FT-920 Operating Manual
57
AM Transmission
(Optional YF-116A AM Filter Required)
The FT-920 utilizes low-level modulation on AM, and
the DSP system may be used to enhance your trans-
mitted audio quality.
Remember that AM consists of the carrier signal plus
two sidebands. Because the available power output
is 100 Watts (total), the
carrier power should be lim-
ited to 25 Watts so as to have power available for the
modulation sidebands, which carry your voice sig-
nal.
Basic Operation
Connect your microphone to the M
IC
jack.
Set the following controls as described below:
M
ODE
: AM
M
ETER
S
ELECT
: ALC
(The ALC indicator will appear on the display)
M
IC
G
AIN
: Fully Counter-clockwise
RF P
WR
: Fully Clockwise
Press the microphone’s PTT switch. The T
RANS
-
MIT
indicator on the display will become illuminated.
Rotate the M
IC
G
AIN
control clockwise while speak-
ing into the microphone. When you reach the set-
ting of the M
IC
G
AIN
control which causes the power
output indication to increase slightly on voice
peaks, reduce the setting of the M
IC
G
AIN
control
slightly; this will be the point of best audio quality.
?
The PO meter will fluctuate significantly for an
instant at the start of a transmission; this is not
abnormal. However, if the ALC meter fluctu-
ates significantly on voice peaks, the M
IC
G
AIN
control may be set too high, and your trans-
mitted signal quality may be degraded. Reduce
the setting of the M
IC
G
AIN
control if this is ob-
served.
The DSP, VOX, and Monitor features are opera-
tional during AM transmission. See page 50 for a
description of the DSP Voice Pattern Contours,
and page 49 for details regarding VOX operation.
Monitor operation is discussed on page 50.
For low-power operation, reduce the setting of the
RF P
WR
control.
FM Operation
(Optional FM-1 Unit Required)
FM operation is permitted only in the 29 and 50 MHz
bands, due to bandwidth limitations. Be careful while
operating in the 29 MHz band to operate only in the
FM sub-band above 29.5 MHz, so as to avoid harm-
ful interference to satellite operations below 29.5 MHz.
Simplex (Non-Repeater) Operation
Connect the microphone to the M
IC
jack. Set the
M
ODE
switch to FM, and the RF P
WR
control fully
clockwise.
Close the microphone’s PTT switch to activate the
transmitter. Speak into the microphone in a nor-
mal voice level. The microphone gain level is set
automatically in the FM mode, and is not affected
by the M
IC
G
AIN
control’s setting.
Release the PTT switch to return to the receive
mode.
The VOX, and Monitor features are operational
during FM transmission. See page 49 for details
regarding VOX operation. Monitor operation is dis-
cussed on page 50.
Repeater Operation
The FT-920 may also be used, in the FM mode, for
repeater operation. Several convenient features make
FM repeater operation simple and efficient.
While operating in the FM mode on the 29 or 50
MHz bands, press the front panel [RPT] key to ac-
tivate repeater operation. Pressing the [RPT] key
causes two important functions to become activated:
r
The transmitter frequency will be shifted by a
default value (100 kHz on 29 MHz, 500 kHz
on 50 MHz) so as to access the repeater input
frequency;
r
A repeater access tone will be superimposed
on your signal, as many repeaters on these
bands use CTCSS to prevent false activation
of the repeater by random noise. Both
Subaudible (CTCSS) and Burst (1750 Hz)
tones are available.
If the above repeater shifts and/or access tone are
not appropriate for your area, they may be set inde-
pendently for each band. The Menu items which
pertain to these functions are shown below.
r
To set the 29 MHz CTCSS Tone Mode (CTCSS/
Burst), use Menu Item U-35 (see page 77).
p
Summary of Contents for FT-920
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Page 9: ...FT 920 Operating Manual 7...
