T9C: Feedlines types, losses vs. frequency, SWR concepts, measuring SWR, matching and power transfer, weather protection, feedline failure modes
T9C01:
What, in general terms, is standing wave ratio (SWR)?
A measure of how well a load is matched to a transmitter
The ratio of high to low impedance in a feed line
The transmitter efficiency ratio
An indication of the quality of your station ground connection
T9C02:
What reading on a SWR meter indicates a perfect impedance match between the antenna and the feed line?
1 to 1
2 to 1
1 to 3
10 to 1
T9C03:
What might be indicated by erratic changes in SWR readings?
A loose connection in your antenna or feedline
The transmitter is being modulated
The transmitter is being over modulated
Interference from other stations is distorting your signal
T9C04:
What is the SWR value where the protection circuits in most solid-state transmitters begin to reduce transmitter power?
2 to 1
1 to 2
6 to 1
10 to 1
T9C05:
What happens to the power lost in a feed line?
It is converted into heat by losses in the line
It increases the SWR
It comes back into your transmitter and could cause damage
It can cause distortion of your signal
T9C06:
What instrument other than a SWR meter could you use to determine if your feedline and antenna are properly matched?
Directional wattmeter
Voltmeter
Ohmmeter
Iambic Pentameter
T9C07:
What is the most common reason for failure of coaxial cables?
Moisture contamination
Gamma rays
End of service life
Overloading
T9C08:
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
To keep your signal from changing polarization
T9C09:
What can happen to older coaxial cables that are exposed to weather and sunlight for several years?
Losses can increase dramatically
Nothing, weather and sunlight do not affect coaxial cable
The cable can shrink and break
It will short-circuit
T9C10:
Why is the outer sheath of most coaxial cables black in color?
Black provides protection against ultraviolet damage
It is the cheapest color to use
To see nicks and cracks in the cable
Black cables have less loss
T9C11:
What is the impedance of the most commonly used coaxial cable in typical amateur radio installations?
50 Ohms
8 Ohms
600 Ohms
12 Ohms
T9C12:
Why is coaxial cable used more often than any other feed line 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 line
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