AMC XTa, Инструкция по установке и эксплуатации

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12
NOTES ON ANTENNAS
In most cases, the exceptional sensitivity of AMC tuner circuits results in achieving very good
performance with only a ribbonwire dipole antenna. However there are limitations to a dipole. It is not
effective at rejecting multipath distortion and other forms of FM interference and it cannot easily be
oriented for optimizing its reception pattern. Other possible solutions, in order of increasing cost, include:
1. Indoor TV antenna (rabbitears) without extra coils or tuning switches
* Will NOT improve the strength of weak signals.
* Has solid metal tuned elements that can be rotated.
* The two elements should be extended to a total length of 30 inches (75cm) and oriented horizontally
or at a shallow angle less than 45 degrees upward.
* The antenna connecting wire should be connected to the tuner 75 Ohm antenna terminal using the
matching transformer included in the tuner accessory package.
* After selecting a station, rotate the antenna for best reception.
2. Indoor TV antenna (rabbitears) with a tuning switch
* Will NOT improve the strength of weak signals.
* May reduce some types of FM interference, such as reflected multipath signals.
3. Electrically tuned indoor antenna
* Will NOT improve the strength of weak signals.
* May further reduce some types of FM interference, such as reflected multipath signals.
4. Outdoor antenna
* Provides largest selection of stations and best reception with lowest noise and distortion.
* Narrower directional pattern more effectively rejects reflected multipath signals.
* Signal strength is directly proportional to the antenna height above the ground.
* May be mounted to a tall mast or to a roof.
* Because TV antennas are purposely designed to be weak at FM frequencies, to lessen interference
to TV signals, a directional FM only antenna will provide best results.
* FM only antenna should be mounted as high above ground as practical and at least two meters (7
feet), both horizontally and vertically away from other antennas.
* Can be mounted on a rotor to allow aiming at stations located in different directions (more than 90
degrees apart).
* Use shielded lead in wire rather than plain "twinlead" wire for better performance, longer life and
protection from the weather.
* Disconnect any indoor antenna from the tuner before connecting the outdoor antenna.
CAUTIONS:
* Avoid power lines when locating and installing antenna
* Include a lightning arrestor in the installation to protect both yourself and the tuner from potential
danger during electrical storms.
OUTDOOR AM ANTENNA
* To improve AM reception, a "longwire" outdoor AM antenna may be installed.
* A "longwire" antenna is simply a straight wire which may vary in length from a few feet up to about
100 feet (30 meters).
* Must be mounted parallel to the earth and should be located as high above the ground as convenient.
* Connect to the tuner at the AM antenna terminal.
* Connect another wire from the Ground terminal to a true "earth" ground, such as a copperplated rod
driven several feet into the earth. Alternate grounds include a coldwater pipe, a steam radiator or
even the third hole of a modern electrical wall socket.