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CHOOSING
AN
ANTENNA
To calcuate antenna
length
for a
specific
frequency
Refer
to
the following charts. The first
chart indicates the length of wire
re-
quired for optimum performance on the
Wave Length - Ham Band
160 meter
80 meter
40 meter
20
meter
15 meter
=30 1/2 feet
specified band. The second chart gives
you
the required length of wire to receive
the amateur radio operator's bands.
Antenna Wire Length (feet)
1440 Lengths generally
441 impractical to erect
153
57
22
Length of a 1/2 wave antenna
=
468000
246
117
66
33
22
Antenna Wire Length (feet)
This formula results
in
a half-wave
antenna.
Desired Frequency (kHz)
For example, to pick up international
shortwave signals
in
the
19
meter band,
15100 to 15600 kHz, pick a represen-
tative frequency, such as 15350 kHz.
The formula then becomes:
468000
15350
500 kHz
1600 kHz
4500 kHz
12000 kHz
29999 kHz
150 kHz
520 kHz
1600 kHz
4500 kHz
12000 kHz
Frequency
You can determine the exact length of
wire you need for a specific frequency
using the following information. Then,
obtain bare copper wire, stand-off in-
sulators, and
an
appropriate length of
lead-in wire. Be sure to use a static
discharge unit
to
guard against lightning
damage. For complete information,
refer to
The
Radio Amateur Handbook,
published by the American Radio
Relay League.
• Use a combination TV/FM antenna.
A general purpose shortwave antenna,
such as Cat. No. 278-758, can provide
better reception than either of the built-
in antennas. However, if you want the
best possible reception on one specific
band, your antenna must
be
a certain
length.
Note
eTo
use
an
external antenna,
equipped with 300-ohm twinlead,
connect the twinlead's terminals
to
a 300
to
75-ohm matching trans-
former, Cat. No. 15-1253.
Then insert the 75-ohm connector
of
the
transformer into
an
F-to-RCA
adapter, Cat. No. 278-252.
Finally, insert the RCA type plug
of the adapter into the RCA antenna
jack of the receiver.
Be
sure
to
move
the
antenna
switch to EXT.
•
If
your antenna uses
75
ohm coaxial
cable, attach the connector of the
cable
to
Cat.
No.
278-252, which also
terminates
in
a RCA type plug.
In-
sert the
RCA
plug into the ANT jack,
and move the switch next to the jack
to EXT.
AM - SHORTWAVE BANDS
For
AM
reception, you can use many
different types of antennas. Unfor-
tunately, no single antenna can effec-
tively cover
the
entirefrequency range
of the DX-440, from 150 kHz to 29999
kHz.
~
.}>
.
n,,-
.
......
-
The radio uses a telescoping antenna
and
an
internal ferrite bar antenna for
reception of signals between 150 kHz
and 1620 kHz. These antennas provide
acceptable reception for most situa-
tions. However, if you use
an
external
antenna,
you
can receive more signals,
and the signals you receive will
be
better.
FM BAND
• Use
an
outdoor
FM
antenna. This
type, specially designed for optimum
FM
performance, requires rooftop (or
similar location) mounting.
• Use a set of VHF-TV rabbit ears.
Those made for
TV
/FM coverage
can
help get better performance on the
FM
band.
34
35