Elecraft K3 Owner's Manual - Manual (Page 37)

37
Using the Sub Receiver
The KRX3 option adds an independent, high-
performance sub receiver to the K3. It allows you
to monitor a second frequency, using different
bandwidths or modes. Diversity receive is possible
if the main and sub receivers use different antennas.
Dedicated Sub Receiver Controls
Tapping S U B turns on the sub receiver (and SUB
icon). VFO B then controls the sub’s frequency, and
also serves as the TX frequency during SPLIT.
You should leave the sub off when not in use.
This turns off the -3 dB passive splitter used when
the sub shares the main receiver’s antenna path.
Holding
S U B links the VFOs (whether the sub
receiver is on or off). The kHz decimal point of
VFO B flashes as a reminder. VFO A is the master,
moving both VFOs in tandem.
Holding
S U B for 2 seconds or longer turns on
diversity receive (pg. 38). The kHz decimal point of
VFO A flashes as a reminder. VFO A controls both
the main and sub frequencies in diversity receive,
but VFO B remains independent so it can be used as
the SPLIT transmit frequency.
SUB AF gain normally sets the sub’s volume
level. Alternatively, SUB AF can be used as a
main/sub balance control (see CONFIG:SUB
AF ). With stereo headphones or dual speakers,
you'll normally hear main on the left and sub on the
right. CONFIG:L-MIX-R selects various alternate
combinations of main/sub audio mixing.
CONFIG:SPKRS must be set to 2 if you use
stereo speakers; otherwise, set it to 1 .
SUB RF gain normally sets the sub receiver’s
RF GAIN level. If this knob is assigned to main/sub
squelch (CONFIG:SQ MAIN), then RF gain for
main/sub is controlled by the main RF gain control.
BSET: Additional Sub Receiver Settings
Normally, receive controls apply only to the main
receiver. This includes SHIFT, WIDTH,
P R E ,
A T T N , etc., as well as M O D E . To change these
settings for the sub receiver, first hold B S E T . VFO
A will show BSE T , and the S-meter will show the
sub receiver's signal level. After you’ve made the
desired sub receiver changes, tap
A /B or hold
B S E T to exit BSE T .
The sub receiver’s band cannot be set
independently unless CONFIG:VFO IND is set
to YES . If it’s set to NO , you’ll see =MA IN
when you tap
B A N D
during BSE T , and the sub
receiver band will always be set the same as
main.
Sub Receiver Antenna Selection
The sub receiver gets its RF input either from the
main receiver (sharing ANT 1-2 or RX ANT IN), or
from its auxiliary antenna input (see pg. 41).
When using
BSE T , you can tap A N T to switch the
sub between MAI N (shared) and AUX (the sub’s
AUX input). When MAI N is in effect, the 1 - 2 and
RX icons show which antenna the sub is sharing
with the main receiver. When AUX is in effect,
these icons will all be off (if CONFIG:KRX3 is set
for
ANT =BNC ) or will show the non-transmit
ATU antenna, 1 or 2 (if KRX3 is set for
ANT =ATU ).
Shortcut: If you’re not in BSE T mode, you can
quickly switch the sub between MAI N and AUX by
holding R X A N T . (Tapping R X A N T turns RX
ANT on/off for the main path.)
The sub receiver’s AUX antenna must be
well-isolated from the transmit antenna to avoid
activating the sub’s carrier-operated relay.
Using the AUX input for the sub receiver
slightly improves sensitivity of both the main and
sub receivers because the splitter is not used.
Sub Receiver Band Independence
If CONFIG:VFO IND is set to YES , you can set
the sub receiver to a different band from main.
Hold
B S E T , then tap B A N D up/down to select the
sub receiver’s band. If you only use band-
independence for the sub occasionally, you may
want to assign VFO IND to a programmable
function switch (pg. 21).
If the two receivers are sharing the main
antenna path, putting the sub receiver on a
higher-frequency band than main may result in
signal loss in the sub. This is due to sharing of the
main receiver’s low-pass filters. If you select an
incompatible band combination, the K3 briefly
displays
USE AUX as a warning. To avoid sub
receiver signal loss, use the sub’s AUX input.