Technical information

Table Of Contents
preset channels by the pilot at any time, on the ground or in flight, to
increase the convenience of frequency selection when HF use is
required.
NOTE: The use of the concentric frequency/channel control knobs,
the PGM (Program) switch, and the STO (Store) switch are
explained in the following sections.
DIRECT TUNING A FREQUENCY
In direct tune operation, the pilot may select directly any of 280,000
frequencies in the range of 2.0 to 29.9999 MHz. The frequencies
progress in 100 Hz steps. Follow these four steps for direct tuning.
1. Access direct tune operation. Make sure the FREQ/CHAN but-
ton is “out”, in the FREQ position. Confirm this by seeing that no
channel number is annunciated in the frequency display. If the button
is “in”, a momentary press unlatches it and engages FREQ (direct
tune) operation.
2. Select the desired transmission mode: USB, LSB or AM, by
pressing the mode button.
3. Enter the frequency. Because the frequency selected may be
made up of as many as six different numbers and 280,000 frequency
combinations are possible, each digit in a frequency is selected indi-
vidually. The large concentric knob on the lower right of the control
unit may be rotated in either direction and causes one of the dis-
played frequency digits to flash. This flashing “cursor” indicates which
frequency digit will be changed by twisting the smaller concentric
knob. Twist the larger knob until the digit you wish to change flashes
and then select the desired number into view by twisting the smaller
knob. Only the flashing digit will change, and there is no need to dial
up or down to reach a new frequency-simply enter each individual
digit.
Operation
3-54
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 3-68 Direct Tuning A Frequency