Using The Sub Receiver - ELECRAFT K3 Owner's Manual

Using the Sub Receiver

The KRX3 option adds an independent, high-
performance sub receiver to the K3. Sub receiver
installation is covered in the KRX3 manual.
You can use the sub receiver to monitor two
different frequencies or bands, using different
bandwidths or modes. Diversity receive is possible
if the main and sub receivers use different antennas.
Dedicated Sub Receiver Controls
turns the sub receiver (and
S U B
Turn the sub re ceive r off when not neede d.
This bypasses the main/sub antenna splitte r,
improving main re ceive r sensitivity by 3 dB.
VFO B con t r o l s t h e s u b ' s f r e q u e n c y , a n d i s a l s o t h e
T X frequency during SPLIT (see details at right).
Holding links the VFOs, allowing diversity
SU B
receive (details at right). VFO A is the master,
moving both VFOs in tandem. VFO B can be offset
from VFO A, or set equal to it by tapping
SUB AF g a i n s e t s t h e s u b ' s v o l u me l e v e l . Wi t h
stereo headphones or dual speakers, you'll hear the
sub on the right and main on the left. Otherwise
main and sub receiver audio are added together.
SUB RF gain n o r ma l l y s e t s t h e s u b r e c e i v e r ' s
RF GAIN level. If this knob is assigned to main/sub
squelch (CONFIG:SQ MAIN), then both main and
sub RF gain are controlled by MAIN.
BSET: Additional Sub Receiver Controls
Normally, receive controls such as SHIFT and
WIDT H, as well as the
to the main receiver (VFO A). To change sub
receiver settings (VFO B), hold
S-meter will show the sub
show , and the
BS E T
receiver's signal level. Tap
sub rece i v e r ' s a n t e n n a ( d e t a i l s a t r i g h t ) .
Some controls, including
, and cannot be set independently for the
N B NR
sub receiver unless CONFIG:VFO IND
. I f i t ' s s e t t o
Y E S NO
using these controls during
T ap or hold
A/ B B S E T
icon) on.
S UB
A
control, apply only
MO D E
. VFO A will
B S E T
to select the
AN T
, ,
B AN D P R E ATTN
is set to
, y o u ' l l s e e
when
= M AI N
.
BS E T
again to exit BS E T .
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. (Also see pg. 40.)
During
BS E T
between M AI N
input). When
icons show which antenna the sub is sharing with
the main receiver. When
icons will all be off (if CONFIG:KRX3 is set for
AN T= BNC
antenna, 1
T h e s u b r e c e i v e r ' s A U X a n t e n n a mu s t b e w e l l -
isolated from the main (transmit) antenna to avoid
activating t h e s u b r e c e i v e r ' s c a r r i e r -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
.
B
Using
B S E T
different band from main (using
CONFIG:VFO IND is set to
If the two receivers are sharing an AT U
antenna, putting the sub receiver on a higher band
than the main receiver may result in signal loss in
the sub receiver due to the shared low-pass filters.
T o a v o i d t h i s , u s e t h e s u b r e c e i v e r ' s A U X i n p u t .
SPLIT Mode with the Sub Receiver
During split (
frequency and VFO B the transmit frequency. If the
sub receiver is on, you can listen to both receive
and transmit frequencies, making DXing more
c o n v e n i e n t . Y o u c a n s e t u p t h e s u b r e c e i v e r ' s
filtering independently using
Diversity Receive
,
Diversity receive can improve signal copy during
fading (QSB). A separate antenna must be used for
t h e s u b r e c e i v e r ( A U X ; s e e a b o v e ) . Y o u ' l l a l s o
need to link VFO B to VFO A by holding
For best results, use identical crystal filters and DSP
settings on the two receivers. (Elecraft can provide
5-pole crystal filters with matched offsets on
request. 8-pole filters are already matched.)
37
, you can tap
AN T
(shared) and AUX
is in effect, the
M AI N
is in effect, these
AUX
) or will show the non-transmit AT U
(if KRX3 is set for
or 2
, you can set the sub receiver to a
B AN D
Y ES
), VFO A is the receive
S P LI T
B S E T
to switch the sub
( t h e s u b ' s A U X
- and
1 2 RX
ANT= ATU ).
) if
.
.
.
S U B