T7_Practical_Circuits_part_2

What is the primary purpose of a dummy load?

• To prevent transmitting signals over the air when making tests
• To prevent over-modulation of a transmitter
• To improve the efficiency of an antenna
• To improve the signal-to-noise ratio of a receiver

Which of the following is used to determine if an antenna is resonant at the desired operating frequency?

• A VTVM
• An antenna analyzer
• A Q meter
• A frequency counter

What does a dummy load consist of?

• A high-gain amplifier and a TR switch
• A non-inductive resistor mounted on a heat sink
• A low-voltage power supply and a DC relay
• A 50-ohm reactance used to terminate a transmission line

What reading on an SWR meter indicates a perfect impedance match between the antenna and the feed line?

• 2 days, 2:50:00
• Zero
• 1:1
• Full Scale

Why do most solid-state transmitters reduce output power as SWR increases beyond a certain level?

• To protect the output amplifier transistors
• To comply with FCC rules on spectral purity
• Because power supplies cannot supply enough current at high SWR
• To lower the SWR on the transmission line

What does an SWR reading of 4:1 indicate?

• Loss of -4 dB
• Good impedance match
• Gain of +4 dB
• Impedance mismatch

What happens to power lost in a feed line?

• It increases the SWR
• It is radiated as harmonics
• It is converted into heat
• It distorts the signal

Which instrument can be used to determine SWR?

• Voltmeter
• Ohmmeter
• Iambic pentameter
• Directional wattmeter

Which of the following causes failure of coaxial cables?

• Moisture contamination
• Solder flux contamination
• Rapid fluctuation in transmitter output power
• Operation at 100% duty cycle for an extended period

Why should the outer jacket of coaxial cable be resistant to ultraviolet light?

• Ultraviolet resistant jackets prevent harmonic radiation
• Ultraviolet light can increase losses in the cable’s jacket
• Ultraviolet and RF signals can mix, causing interference
• Ultraviolet light can damage the jacket and allow water to enter the cable