Mode selection, Operation 3-63, Usb mode a3j mode – BendixKing KHF 990 User Manual
Page 100: Figure 3-76 squelch/optional selcal, Figure 3-77 mode selection
SQUELCH/OPTIONAL SELCAL
Squelch is set by rotating the larger outer concentric knob (lower left)
clockwise until background noise can be heard and then turning it
counterclockwise until background noise is eliminated or just barely
audible.
CAUTION: It is important to know that squelch operation in HF is not
as predictable as in conventional VHF communications. It is not
unusual for conditions to make it necessary to leave the
squelch knob fully clockwise to maintain satisfactory reception.
Otherwise the signal may fade below the threshold you have set on
the squelch, and you may miss an important message from a ground
station. This is unlike VHF receiver squelch where you are normally
dealing with a strong, non-fading signal. For this reason SELCAL or
ALE may be a desirable option.
MODE SELECTION
USB MODE A3J MODE
Operation
3-63
KHF 950/990 Pilots Guide
Rev. 0
Dec/96
1
S
T
O
HF
OFF
TEL
AM
USB
LSB
A3J
A3A
VOL
SQ
345.6
19
-
12
CH
M
H
Z
K
H
Z
Figure 3-76 Squelch/Optional SELCAL
1
S
T
O
HF
OFF
TEL
AM
USB
LSB
A3J
A3A
VOL
SQ
417
19 12
CH
M
H
Z
K
H
Z
1
S
T
O
HF
OFF
TEL
AM
USB
LSB
A3J
A3A
VOL
SQ
345.6
19
-
12
CH
M
H
Z
K
H
Z
Figure 3-77 Mode Selection