Realistic DX-440 warranty Choosing AN Antenna, FM Band, AM Shortwave Bands

CHOOSING AN ANTENNA

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 a set of VHF-TV rabbit ears. Those made for TV/FM coverage can help get better performance on the FM band.

•Use an outdoor FM antenna. This type, specially designed for optimum FM performance, requires rooftop (or similar location) mounting.

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• Use a combination TV/FM antenna.

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 entire frequency range of the DX-440, from 150 kHz to 29999 kHz.

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.

Refer to the following charts. The first chart indicates the length of wire re- quired for optimum performance on the

Frequency
150 kHz	500	kHz
520 kHz	1600 kHz
1600 kHz	4500	kHz
4500 kHz	12000 kHz
12000 kHz	29999	kHz

Wave Length - Ham Band

160meter

80meter

40meter

20meter

15meter

To calcuate antenna length for a specific 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.

specified band. The second chart gives you the required length of wire to receive the amateur radio operator'sbands.

Antenna Wire Length (feet)

1440 Lengths generally

441impractical to erect

57

22

Antenna Wire Length (feet)

246

117

66

33

22

This formula results in a half-wave antenna.

Length of a 1/2 wave antenna = 468000

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	= 30 1/2 feet
15350

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