Elecraft KAT500 Owners Manual - Manual (Page 18)

15
 Antenna Selector and Indicators. Until you choose a different antenna, the KAT500 uses
antenna 1 on all bands.
1. Tap the
ANT
switch to select the desired rear panel antenna connection:
1 (ANT 1), 2
(ANT 2),
and
3 (ANT 3):
2. The antenna selection is remembered for each band, so the KAT500 will automatically
return to the chosen antenna when the KAT500 returns to that band.
3. The KAT500 switches to
ANT 1
whenever the power is off.
4. Unused antenna connections have bleeder resistors that drain off accumulated static from
rain, wind, etc.
 Tune Control, SWR and FAULT Indicators. Tap the
TUNE
switch to manually initiate a tune
operation that will search for the settings needed to produce a low SWR. To cancel a tune
operation, tap the
TUNE
switch a second time. When initiating a tune operation:
1. The indicator for the mode selected (
AUTO
or
MAN
) flashes.
2. If the KAT500 was in
BYP
mode, it will automatically switch to
MAN
mode.
3. The KAT500 opens the key line to disable the external amplifier provided the RF power
present is less than the limit specified for hot-switching (see Key Line Hot Switching
below)
4. The tune operation begins when 7 watts or more of RF is applied (see Tune Operation
below for details of what happens during tuning).
5. The
SWR
lights indicate how well the KAT500 has matched the antenna to the
transceiver. Typically an indication of 1.5 or lower is considered a good match. The
FAULT
indicator will light if an abnormal condition occurs (see Fault Conditions on page
18).
6. The KAT500 closes the key line to enable the amplifier provided the RF power is below
the limit specified for Key Line Switching (see below) and the SWR is below 2.0. If the
SWR is above 2.0 the KAT500 will hold the key line open to protect the amplifier.
Optionally you can initiate a tune operation through the rear panel
TUNE
jack with a transceiver
using the AH-4 protocol or by momentarily shorting the ring to ground. Also, a tune operation
can be initiated through the RS232 port using the KAT500 Utility Program (page 18).
Key Line Hot Switching
The Elecraft KPA500 is designed to have its key line switched to disable or enable the amplifier even
while it is producing full RF power, but many other amplifiers may be damaged doing that. To protect
those amplifiers, the KAT500 is supplied configured so that the key line will not be switched if 30 watts
or more of RF power is present. This value may be changed to match the key line switching capability of
any amplifier using the Utility Program (see page 20).