Mode K Satellite Operation; Digital Mode Operation - Yaesu FT-920 Operating Manual

ence by pressing the [D
this display option to use the current offset as
a starting point for setting the VFO-A/VFO-B
relationship when tuning around the satellite
transponder downlink segment. Remember,
though, that Doppler shift will change during
an operating session, so the initial offset will
not be maintained indefinitely.
The function of the [D
to [O ], via Menu Item U-09, for this
FFSET
function to work. See page 74.
For SSB operation, be certain that each VFO
is set to the correct sideband. Initially during a
pass, it may be easier to establish the Uplink/
Downlink frequency offset on CW, then switch
both VFOs back to SSB.
N When operating on Mode K, take particular care
to check your uplink frequency before transmit-
ting, as your signal may be propagated over a long
distance on the 21 MHz band, possibly causing
harmful interference to other operators.
FT-920 Operating Manual
] key. You may use
SPLY
] key must be set
SPLY

Digital Mode Operation

The FT-920 provides outstanding capabilities for digi-
tal mode operation, such as RTTY, packet, etc.
It is important that you understand the differences
between the two keying methods provided on the FT-
920 for digital mode operation, so that the controls
and switches may be set correctly.
Most operation is accomplished using Audio
Frequency-Shifted Keying (AFSK), whereby
the Terminal Node Controller (TNC) generates
audio tones to be transmitted as data by the
FT-920. To activate this mode of operation, the
front panel Mode selection must be set to
DATA-USB (even though "USB" may not be
the actual sideband utilized in operation), and
the rear panel AFSK-FSK switch must be set
to AFSK.
The FT-920 can also accept input from a TNC
or Terminal Unit (TU) operating in the FSK ( Fre-
quency-Shifted Keying) mode, whereby a clo-
sure to ground of the FSK keying line causes
the transmitted carrier to be shifted in fre-
quency; no audio tones are produced by the
TNC or TU.
AFSK RTTY or Packet Operation
The AFSK configuration environment may be the
easiest for you to use, as the TNC then has total con-
trol of the tone frequencies, Mark/Space relationship
(normal/inverted), and other aspects of digital opera-
tion which are critical to successful operation.
Connect your TNC to the FT-920's D
the instructions on page 16. Pin 1 of the D
should be connected to the TNC's "M
"T A " line. Be sure to set the AFSK-FSK
X UDIO
switch to AFSK.
For AFSK RTTY (Baudot) or 300 bps HF Packet
operation, press the [D
and "USB" appear on the display. Now enter the
Menu system, and select Menu # U-46; set this
Menu Item for the frequency appropriate for your
operating mode:
For typical RTTY operation, select 2125-L ; this
sets the carrier injection up for an offset of
2.125 kHz in a pseudo-LSB mode, so that the
transceiver actually is operating in the "LSB"
mode (even though the display still indicates
D -USB.
ATA
jack per
ATA
jack
ATA
A " or
IC UDIO
] mode key until "D "
ATA ATA
55