User guide

In direct tune operation, the pilot may select directly any of 280,000 fre-
quencies in the range of 2.0 to 29.999 or 29.9999 MHz. Installation con-
figuration may limit the upper frequency to 22.999 or 22.9999 MHz.
There are two types of frequency operation. “Simplex” is tuning the
same frequency for receive and transmit. “Semi-duplex” (sometimes
called “split”) is tuning two different frequencies, one for receive and one
for transmit. It is important to know the requirements of the desired
ground station when tuning these frequen-
cies. Virtually all aviation services operate
on simplex.
SIMPLEX DIRECT TUNING
1. Turn the left outer knob to FREQ. See
Figure 5. The frequency shown in the
upper row of the display is the receive fre-
quency indicated by the RX on right of the
display.
2. Select the desired frequency using the
right inner and outer concentric knobs.
The outer knob changes the frequency in
.1 MHz increments. The inner knob changes the frequency in .001 MHz
(1 KHz) increments or .0001 MHz (100 Hz) increments, depending on
the configuration selected when the system was installed.
Revision 1 May/2003 KHF 1050/PS440 Pilot’s Guide
5
Figure 5
Frequency Band (MHz) Daytime Distance (Miles) Nighttime Distance (Miles)
2.8 & 3.0 Up to 100; Often unusable Up to 400
3.4 Up to 150; Often unsable Up to 800
4.4 Up to 200 Up to 1000
5.5 Up to 300 100 to 1200
6.5 100 to 600 200 to 1500
8.8 200 to 800 400 to 1500 or greater
10.0 300 to 1000 500 to 1800 or greater*
11.1 400 to 1200 600 to 1800 or greater*
13.3 600 to 1500 or greater Often unusable
17.9 700 to 1800 or greater* Often unusable
21.9 900 to 1800 or greater* Often unusable
The transition between daytime and nighttime distances may occur gradually
over a several hour period. During this transition, communication distances
between the daytime and nighttime distances listed will generally be realized.
* At times,communication may not be possible on this band during this time-
frame. However, during periods of good propagation, worldwide communica-
tions may be realized.
Table 1 - Typical HF Signal Propagation Distance for Common
Aviation Bands
KHF1050 PG R1 4/29/03 3:14 PM Page 5