BendixKing KXP 756 - Manual (Page 39)

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decreased. The coupler is switched to
the bypass condition when a channel
change occurs. Depressing the mic
key will initiate the auto tune
sequence.
The auto coupler generates a
“READY” signal that inhibits the auto
coupler tune sequence until a channel
change occurs. The auto coupler
monitors SWR during transmit.
Should the SWR degrade to a ratio
greater than 3.6:1, the auto coupler
will start a tune cycle synchronized
with the next mic key depression.
If a PA or coupler fault is
detected, transmit is inhibited and the
frequency digits will flash indicating
the fault. Depressing the mic key or a
channel change will clear the fault
indication.
All 99 of the preset channels may
be programmed for semi duplex
simplex or receive only operation, as
desired. For the case of the semi
duplex channel, the coupler is
bypassed in receive to avoid receiver
desensitization due to narrow antenna
bandwidths.
A “receive only” channel may be
programmed to allow only receive
mode. When a receive only channel is
detected, the coupler is bypassed and
transmit is inhibited.
Frequency Mode
Operation in the frequency mode
is similar to channel mode except that
the frequency is selected as desired
rather than on a preprogrammed
basis.
Frequency selection is
accomplished by means of cursor/digit
Frequency Control knobs. No RCV
only condition applies. Only simplex
operation is allowed. Transmit is
therefore allowed on any 100Hz
frequency increase in the 2-30MHz
frequency range.
In normal operation, the
frequency, emission mode and TX
message when transmitting is
displayed. No channel number is
displayed.
When the system is transferred
from channelized operation to direct
frequency control, the initial frequency
displayed is the last frequency used
for transmit purposes when operating
in the direct frequency mode.
Previous emission mode is also saved
and displayed.
The coupler is bypassed under
the above conditions. Auto tune
sequence is initiated with the mic key.
Changing any digit on the frequency
display will cause a coupler bypass.
The cursor control is the outer
concentric knob and works in an
increment/decrement fashion. Cursor
position is annunicated by flashing the
active digit. The cursor occupies one
of six positions and moves left to right
for clockwise knob rotation.
The cursor hidden position is a
blank space between the least
significant digit and the most
significant digit. Depressing the mic
key will cause the cursor to go to the
hidden position.
The KCU 951 has the capability
of a borrow/carry type of tuning. This
type of tuning is called “rollover” and is
enabled in the aircraft wiring harness.
This allows ease in continuous tuning
up and down the frequencies (in
100Hz steps). For example, if rollover
is enabled, and two frequency digits
are 89 with the cursor on the 9, one
more clockwise rotation of the knob
will change the digits to 90. Without
rollover, the digits would revert to 80.
Normally, pilots may prefer not to have
rollover enabled, so that they may
select each frequency digit individually
without borrowing from or carrying to
the next digit.