BendixKing KHF 990 - Manual (Page 38)

SECTION III
OPERATING THE KHF 950/990
KHF 950/990 GENERAL OPERATING INFORMATION
PREFLIGHT INSPECTION
During preflight walk around inspection, it’s important to check the HF
antenna for structural integrity. Long wire antennas may be used with
the KHF 950, and these can be damaged by ice accumulation in
flight or broken by improper aircraft ground handling or fueling opera-
tions.
A ground check of the KHF 950/990 is advisable, particularly if it is
going to be the primary source of contact with Air Traffic Control dur-
ing over water flights. (It may be advisable to consider the operational
benefit of installing dual KHF 950 radios when HF communications
are the primary source of contact with Air Traffic Control. A second
unit would provide a backup and a means of monitoring other HF ser-
vices while the first radio is tuned to an ATC frequency.)
To check for proper antenna tuning, allow the KHF 950/990 to warm
up until the display becomes active (up to two minutes), select an
authorized frequency and press the microphone key. When using a
KCU 1051, “TUNE IN PROGRESS” will be displayed if the channel
had not been previously tuned. When tuning stops, the frequency
display reappears. If a fault is indicated, refer to the section
on Fault
Indication in th e pilots guide.
NOTE: When using the KCU 951 or the KFS 594, the TX annuncia-
tion should flash and the frequency display blank as the antenna cou-
pler tunes the antenna. When the tuning sequence is complete the
TX stops flashing and the frequency display reappears. If the TX fails
to stop flashing refer to the section
on Fault Indication in this pil ot’s
guide.
To check for proper operation of the system, transmit a radio check
on an authorized frequency. Make sure you can transmit and receive,
using a frequency which is suitable for the time of day.
NOTE: The warm up period is for a crystal oven to heat up which
assures an extremely high degree of frequency stability under vary-
ing environmental conditions.
Operation
3-1 KHF 950/990 Pilots Guide
Rev. 0
Dec/96