T9B-2010: Feedlines; types, losses vs. frequency, SWR concepts, matching, weather protection, connectors
T9B01:
Why is it important to have a low SWR in an antenna system that uses coaxial cable feedline?
To allow the efficient transfer of power and reduce losses
To reduce television interference
To prolong antenna life
All of these choices are correct
T9B02:
What is the impedance of the most commonly used coaxial cable in typical amateur radio installations?
50 ohms
8 ohms
600 ohms
12 ohms
T9B03:
Why is coaxial cable used more often than any other feedline for amateur radio antenna systems?
It is easy to use and requires few special installation considerations
It has less loss than any other type of feedline
It can handle more power than any other type of feedline
It is less expensive than any other types of feedline
T9B04:
What does an antenna tuner do?
It matches the antenna system impedance to the transceiver’s output impedance
It helps a receiver automatically tune in weak stations
It allows an antenna to be used on both transmit and receive
It automatically selects the proper antenna for the frequency band being used
T9B05:
What generally happens as the frequency of a signal passing through coaxial cable is increased?
The loss increases
The apparent SWR increases
The reflected power increases
The characteristic impedance increases
T9B06:
Which of the following connectors is most suitable for frequencies above 400 MHz?
A Type N connector
A UHF (PL-259/SO-239) connector
An RS-213 connector
A DB-23 connector
T9B07:
Which of the following is true of PL-259 type coax connectors?
The are commonly used at HF frequencies
They are good for UHF frequencies
They are water tight
They are a bayonet type connector
T9B08:
Why should coax connectors exposed to the weather be sealed against water intrusion?
To prevent an increase in feedline loss
To prevent interference to telephones
To keep the jacket from becoming loose
All of these choices are correct
T9B09:
What might cause erratic changes in SWR readings?
A loose connection in an antenna or a feedline
The transmitter is being modulated
The transmitter is being over-modulated
Interference from other stations is distorting your signal
T9B10:
What electrical difference exists between the smaller RG-58 and larger RG-8 coaxial cables?
RG-8 cable has less loss at a given frequency
There is no significant difference between the two types
RG-58 cable has less loss at a given frequency
RG-58 cable can handle higher power levels
T9B11:
Which of the following types of feedline has the lowest loss at VHF and UHF?
Air-insulated hard line
50-ohm flexible coax
Multi-conductor unbalanced cable
75-ohm flexible coax
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