Digital Modes: Amtor, Rtty & Packet; Rtty And Amtor With A Terminal Unit - Yaesu FT-990 Operating Manual

Digital Modes: AMTOR, RTIY
&
Packet
The
rT-990
offers some special features to meet
the requirements of digital modes, such as a built-
in
digitally-synthesized
AFSK
generator for RTIY
and AMTOR tntt\Smission, 1F bandwidth optimi-
zation ond automatic display offsets, and a very
fast
~Tansmit-lo-recelve
turnaround time.
RTTY and AM1'0R with a Terminal
Unit
Connect your TU to the RTTY jack on the rear
panel, as shown below. Also, set the three RTTY DIP
switches and the RTTY
TONE
slide switch in the top
aca.'SS panel for the Mark frequency, shift amount
and usual direction you wish
to
use (see page
21
for
the switch settings).
To operate, just press the R TTY mode button,
once or twiCil to select the desired sideb.1nd for
operation (which is normal will depend on your
RTTY
TO N E
slide swllch setting - if you selected
NORM,
LSB will
give normal shift:). The disploy
shows your actual Mark frequency, but if you prt.'·
fer to display the (suppressed} carrier frequency,
hold the
F AST
button while pressing Ule
RTTY
mode
button to toggle the R1TY display mode.
Flor optimum signal-to-noise ratio, usc the
2.50-
1 IZBANDIUDTH
selection for
170-Hz
shift, the 500-Hz
selection for AMTOR or 450-Hz shift, or the 2.0-
kHz selection for 850-H
:.~
shift.
OperaHo11 Digital Modes: AMTOR,RTTY
&
Packet
CAUTION
Although fhe
Ff-990
cooling system is de-
signed to handle continuous duty transmis-
sion at 100 watts output, full key-down
output for long periods is not recommended.
Especially during hot or humid
weather,
we
recommend reducing power to prest>rve the
lifc of the components. In nny case, during.
long transmissions, plnce your hand on the
left rear quarter of Ule top panel occasionally
to ensure that lt's not getting too hoL The
safest approach is to kt'llp power output at 50
watts or less during long transmissions.
Before transmitting the first time, preset the Rf
PWR control to about
12
o'clock, and set the
METER
selector to
ALC.
Key the transmitter (you can use the
MOX button) and, if necessary adjust RTIY mic gain
trimmer potentiometer VR3007 (shown on page
10)
for mid-scale ind ication.
Now you can sw itch lhe
M ETER
selector to
PO
and
$1lt the RF PWR for the desired power output.
Note that for AMTOR operAtion, you must have
the
VOX
button off C.l, and may need to use
either AGC
FAST
or
OFF
(and reduced
RF
gain)
for mode A (ARQ}.
FT-990
r
!
r----H- ~AC
~
®
Terminal Unit
FSK
ONO
RTIYIAMTOR Termi11nl Unit Intercom1ections
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