K3S or the
amplifier, reduce the drive power.
Per-Band Power Control
If the CONFIG:PWR SET menu parameter is set
to NOR, output on all HF bands follows the present
setting of PWR . (6 m and transverter bands
are always independent of HF.) If you change PWR
SET to PER-BAND, the power level will be saved
independently on each HF band. This is especially
useful with external amplifiers, or for those who use
QRP levels on one band and QRO on another.
When per-band power control is used with an
external amplifier, you can adjust the drive ideally
on each band to prevent external ALC activation
during normal operation.
TUNE Power Level
If CONFIG:TUN PWR is set to NOR, power
output during TUNE will follow the present setting
of PWR . If you change the TUN PWR
parameter to a fixed power level, that level will be
used during TUNE, whether or not you’ve selected
per-band power control (see above).
Transmitter RF Delay
Some amplifiers have slow relays whose switching
time must be accommodated to prevent key clicks
during CW operation. If your amplifier requires
more than 8 ms of relay switching time, you can
increase the delay from key-down to RF output at
the K3S using CONFIG:TX DLY.
Use the smallest value of TX DLY that works
with your amplifier. Larger values will affect QSK
and keying timing at high code speeds.
Transmitter Inhibit
Some multi-transmitter stations require that
transmitters be able to mutually inhibit each other in
order to prevent simultaneous use of resources. The
transmit inhibit input at the K3S (TX INH) can be
set up for low- or high-active control (pg. 21).
Fan Speed
The K3S/100 includes two large, quiet fans. Fan
speeds are normally selected automatically, but you
can manually select a minimum fan speed if
desired. See the CONFIG:KPA3 menu entry.
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