Passband Tuning (Pbt) Operation - Icom ic-751a Instruction Manual

• Input both
TX
and
RX
frequencies to
VFO
and
VFO
B.
VFO A
FM
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U.
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1
U
1
VFO
B
FM
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o
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J. L
U
U.
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m
B
n
1
U
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Push the
SPLIT SWITCH.
FM
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SPT VFO A
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7-7 PASSBAND TUNING
(PBT)
OPERATION
1)
After
installing
the
UT-30
in
the
transceiver,
push the
FM
MODE
SWITCH
and program
both the transmit and
receive
frequencies
into
VFO A
and
VFO
B, respectively.
2)
Push the
SPLIT
SWITCH
to select the
split
(duplex) operation.
3) Select the transmit
mode
with either the
T/R
SWITCH
or the
PTT SWITCH.
4)
Push the
FUNCTION SWITCH
while
transmitting.
The
red
LED
lights
and
indicates
the
programmed
tone
is
being transmitted.
5)
Push the
FUNCTION SWITCH
again to cancel the tone.
NOTE:
If
no UT-30
is
installed,
the
FUNCTION INDICATOR
lights
but
no
tone
signal
is
transmitted.
Passband
Tuning
is
a
system designed
to electronically
narrow
the
bandwidth
(selectivity)
of frequencies that will pass
through
the
receive crystal
filter.
1)
The
PBT
CONTROL
has
a
detent
at
the center (12
o'clock)
position.
This position provides the widest
bandwidth, and
the
control
should normally be
left
here.
2)
The
PBT
CONTROL
may
also
be used to adjust the
tone of the
receive
audio
for
maximum
intelligibility.
3)
While
receiving
in
the
LSB mode, narrow
the
bandwidth by
turning the
PBT
CONTROL
counterclockwise to eliminate
interference
from
lower frequencies (interfering signals
are high
pitched).
Torn
the
PBT
CONTROL
clockwise to eliminate
interference
from higher frequencies (interfering signals are
low
pitched).
4)
While receiving
in
the
USB
mode, the bandwidth
is
reduced
in
the
opposite
manner.
Narrow
the
bandwidth by
turning the
PBT
CONTROL
clockwise to eliminate
interference
from
higher
frequencies (interfering signals are
high pitched).
Turn
the
PBT
CONTROL
counterclockwise
to eliminate interference
from
lower frequencies (interfering signals are
low
pitched).
NOTE: The passband tuning does not function
when
the
trans-
ceiver
is
in
the
AM
or
FM
mode.
Receiving
LSB
signal
Turn
PBT
CONTROL
cou
ntercl
ockwise
.
Receiving
LSB
signal
Turn
PBT
control
clockwise.
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