Which of the following might be useful in reducing RF interference to audio frequency circuits?

1. A Bypass inductor
2. B Bypass capacitor
3. C Forward-biased diode
4. D Reverse-biased diode

Which of the following could be a cause of interference covering a wide range of frequencies?

1. A Not using a balun or line isolator to feed balanced antennas
2. B Lack of rectification of the transmitter's signal in power conductors
3. C Arcing at a poor electrical connection
4. D Using a balun to feed an unbalanced antenna

What sound is heard from an audio device experiencing RF interference from a single sideband phone transmitter?

1. A A steady hum whenever the transmitter is on the air
2. B On-and-off humming or clicking
3. C Distorted speech
4. D Clearly audible speech

What sound is heard from an audio device experiencing RF interference from a CW transmitter?

1. A On-and-off humming or clicking
2. B A CW signal at a nearly pure audio frequency
3. C A chirpy CW signal
4. D Severely distorted audio

What is a possible cause of high voltages that produce RF burns?

1. A Flat braid rather than round wire has been used for the ground wire
2. B Insulated wire has been used for the ground wire
3. C The ground rod is resonant
4. D The ground wire has high impedance on that frequency

What is a possible effect of a resonant ground connection?

1. A Overheating of ground straps
2. B Corrosion of the ground rod
3. C High RF voltages on the enclosures of station equipment
4. D A ground loop

Why should soldered joints not be used in lightning protection ground connections?

1. A A soldered joint will likely be destroyed by the heat of a lightning strike
2. B Solder flux will prevent a low conductivity connection
3. C Solder has too high a dielectric constant to provide adequate lightning protection
4. D All these choices are correct

Which of the following would reduce RF interference caused by common-mode current on an audio cable?

1. A Place a ferrite choke on the cable
2. B Connect the center conductor to the shield of all cables to short circuit the RFI signal
3. C Ground the center conductor of the audio cable causing the interference
4. D Add an additional insulating jacket to the cable

How can the effects of ground loops be minimized?

1. A Connect all ground conductors in series
2. B Connect the AC neutral conductor to the ground wire
3. C Avoid using lock washers and star washers when making ground connections
4. D Bond equipment enclosures together

What could be a symptom caused by a ground loop in your station's audio connections?

1. A You receive reports of "hum" on your station's transmitted signal
2. B The SWR reading for one or more antennas is suddenly very high
3. C An item of station equipment starts to draw excessive amounts of current
4. D You receive reports of harmonic interference from your station

What technique helps to minimize RF "hot spots" in an amateur station?

1. A Building all equipment in a metal enclosure
2. B Using surge suppressor power outlets
3. C Bonding all equipment enclosures together
4. D Placing low-pass filters on all feed lines

Why must all metal enclosures of station equipment be grounded?

1. A It prevents a blown fuse in the event of an internal short circuit
2. B It prevents signal overload
3. C It ensures that the neutral wire is grounded
4. D It ensures that hazardous voltages cannot appear on the chassis