BendixKing KHF 990 - Manual (Page 90)

The MODE button is used to select transmission and reception
mode. Momentary depression of the MODE button cycles the KHF
950/990 from upper sideband (USB) to lower sideband (LSB) to AM.
The single sideband reduced carrier (A3A) mode of operation is nor-
mally disabled at time of installation. However, if it has been enabled,
this mode is annunciated with both “AM” and “USB” simultaneously
displayed.
When you store frequencies in channels for channelized operation,
you also store the mode by pressing the MODE button until the
desired mode is indicated. In preset channel operation the original
mode stored with the channel frequency is engaged whenever that
channel is first selected. The mode may be changed at any time (the
stored mode is not changed, however).
It is vital that you select the same operational mode on the KHF
950/990 that the ground station you wish to contact is using. Most all
aircraft HF SSB communications are conducted in the USB Mode.
Some ground stations continue to use the AM mode, but those sta-
tions are being phased out in favor of the more efficient SSB mode of
operation.
FREQ/CHAN BUTTON
The KCU 951 has two methods of frequency selection. First, the pilot
may direct tune (FREQ/CHAN button “out”) the system to any of
280,000 available frequencies. Direct tuning is for simplex operation
only. Using the second method, channelized operation,
(FREQ/CHAN button “in”), the pilot presets the transmit and receive
frequencies in up to 99 available channels. These frequencies are
electronically stored and are instantly available by their pilot-assigned
channel numbers. These preset channels may be used for simplex,
semi-duplex, or receive only. Frequencies may be entered in these
Operation
3-53 KHF 950/990 Pilots Guide
Rev. 0
Dec/96
FREQ KHZ CHANNEL
CLARIFIER
PULL
ON
SQUELCH
OFF
VOLUME
STO PGM
MODE FREQ CHAN
HF
ı
12345.6 99
USB
Figure 3-67 FREQ/CHAN Button