The answer to question G4E07 was changed in this section.
Operating mobile, that is from a car or boat, is an activity enjoyed by many radio amateurs. Amateurs can do almost everything from a mobile station that they can do at a fixed station.
When setting up a mobile station, the first thing to consider is how you are going to supply power to your radios. A direct, fused power connection to the battery using heavy gauge wire would be the best for a 100-watt HF mobile installation. (G4E03) It is best NOT to draw the DC power for a 100-watt HF transceiver from an automobile’s auxiliary power socket because the socket’s wiring may be inadequate for the current being drawn by the transceiver. (G4E04)
One common complaint when operating mobile is that the vehicle’s electronics generate noise that interferes with sensitive HF receivers. All of these choices are correct when talking about what may cause interference to be heard in the receiver of an HF mobile installation in a recent model vehicle (G4E07):
- The battery charging system
- The fuel delivery system
- The vehicle control computer
As you can imagine, mobile antennas for HF operation are always a compromise because they are so short with respect to wavelength. The antenna system is the one thing that most limits the effectiveness of an HF mobile transceiver operating in the 75 meter band. (G4E05) One disadvantage of using a shortened mobile antenna as opposed to a full size antenna is that operating bandwidth may be very limited. (G4E06)
One way to make a physically short antenna resonate on HF is to use a capacitance hat. The purpose of a “capacitance hat” on a mobile antenna is a device to electrically lengthen a physically short antenna. (G4E01)
Finally, because mobile antennas are so short, the voltage at the tip of the antenna may be very high. The purpose of a “corona ball” on a HF mobile antenna is to reduce high voltage discharge from the tip of the antenna. (G4E02)
Some amateurs use solar cells to provide emergency power. The process by which sunlight is changed directly into electricity is called photovoltaic conversion. (G4E08)The approximate open-circuit voltage from a modern, well-illuminated photovoltaic cell is 0.5 VDC. (G4E09)
Some amateurs use photovoltaic cells to recharge storage batteries. These systems often have a series diode is connected between a solar panel and the battery. The reason a series diode is connected between a solar panel and a storage battery being charged by the panel is that the diode prevents self discharge of the battery though the panel during times of low or no illumination. (G4E10)
Some amateurs even use wind power as a power source. One disadvantage of using wind as the primary source of power for an emergency station is that a large energy storage system is needed to supply power when the wind is not blowing. (G4E11)
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