3.1 KiB
T9B – Feed lines: types, attenuation vs frequency, selecting; SWR concepts; Antenna tuners (couplers); RF Connectors: selecting, weather protection
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T9B01 (B) What is a benefit of low SWR? #card
- A. Reduced television interference
- B. Reduced signal loss
- C. Less antenna wear
- D. All these choices are correct
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T9B02 (B) What is the most common impedance of coaxial cables used in amateur radio? #card
- A. 8 ohms
- B. 50 ohms
- C. 600 ohms
- D. 12 ohms
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T9B03 (A) Why is coaxial cable the most common feed line for amateur radio antenna systems? #card
- 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 type of feed line
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T9B04 (A) What is the major function of an antenna tuner (antenna coupler)? #card
- 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
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T9B05 (D) What happens as the frequency of a signal in coaxial cable is increased? #card
- A. The characteristic impedance decreases
- B. The loss decreases
- C. The characteristic impedance increases
- D. The loss increases
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T9B06 (B) Which of the following RF connector types is most suitable for frequencies above 400 MHz? #card
- A. UHF (PL-259/SO-239)
- B. Type N
- C. RS-213
- D. DB-25
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T9B07 (C) Which of the following is true of PL-259 type coax connectors? #card
- A. They are preferred for microwave operation
- B. They are watertight
- C. They are commonly used at HF and VHF frequencies
- D. They are a bayonet-type connector
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T9B08 (D) Which of the following is a source of loss in coaxial feed line? #card
- A. Water intrusion into coaxial connectors
- B. High SWR
- C. Multiple connectors in the line
- D. All these choices are correct
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T9B09 (B) What can cause erratic changes in SWR? #card
- A. Local thunderstorm
- B. Loose connection in the antenna or feed line
- C. Over-modulation
- D. Overload from a strong local station
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T9B10 (C) What is the electrical difference between RG-58 and RG-213 coaxial cable? #card
- A. There is no significant difference between the two types
- B. RG-58 cable has two shields
- C. RG-213 cable has less loss at a given frequency
- D. RG-58 cable can handle higher power levels
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T9B11 (C) Which of the following types of feed line has the lowest loss at VHF and UHF? #card
- A. 50-ohm flexible coax
- B. Multi-conductor unbalanced cable
- C. Air-insulated hardline
- D. 75-ohm flexible coax
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T9B12 (A) What is standing wave ratio (SWR)? #card
- A. A measure of how well a load is matched to a transmission line
- B. The ratio of amplifier power output to input
- C. The transmitter efficiency ratio
- D. An indication of the quality of your station’s ground connection