antenna,
can
provide
a
quality
signal
for the
TX-11
b.
Even
in
"fringe
areas"
where good reception
is
normally
a
real problem.
Be
sure
any
mast
or
tower set-up
is
properly secured with
guy
wire supports
(if
needed),
and
installed where
it
can't fall into power lines,
the
neighbor's greenhouse,
or
whatever.
Cable
When
we
talk about cable,
we
mean
a
master antenna system
supplying
high
quality
TV and
FM
signals
to
individual
homes
(or
"subscribers").
The
signals
are
sent
via a
distribution network
of
wires
and
line amplifiers.
The
wire,
or
cable portion
of the
system,
can be
likened
to a
telephone distribution set-up.
The
line amplifiers
are
used
to
boost signals
at
certain intervals
in the
lines, much like using
an
antenna
preamp with long feedlines
in
your
own
antenna system.
Originally,
community cable television
(CATV)
was a
response
to the
problems
of
poor
or
nonexistant reception
of TV
signals broadcast
"clear
air." These problems could
be
caused
by
distance, terrain,
or
even
just
remote locations (out
of
range,
or
fringe area reception).
The
cable company chooses
a
high hilltop
or
other location where
they
can
obtain
the
best
line-of-sight
to the
area's transmitting towers.
This site
is
known
in
cable parlance
as the
"head end." This
is
where
high-gain
antennas
and
amplifiers
are
used
to
receive distant, weak,
or
otherwise
unreceivable
signals.
The
signals
are
passed
on to
line
transmitters,
then
to the
distribution part
of the
cable system.
At
your home, signals from
the
cable
in the
street
are fed to
your
TV
set.
If you
want
FM as
well
as TV, the
signals
are
split
with
one set
going
to the TV, the
other
to
your
TX-11
b. Of
course,
you can be
connected
to
just receive
FM
signals,
without
the
video hook-up.
An
FM
feed
may use a
special filter
to
remove
TV
interference,
or to
prevent
you
from
illegally
receiving
FM
signals
from
a
single
TV
feed,
an
FM
trap might
be
installed
at the
street. When
the
cable people
connect your
TX-11
b to the
system,
any
necessary
filters
are
installed,
any
traps
are
removed from
the
line. This brings
up
something else
again:
it's
not
legal
to tap
into,
or
hook
a
commercial cable
up
yourself.
It
must
be
done
by the
cable company.
As
mentioned earler
in
this manual, feedlines
for
cable
TV are all 75 fl
coaxial cable,
so
connections
can be
made directly
to the
TX-11
b's
75
ft
antenna input. However,
the
usual procedure
is for the
cable
company installer
to
connect
a
tuner with
a
matching transformer
(75
ft to 300 ft) to its 300 ft
inputs.
As we
suggested,
ask the
installer
if
it
would
be
possible
to use the
TX-11
b's 75 ft
input.
The
benefits
of
using
a
commercial cable
to
supply high quality
FM
stereo
signals
for the
TX-11
b are
many.
For
example,
you
don't have
to
worry
about
the
cost
and
effort
of
installing
a
good outdoor antenna.
You
don't have
to
worry
about
the
performance
of
such
a
system
after
all
that work, either.
As a
rule, cable companies have
a
one-time
installation charge, then
a
monthly fee.
The
cost
of
cable service
can
depend
on
many factors,
and
varies from system
to
system. Costs
will
run
higher
for a
commercial
cable
feed
for
both
TV and FM
service,
less
for FM
only.
Other
than opening
up a new
world
for
enjoyment
of FM
programming,
commercial cable
can
open
a new
world
of
audio
for
your
TV
set. Many
cable
systems program premium movie/film services with
spectacular
stereo
soundtracks.
The
video portion (with standard audio carrier)
is
broadcast
on the
cable
for the TV
set.
A
separate stereo soundtrack
is
broadcast
in the FM
band.
The
TX-11
b
receives these signals
and
turns your
living
room
into
a
real
theater
or
concert
hall.
You not
only
see
great artists performing your favorite music,
but
hear
it
like
you
were there. This set-up frees your
TV
from
its
burden
of
having
a
tiny,
limited-response, internal audio
amp and
speaker.
AM
Antennas
The
Motorola
CQUAM™
AM
stereo system requires
a
stronger
and
cleaner signal
to
take full advantage
of the
benefits
of AM
stereo.
Two
AM
antennas
are
included with your
TX-11
b: a
long wire antenna
and
a
loop antenna.
We
have detailed
the
benefits
of
each type
to
help
you
select
the
best antenna
for
your environment.
AM
Wire Antenna
The
long wire antenna
is,
under most circumstances,
the
preferred
antenna.
It is
able
to
receive signals from farther away
and
will receive
normally
distant signals much stronger than
the
small loop antenna.
This wire antenna
is
also more effective
for
eliminating noises that
occur
in in the
atmosphere that
is at a
distance from
the
tuner.
The
long
wire
orientation
is not
particularly critical. Since this antenna
is
used
for
maximum sensitivity,
if you
live very close
to a
strong
transmitter
you may
overload
the
front
end of
your tuner with this
antenna
and
will want
to try the
loop antenna.
AM
Loop Antenna
There
are
certain conditions
in
which
the
loop antenna works best.
It
has
better noise rejection
for
locally generated noise
-
noises that
are
generated close
to the
tuner
and may
sound like buzzes
or
hum.
It is
able
to
reduce these noises
for two
reasons:
1)
This antenna
is
directional,
and 2) it has a
lower driving impedance than
the
wire,
so
it
tends
to
short
circuit
this
kind
of
interference
readily.
The
loop antenna picks
up the
signal
at
right angle
to an
axis passed
through
the
loop.
If you
want
to
pick
up a
radio station that
is due
north,
orient
an
axis that passes through
the
loop
at
right angles
to
north.
If
you
were holding this antenna
as if it
were
a
gun,
you
would point
it
at
the
station. Again,
the
loop antenna
is for
maximum rejection
of
locally
generated
interference.
Ultimate
AM
Antenna
For
those
of you who
would like
to
take
the
time
to
build
the
ultimate
AM
antenna,
we
offer
the
plans that follow. This antenna incorporates
the
benefits
of
both
the
wire
and the
small loop.
It
will have
the
noise
reduction capability
of the
small loop
for
locally
generated
noise,
the
noise
reduction capability
of the
wire
for
atmospherically generated
noise,
it
will
be
extremely
sensitive,
and it
will
be
very
directional.
This antenna
is
basically
a
home-built
loop
whose area
is
measured
in
square feet rather than square inches.
To
build this antenna:
1)
Construct
a
wood cross frame that measures
12"
from
point
to
16
I
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