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Assignment 19

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 

T7C01 What is the primary purpose of a dummy load?
a.
To prevent the radiation of signals when making tests
c.
To improve the radiation from your antenna
b.
To prevent over-modulation of your transmitter
d.
To improve the signal to noise ratio of your receiver
 

 2. 

T7C02 Which of the following instruments can be used to determine if an antenna is resonant at the desired operating frequency?
a.
A VTVM
c.
A Q meter
b.
An antenna analyzer
d.
A frequency counter
 

 3. 

T7C03 What, in general terms, is standing wave ratio (SWR)?
a.
A measure of how well a load is matched to a transmission line
c.
The transmitter efficiency ratio
b.
The ratio of high to low impedance in a feed line
d.
An indication of the quality of your station’s ground connection
 

 4. 

T7C04 What reading on an SWR meter indicates a perfect impedance match between the antenna and the feed line?
a.
2 to 1
c.
1 to 1
b.
1 to 3
d.
10 to 1
 

 5. 

T7C05 What is the approximate SWR value above which the protection circuits in most solid-state transmitters begin to reduce transmitter power?
a.
2 to 1
c.
6 to 1
b.
1 to 2
d.
10 to 1
 

 6. 

T7C06 What does an SWR reading of 4:1 indicate?
a.
Loss of -4dB
c.
Gain of +4dB
b.
Good impedance match
d.
Impedance mismatch
 

 7. 

T7C07 What happens to power lost in a feed line?
a.
It increases the SWR
c.
It is converted into heat
b.
It comes back into your transmitter and could cause damage
d.
It can cause distortion of your signal
 

 8. 

T7C08 What instrument other than an SWR meter could you use to determine if a feed line and antenna are properly matched?
a.
Voltmeter
c.
Iambic pentameter
b.
Ohmmeter
d.
Directional wattmeter
 

 9. 

T7C09 Which of the following is the most common cause for failure of coaxial cables?
a.
Moisture contamination
c.
The velocity factor exceeds 1.0
b.
Gamma rays
d.
Overloading
 

 10. 

T7C10 Why should the outer jacket of coaxial cable be resistant to ultraviolet light?
a.
Ultraviolet resistant jackets prevent harmonic radiation
c.
Ultraviolet and RF signals can mix together, causing interference
b.
Ultraviolet light can increase losses in the cable’s jacket
d.
Ultraviolet light can damage the jacket and allow water to enter the cable
 

 11. 

T7C11 What is a disadvantage of air core coaxial cable when compared to foam or solid dielectric types?
a.
It has more loss per foot
c.
It requires special techniques to prevent water absorption
b.
It cannot be used for VHF or UHF antennas
d.
It cannot be used at below freezing temperatures
 

 12. 

T7C12 Which of the following is a common use of coaxial cable?
a.
Carrying dc power from a vehicle battery to a mobile radio
c.
Securing masts, tubing, and other cylindrical objects on towers
b.
Carrying RF signals between a radio and antenna
d.
Connecting data signals from a TNC to a computer
 

 13. 

T7C13 What does a dummy load consist of?
a.
A high-gain amplifier and a TR switch
c.
A low voltage power supply and a DC relay
b.
A non-inductive resistor and a heat sink
d.
A 50 ohm reactance used to terminate a transmission line
 

 14. 

T9B01 Why is it important to have a low SWR in an antenna system that uses coaxial cable feed line?
a.
To reduce television interference
c.
To prolong antenna life
b.
To allow the efficient transfer of power and reduce losses
d.
All of these choices are correct
 

 15. 

T9B02 What is the impedance of the most commonly used coaxial cable in typical amateur radio installations?
a.
8 ohms
c.
600 ohms
b.
50 ohms
d.
12 ohms
 

 16. 

T9B03 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
c.
It can handle more power than any other type of feed line
b.
It has less loss than any other type of feed line
d.
It is less expensive than any other types of feed line
 

 17. 

T9B04 What does an antenna tuner do?
a.
It matches the antenna system impedance to the transceiver's output impedance
c.
It allows an antenna to be used on both transmit and receive
b.
It helps a receiver automatically tune in weak stations
d.
It automatically selects the proper antenna for the frequency band being used
 

 18. 

T9B05 What generally happens as the frequency of a signal passing through coaxial cable is increased?
a.
The apparent SWR increases
c.
The characteristic impedance increases
b.
The reflected power increases
d.
The loss increases
 

 19. 

T9B06 Which of the following connectors is most suitable for frequencies above 400 MHz?
a.
A UHF (PL-259/SO-239) connector
c.
An RS-213 connector
b.
A Type N connector
d.
A DB-25 connector
 

 20. 

T9B07 Which of the following is true of PL-259 type coax connectors?
a.
They are preferred for microwave operation
c.
They are commonly used at HF frequencies
b.
They are water tight
d.
They are a bayonet type connector
 

 21. 

T9B08 Why should coax connectors exposed to the weather be sealed against water intrusion?
a.
To prevent an increase in feed line loss
c.
To keep the jacket from becoming loose
b.
To prevent interference to telephones
d.
All of these choices are correct
 

 22. 

T9B09 What might cause erratic changes in SWR readings?
a.
The transmitter is being modulated
c.
The transmitter is being over-modulated
b.
A loose connection in an antenna or a feed line
d.
Interference from other stations is distorting your signal
 

 23. 

T9B10 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
c.
RG-8 cable has less loss at a given frequency
b.
RG-58 cable has less loss at a given frequency
d.
RG-58 cable can handle higher power levels
 

 24. 

T9B11 Which of the following types of feed line has the lowest loss at VHF and UHF?
a.
50-ohm flexible coax
c.
Air-insulated hard line
b.
Multi-conductor unbalanced cable
d.
75-ohm flexible coax
 



 
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