Feed lines and connectors Flashcards
Why is coaxial cable the most common feed line selected for amateur radio antenna systems? (T9B03)
It is easy to use and requires few special installation considerations
What is impedance? (T5C12)
A measure of the opposition to AC current flow in a circuit
What is a unit of impedance? (T5C13)
Ohms
What is the impedance of most coaxial cables used in amateur radio installations? (T9B02)
50 ohms
In general, what happens as the frequency of a signal passing through coaxial cable is increased? (T9B05)
The loss increases
What is the electrical difference between RG-58 and RG-8 coaxial cable? (T9B10)
RG-8 cable has less loss at a given frequency
Which of the following types of feed line has the lowest loss at VHF and UHF? (T9B11)
Air-insulated hard line
Which of the following is the most common cause for failure of coaxial cables? (T7C09)
Moisture contamination
Why should the outer jacket of coaxial cable be resistant to ultraviolet light? (T7C10)
Ultraviolet light can damage the jacket and allow water to enter the cable
What is a disadvantage of air core coaxial cable when compared to foam or solid dielectric types? (T7C11)
It requires special techniques to prevent water absorption
Which of the following is true of PL-259 type coax connectors? (T9B07)
They are commonly used at HF frequencies
Which of the following connectors is most suitable for frequencies above 400 MHz? (T9B06)
A type N Connector
Why should coax connectors exposed to the weather be sealed against water intrusion? (T9B08)
To prevent an increase in feed line loss
What can cause erratic changes in SWR readings? (T9B09)
A loose connection in an antenna or a feed line
