Chapter 12: Avoiding Interference

What would cause a broadcast AM or FM radio to receive an amateur radio transmission unintentionally?

• The receiver is unable to reject strong signals outside the AM or FM band

• The microphone gain of the transmitter is turned up too high

• The audio amplifier of the transmitter is overloaded

• The deviation of an FM transmitter is set too low

Tags

NGSS.HS-PS4-5

Which of the following can cause radio frequency interference?

• Fundamental overload

• Harmonics

• Spurious emissions

• All these choices are correct

Tags

NGSS.HS-PS4-1

NGSS.HS-PS4-3

Which of the following could you use to cure distorted audio caused by RF current on the shield of a microphone cable?

• Band-pass filter

• Low-pass filter

• Preamplifier

• Ferrite choke

Tags

NGSS.HS-PS4-5

Which of the following can reduce overload of a VHF transceiver by a nearby commercial FM station?

• Installing an RF preamplifier

• Using double-shielded coaxial cable

• Installing bypass capacitors on the microphone cable

• Installing a band-reject filter

Tags

NGSS.HS-ETS1-3

What is a symptom of RF feedback in a transmitter or transceiver?

• Excessive SWR at the antenna connection

• The transmitter will not stay on the desired frequency

• Reports of garbled, distorted, or unintelligible voice transmissions

• Frequent blowing of power supply fuses

Tags

NGSS.HS-PS4-5

How can fundamental overload of a non-amateur radio or TV receiver by an amateur signal be reduced or eliminated?

• Block the amateur signal with a filter at the antenna input of the affected receiver

• Block the interfering signal with a filter on the amateur transmitter

• Switch the transmitter from FM to SSB

• Switch the transmitter to a narrow-band mode

Tags

NGSS.HS-PS4-5

Which of the following actions should you take if a neighbor tells you that your station’s transmissions are interfering with their radio or TV reception?

• Make sure that your station is functioning properly and that it does not cause interference to your own radio or television when it is tuned to the same channel

• Immediately turn off your transmitter and contact the nearest FCC office for assistance

• Install a harmonic doubler on the output of your transmitter and tune it until the interference is eliminated

• All these choices are correct

What should be the first step to resolve non-fiber optic cable TV interference caused by your amateur radio transmission?

• Add a low-pass filter to the TV antenna input

• Add a high-pass filter to the TV antenna input

• Add a preamplifier to the TV antenna input

• Be sure all TV feed line coaxial connectors are installed properly

Tags

NGSS.MS-ETS1-3

Where should the negative power return of a mobile transceiver be connected in a vehicle?

• At the 12 volt battery chassis ground

• At the antenna mount

• To any metal part of the vehicle

• Through the transceiver’s mounting bracket

What should you do if something in a neighbor’s home is causing harmful interference to your amateur station?

• Work with your neighbor to identify the offending device

• Politely inform your neighbor that FCC rules prohibit the use of devices that cause interference

• Make sure your station meets the standards of good amateur practice

• All these choices are correct