General G4E: Mobile and solar power
These are the 11 official questions in group G4E of the 2023–2027 General question pool, with the correct answer marked and a plain-English explanation of why it's right. The real exam asks one question from this group.
- G4E01Question 1
What is the purpose of a capacitance hat on a mobile antenna?
- ATo increase the power handling capacity of a whip antenna
- BTo reduce radiation resistance
- CTo electrically lengthen a physically short antenna Correct
- DTo lower the radiation angle
Why: A capacitance hat electrically lengthens a physically short antenna.
- G4E02Question 2
What is the purpose of a corona ball on an HF mobile antenna?
- ATo narrow the operating bandwidth of the antenna
- BTo increase the “Q” of the antenna
- CTo reduce the chance of damage if the antenna should strike an object
- DTo reduce RF voltage discharge from the tip of the antenna while transmitting Correct
Why: A corona ball reduces RF discharge from the antenna tip.
- G4E03Question 3
Which of the following direct, fused power connections would be the best for a 100-watt HF mobile installation?
- ATo the battery using heavy-gauge wire Correct
- BTo the alternator or generator using heavy-gauge wire
- CTo the battery using insulated heavy duty balanced transmission line
- DTo the alternator or generator using insulated heavy duty balanced transmission line
Why: Connect directly to the battery with heavy, fused wire.
- G4E04Question 4
Why should DC power for a 100-watt HF transceiver not be supplied by a vehicle’s auxiliary power socket?
- AThe socket is not wired with an RF-shielded power cable
- BThe socket’s wiring may be inadequate for the current drawn by the transceiver Correct
- CThe DC polarity of the socket is reversed from the polarity of modern HF transceivers
- DDrawing more than 50 watts from this socket could cause the engine to overheat
Why: Auxiliary socket wiring may not handle a 100 W radio's current.
- G4E05Question 5
Which of the following most limits an HF mobile installation?
- A“Picket fencing”
- BThe wire gauge of the DC power line to the transceiver
- CEfficiency of the electrically short antenna Correct
- DFCC rules limiting mobile output power on the 75-meter band
Why: The short antenna's low efficiency is the biggest limit in HF mobile.
- G4E06Question 6
What is one disadvantage of using a shortened mobile antenna as opposed to a full-size antenna?
- AShort antennas are more likely to cause distortion of transmitted signals
- BQ of the antenna will be very low
- COperating bandwidth may be very limited Correct
- DHarmonic radiation may increase
Why: Shortened antennas often have very narrow bandwidth.
- G4E07Question 7
Which of the following may cause receive interference to an HF transceiver installed in a vehicle?
- AThe battery charging system
- BThe fuel delivery system
- CThe control computers
- DAll these choices are correct Correct
Why: Alternators, fuel pumps and onboard computers can all cause noise. All the choices are correct.
- G4E08Question 8
In what configuration are the individual cells in a solar panel connected together?
- ASeries-parallel Correct
- BShunt
- CBypass
- DFull-wave bridge
Why: Solar cells are connected series-parallel for voltage and current.
- G4E09Question 9
What is the approximate open-circuit voltage from a fully illuminated silicon photovoltaic cell?
- A0.02 VDC
- B0.5 VDC Correct
- C0.2 VDC
- D1.38 VDC
Why: A silicon solar cell produces about 0.5 V open-circuit.
- G4E10Question 10
Why should a series diode be connected between a solar panel and a storage battery that is being charged by the panel?
- ATo prevent overload by regulating the charging voltage
- BTo prevent discharge of the battery through the panel during times of low or no illumination Correct
- CTo limit the current flowing from the panel to a safe value
- DTo prevent damage to the battery due to excessive voltage at high illumination levels
Why: The diode keeps the battery from discharging back through the panel in low light.
- G4E11Question 11
What precaution should be taken when connecting a solar panel to a lithium iron phosphate battery?
- AGround the solar panel outer metal framework
- BEnsure the battery is placed terminals-up
- CA series resistor must be in place
- DThe solar panel must have a charge controller Correct
Why: A lithium iron phosphate battery needs a charge controller between it and the panel.