FCC Technician Class Exam Study Guide - 2014-2018/Subelement T9 Group B
Feed lines: types of feed lines; attenuation vs. frequency; SWR concepts; matching; weather protection; choosing RF connectors and feed lines
The Question Pool
[edit | edit source]Question 1
[edit | edit source]- Why is it important to have a low SWR in an antenna system that uses coaxial cable feed line?
- A. To reduce television interference
- B. To allow the efficient transfer of power and reduce losses
- C. To prolong antenna life
- D. All of these choices are correct
The correct answer is B.
Question 2
[edit | edit source]- What is the impedance of the most commonly used coaxial cable in typical amateur radio installations?
- A. 8 ohms
- B. 50 ohms
- C. 600 ohms
- D. 12 ohms
The correct answer is B.
Question 3
[edit | edit source]- Why is coaxial cable used more often than any other feed line for amateur radio antenna systems?
- A. It is easy to use and requires few special installation considerations
- B. It has less loss than any other type of feed line
- C. It can handle more power than any other type of feed line
- D. It is less expensive than any other types of feed line
The correct answer is A.
Question 4
[edit | edit source]- What does an antenna tuner do?
- A. It matches the antenna system impedance to the transceiver's output impedance
- B. It helps a receiver automatically tune in weak stations
- C. It allows an antenna to be used on both transmit and receive
- D. It automatically selects the proper antenna for the frequency band being used
The correct answer is A.
Question 5
[edit | edit source]- What generally happens as the frequency of a signal passing through coaxial cable is increased?
- A. The apparent SWR increases
- B. The reflected power increases
- C. The characteristic impedance increases
- D. The loss increases
The correct answer is D.
Question 6
[edit | edit source]- Which of the following connectors is most suitable for frequencies above 400 MHz?
- A. A UHF (PL-259/SO-239) connector
- B. A Type N connector
- C. An RS-213 connector
- D. A DB-25 connector
The correct answer is B.
Question 7
[edit | edit source]- Which of the following is true of PL-259 type coax connectors?
- A. They are preferred for microwave operation
- B. They are water tight
- C. They are commonly used at HF frequencies
- D. They are a bayonet type connector
The correct answer is C.
Question 8
[edit | edit source]- Why should coax connectors exposed to the weather be sealed against water intrusion?
- A. To prevent an increase in feed line loss
- B. To prevent interference to telephones
- C. To keep the jacket from becoming loose
- D. All of these choices are correct
The correct answer is A.
Question 9
[edit | edit source]- What might cause erratic changes in SWR readings?
- A. The transmitter is being modulated
- B. A loose connection in an antenna or a feed line
- C. The transmitter is being over-modulated
- D. Interference from other stations is distorting your signal
The correct answer is B.
Question 10
[edit | edit source]- What electrical difference exists between the smaller RG-58 and larger RG-8 coaxial cables?
- A. There is no significant difference between the two types
- B. RG-58 cable has less loss at a given frequency
- C. RG-8 cable has less loss at a given frequency
- D. RG-58 cable can handle higher power levels
The correct answer is C.
Question 11
[edit | edit source]- Which of the following types of feed line has the lowest loss at VHF and UHF?
- A. 50-ohm flexible coax
- B. Multi-conductor unbalanced cable
- C. Air-insulated hard line
- D. 75-ohm flexible coax
The correct answer is C.