Curtis Computer kb4900 - Baudot Keyboard Operation

Move the "TUNE/DP/SELF—TEST"
switch
to “UP”
and the transmitter
will
key
in the
CM mode.
Vou
may
tune
the
transmitter either
by
typing
CTRL-9
or
by
placing
the
"TUNE/OP/SELF-TEST"
switch in
"TUNE".
CTRL-9
will
give
you
a
string
o4
dots to avoid
overheating
the
transmitter
final
stage
during
protracted
tuning.
The
"TUNE" switch holds
down
both
the
keyline
and
the PTT line.
By
sending
either
from
the
keyboard
or the
paddle,
both
the
keyline
and
PTT
circuits will
be
activated,
the PTT line
will wait about
0.5 seconds
before
opening
for convenience.
The PTT line
is not activated
by
the
manual
key.
BAUDOT KEYBOARD:
Connect
a cable from
the
loop
circuit of
your
printer
and TU
(Terminal
Unit or
modulator/demodulator)
to
the
jack
marked
"LOOP" on the KB—4900.
This
jack
is isolated
From
the chassis
and the internal
circuitry
of the
KB—4900. It
will work
with either
polarity
o{ dc and
is rated to
key
up
to 300
Vdc at
l00 mA max.
Host amateur
loops
are
approximately
l9O
Vdc at 60 mA.
Make sure the
TU
loop
is
deactivated
during
hook-up,
otherwise
the 190 Vdc
will
appear
at the
exposed
end of
the
loop
plug
causing
a
potential
electrical
shock.
Also,
connect a cable
from the
PTT line and
keyline
of
your
transmitter
to the
respective
jacks
on the rear
of the KB-4900 (PTT
to
"PTT",
KEYLINE to
"XHTR”.
To
go
to the Baudot
mode, type
ETRL-2.
Now, typing
on the
keyboard
will
key
the
loop
circuit.
To
go
on the
air,
place
the “TUNE/DP/SELF~TEST"
switch in TUNE
before
starting
transmission.
This will close
both the
keyline
and PTT circuits
placing
your
transmitter in
the RTTY mode
where the
characters
are transmitted
by
FSK
(Frequency
Shift
Keying).
Type
just
as on
a normal
typewriter,
all
LTRS and FIGS shifts
are done
For
you
automatically
in addition
to all end~of-line
carriage
returns
and line feeds.
At the end
of
your
transmission,
return the
"TUNEIOPI
SELF—TEST"
to "UP".
Note that at the
beginning
and end
of
your
transmission
and at ten
minute intervals
during
the
transmission, you
are
required
to
send
your
call
letter identification.
Pressing
the
"ID"
key
will
send
the ID
in
RTTY, pressing
"SHIFT/ID“ will
send
your
CH ID
over the
loop
circuit.
This assumes
you
have loaded
your
call
letters into
message
"A" as described
in the GENERAL
OPERATION section.
If
you
experiment
with the code
speed,
you
will find a
speed
(around 13
wpn
for Baudot)
where the
printer
will
print
all O’s
during
the
ID.
I¥
you
want KDS
(Keyboard
Operated
Switch)
carrier
control,
connect
the
KB-4900 PTT
output
to control
your
transmitter
keyline
and/or
PTT
line,
a
0.5 second
delay
on
PTT
dropout
will
allow
momentary
pauses.
You
will need to "diddle"
with
the "LTRS"
key
to
prevent
dropout
otherwise.
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