Radio Shack CCR-81 Technical Reference Manual

TV SWITCH
BOX
The
antenna
switch
box
consists of
a switch
and
a balun,
with
connectors
provided for
attachment
to the
computer,
the
TV
antenna,
and the
home
TV.
The switch
box
is
connected
to
the
customer's
TV,
through
the
300 ohm twin
lead
output.
The
TV antenna
is attached
directly
to the switch
box.
The
computer
output
is connected
through
a
75
ohm
coax
cable
to
the phone
plug input
on the
switch box. Figure
17 shows
a
schematic
of
the antenna switch
box.
From
the
computer,
the
signal
is
connected
to a balun
in the
switch
box,
which
matches
the
modulator's
75
ohm
output
impedance
to
a TV's
300
ohm
antenna
input
impedance.
This
signal
is
then connected
to the
switch.
The
switch
is specially
designed
to
provide the
60dB of
isolation
required
between
the computer
and the
TV
antenna.
COMPUTER
INPUT
r
_r
V
.HniWiiMi.jTi
*
,-QAOOO
r
BALUN
60 dB
SWITCH
J
t
Kj
U>Q-
ATTENNA
INPUT
>~
300 ohm
>
~Q4
<
TWIN
LEAD OUTPUT
TO THE
TV
3
FIGURE
17. ANTENNA
SWITCH
BOX
SCHEMATIC
41

Radio Shack CCR-81 Specifications

General

Brand	Radio Shack
Model	CCR-81
Category	Desktop
Language	English