Tandy Color Computer 3 Manual page 18

Installation
Figure
4.
Rear view
of
TV
with twin-lead
and
rabbit
ears antenna.
If
you
are
making
a connection
to
a
TV
with
a
75-Ohm
Coaxial
Lead-in,
obtain
a
special
75-Ohm
to
300-Ohm
matching
transformer
such
as Radio
Shack
Catalog
Number
15-1140.
Connect
your
antenna's
coaxial
cable
lead-in to the transformer, then attach the
transformer's twin-lead
to
the
screw
terminals
on
the
Antenna
Switchbox
(see Figure
5).
Figure
5.
Rear
view of
TV
with
75-Ohm
coaxial
cable.