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ISED - BASIC Radio Amateur > 008 - Interference and Suppression > Flashcards

008 - Interference and Suppression Flashcards

1
Q

B-008-001-001
What is meant by receiver overload?

(a) Interference caused by turning the volume up too high
(b) Too much current from the power supply
(c) Interference caused by strong signals from a nearby transmitter
(d) Too much voltage from the power supply

A

B-008-001-001
What is meant by receiver overload?

(c) Interference caused by strong signals from a nearby transmitter

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2
Q

B-008-001-002
What is one way to tell if radio frequency interference to a receiver is caused by front-end overload?

(a) If grounding the receiver makes the problem worse
(b) If connecting a low pass filter to the receiver greatly cuts down the interference
(c) If the interference is about the same no matter what frequency is used for the transmitter
(d) If connecting a low pass filter to the transmitter greatly cuts down the interference

A

B-008-001-002
What is one way to tell if radio frequency interference to a receiver is caused by front-end overload?

(c) If the interference is about the same no matter what frequency is used for the transmitter

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3
Q

B-008-001-003
If a neighbour reports television interference whenever you transmit, no matter what band you use, what is probably the cause of the interference?

(a) Incorrect antenna length
(b) Receiver VR tube discharge
(c) Too little transmitter harmonic suppression
(d) Receiver overload

A

B-008-001-003
If a neighbour reports television interference whenever you transmit, no matter what band you use, what is probably the cause of the interference?

(d) Receiver overload

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4
Q

B-008-001-004
What type of filter should be connected to a TV receiver as the first step in trying to prevent RF overload from an amateur HF station transmission?

(a) Low-pass
(b) High-pass
(c) Band-pass
(d) No filter

A

B-008-001-004
What type of filter should be connected to a TV receiver as the first step in trying to prevent RF overload from an amateur HF station transmission?

(b) High-pass

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5
Q

B-008-001-005
During a club ARRL Field Day outing, reception on the 20 m SSB station is compromised every time the 20 m CW station is on the air. What might cause such interference?

(a) Both stations are fed from the same generator
(b) Receiver desensitization
(c) Improper station grounding
(d) Harmonic radiation

A

B-008-001-005
During a club ARRL Field Day outing, reception on the 20 m SSB station is compromised every time the 20 m CW station is on the air. What might cause such interference?

(b) Receiver desensitization

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6
Q

B-008-001-006
Inter-modulation in a broadcast receiver by a nearby transmitter would be noticed in the receiver as:

(a) interference only when a broadcast signal is tuned
(b) the undesired signal in the background of the desired signal
(c) distortion on transmitted voice peaks
(d) interference continuously across the dial

A

B-008-001-006
Inter-modulation in a broadcast receiver by a nearby transmitter would be noticed in the receiver as:

(b) the undesired signal in the background of the desired signal

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7
Q

B-008-001-007
You have connected your hand-held VHF transceiver to an outside gain antenna. You now hear a mixture of signals together with different modulation on your desired frequency. What is the nature of this interference?

(a) Receiver intermodulation interference
(b) Harmonic interference from other stations
(c) Audio stage overload interference
(d) Audio stage intermodulation interference

A

B-008-001-007
You have connected your hand-held VHF transceiver to an outside gain antenna. You now hear a mixture of signals together with different modulation on your desired frequency. What is the nature of this interference?

(a) Receiver intermodulation interference

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8
Q

B-008-001-008
Two or more strong out-of-band signals mix in your receiver to produce interference on a desired frequency. What is this called?

(a) Receiver quieting
(b) Capture effect
(c) Intermodulation interference
(d) Front-end desensitization

A

B-008-001-008
Two or more strong out-of-band signals mix in your receiver to produce interference on a desired frequency. What is this called?

(c) Intermodulation interference

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9
Q

B-008-001-009
Two mobile stations are traveling along the same road in close proximity to each other and having trouble communicating through a local repeater. Why may it be necessary to use simplex operation to communicate between these cars?

(a) Simplex operation does not require the use of CTCSS tones
(b) The strong signal of one mobile transmitter may desensitize the receiver of the other mobile receiver
(c) There is less time delay using simplex operation compared to using a repeater
(d) There are many more simplex frequencies than repeater frequencies available

A

B-008-001-009
Two mobile stations are traveling along the same road in close proximity to each other and having trouble communicating through a local repeater. Why may it be necessary to use simplex operation to communicate between these cars?

(b) The strong signal of one mobile transmitter may desensitize the receiver of the other mobile receiver

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10
Q

B-008-001-010
A television receiver suffers interference on channel 5 (76 - 82 MHz) only when you transmit on 14 MHz. From your home you see the tower of a commercial FM station known to broadcast on 92.5 MHz. Which of these solutions would you try first?

(a) Insert a low pass filter at the antenna connector of the HF transmitter
(b) Insert a high pass filter at the antenna connector of the HF transmitter
(c) Insert a high pass filter at the antenna connector of the television
(d) Insert a low pass filter at the antenna connector of the television

A

B-008-001-010
A television receiver suffers interference on channel 5 (76 - 82 MHz) only when you transmit on 14 MHz. From your home you see the tower of a commercial FM station known to broadcast on 92.5 MHz. Which of these solutions would you try first?

(c) Insert a high pass filter at the antenna connector of the television

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11
Q

B-008-001-011
How can intermodulation be reduced?

(a) By using a better antenna
(b) By increasing the receiver RF gain while decreasing the AF gain
(c) By installing a suitable filter at the receiver
(d) By adjusting the passband tuning

A

B-008-001-011
How can intermodulation be reduced?

(c) By installing a suitable filter at the receiver

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12
Q

B-008-002-001
What devices would you install to reduce or eliminate audio-frequency interference to home entertainment systems?

(a) Coils on ferrite cores
(b) Bypass resistors
(c) Metal-oxide varistors
(d) Bypass inductors

A

B-008-002-001
What devices would you install to reduce or eliminate audio-frequency interference to home entertainment systems?

(a) Coils on ferrite cores

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13
Q

B-008-002-002
What should be done if a properly operating amateur station is the cause of interference to a nearby telephone?

(a) Install a modular plug-in telephone RFI filter close to the telephone device
(b) Ground and shield the local telephone distribution amplifier
(c) Stop transmitting whenever the telephone is in use
(d) Make internal adjustments to the telephone equipment

A

B-008-002-002
What should be done if a properly operating amateur station is the cause of interference to a nearby telephone?

(a) Install a modular plug-in telephone RFI filter close to the telephone device

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14
Q

B-008-002-003
What sound is heard from a public-address system if audio rectification of a nearby single-sideband phone transmission occurs?

(a) Distorted speech from the transmitter’s signals
(b) Clearly audible speech from the transmitter’s signals
(c) On-and-off humming or clicking
(d) A steady hum whenever the transmitter’s carrier is on the air

A

B-008-002-003
What sound is heard from a public-address system if audio rectification of a nearby single-sideband phone transmission occurs?

(a) Distorted speech from the transmitter’s signals

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15
Q

B-008-002-004
What sound is heard from a public-address system if audio rectification of a nearby CW transmission occurs?

(a) On-and-off humming or clicking
(b) Audible, possibly distorted speech
(c) Muffled, severely distorted speech
(d) A steady whistling

A

B-008-002-004
What sound is heard from a public-address system if audio rectification of a nearby CW transmission occurs?

(a) On-and-off humming or clicking

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16
Q

B-008-002-005
How can you minimize the possibility of audio rectification of your transmitter’s signals?

(a) Install bypass capacitors on all power supply rectifiers
(b) Use CW only
(c) Use a solid-state transmitter
(d) Ensure that all station equipment is properly grounded

A

B-008-002-005
How can you minimize the possibility of audio rectification of your transmitter’s signals?

(d) Ensure that all station equipment is properly grounded

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17
Q

B-008-002-006
An amateur transmitter is being heard across the entire dial of a broadcast receiver. The receiver is most probably suffering from:

(a) harmonics interference from the transmitter
(b) poor image rejection
(c) audio rectification in the receiver
(d) splatter from the transmitter

A

B-008-002-006
An amateur transmitter is being heard across the entire dial of a broadcast receiver. The receiver is most probably suffering from:

(c) audio rectification in the receiver

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18
Q

B-008-002-007
Your SSB HF transmissions are heard muffled on a sound system in the living room regardless of its volume setting. What causes this?

(a) Harmonics generated at the transmitter
(b) Audio rectification of strong signals
(c) Improper filtering in the transmitter
(d) Lack of receiver sensitivity and selectivity

A

B-008-002-007
Your SSB HF transmissions are heard muffled on a sound system in the living room regardless of its volume setting. What causes this?

(b) Audio rectification of strong signals

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19
Q

B-008-002-008
What device can be used to minimize the effect of RF pickup by audio wires connected to stereo speakers, intercom amplifiers, telephones, etc.?

(a) Ferrite core
(b) Magnet
(c) Attenuator
(d) Diode

A

B-008-002-008
What device can be used to minimize the effect of RF pickup by audio wires connected to stereo speakers, intercom amplifiers, telephones, etc.?

(a) Ferrite core

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20
Q

B-008-002-009
Stereo speaker leads often act as antennas to pick up RF signals. What is one method you can use to minimize this effect?

(a) Shorten the leads
(b) Lengthen the leads
(c) Connect the speaker through an audio attenuator
(d) Connect a diode across the speaker

A

B-008-002-009
Stereo speaker leads often act as antennas to pick up RF signals. What is one method you can use to minimize this effect?

(a) Shorten the leads

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21
Q

B-008-002-010
One method of preventing RF from entering a stereo set through the speaker leads is to wrap each of the speaker leads:

(a) around a copper bar
(b) around an iron bar
(c) around a wooden dowel
(d) through a ferrite core

A

B-008-002-010
One method of preventing RF from entering a stereo set through the speaker leads is to wrap each of the speaker leads:

(d) through a ferrite core

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22
Q

B-008-002-011
Stereo amplifiers often have long leads which pick up transmitted signals because they act as:

(a) transmitting antennas
(b) RF attenuators
(c) frequency discriminators
(d) receiving antennas

A

B-008-002-011
Stereo amplifiers often have long leads which pick up transmitted signals because they act as:

(d) receiving antennas

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23
Q

B-008-003-001
How can you prevent key-clicks?

(a) By increasing power
(b) By using a better power supply
(c) By using a key-click filter
(d) By sending CW more slowly

A

B-008-003-001
How can you prevent key-clicks?

(c) By using a key-click filter

24
Q

B-008-003-002
If someone tells you that signals from your hand-held transceiver are interfering with other signals on a frequency near yours, what could be the cause?

(a) You need a power amplifier for your hand-held
(b) Your hand-held has a chirp from weak batteries
(c) Your hand-held is transmitting spurious emissions
(d) You need to turn the volume up on your hand-held

A

B-008-003-002
If someone tells you that signals from your hand-held transceiver are interfering with other signals on a frequency near yours, what could be the cause?

(c) Your hand-held is transmitting spurious emissions

25
Q

B-008-003-003
If your transmitter sends signals outside the band where it is transmitting, what is this called?

(a) Side tones
(b) Transmitter chirping
(c) Off-frequency emissions
(d) Spurious emissions

A

B-008-003-003
If your transmitter sends signals outside the band where it is transmitting, what is this called?

(d) Spurious emissions

26
Q

B-008-003-004
What problem may occur if your transmitter is operated without the cover and other shielding in place?

(a) It may transmit a weak signal
(b) It may interfere with other stations operating near its frequency
(c) It may radiate spurious emissions
(d) It may transmit a chirpy signal

A

B-008-003-004
What problem may occur if your transmitter is operated without the cover and other shielding in place?

(c) It may radiate spurious emissions

27
Q

B-008-003-005
In Morse code transmission, local RF interference (key-clicks) is produced by:

(a) frequency shifting caused by poor voltage regulation
(b) the power amplifier, and is caused by high frequency parasitic oscillations
(c) the making and breaking of the circuit at the Morse key
(d) poor waveshaping caused by a poor voltage regulator

A

B-008-003-005
In Morse code transmission, local RF interference (key-clicks) is produced by:

(c) the making and breaking of the circuit at the Morse key

28
Q

B-008-003-006
Key-clicks, heard from a Morse code transmitter at a distant receiver, are the result of:

(a) power supply hum modulating the carrier
(b) sparks emitting RF from the key contacts
(c) changes in oscillator frequency on keying
(d) too sharp rise and decay times of the keyed carrier

A

B-008-003-006
Key-clicks, heard from a Morse code transmitter at a distant receiver, are the result of:

(d) too sharp rise and decay times of the keyed carrier

29
Q

B-008-003-007
In a Morse code transmission, broad bandwidth RF interference (key-clicks) heard at a distance is produced by:

(a) poor shaping of the waveform
(b) shift in frequency when keying the transmitter
(c) sparking at the key contacts
(d) sudden movement in the receiver loudspeaker

A

B-008-003-007
In a Morse code transmission, broad bandwidth RF interference (key-clicks) heard at a distance is produced by:

(a) poor shaping of the waveform

30
Q

B-008-003-008
What should you do if you learn your transmitter is producing key clicks?

(a) Turn the receiver down
(b) Check the keying filter and the functioning of later stages
(c) Regulate the oscillator supply voltage
(d) Use a choke in the RF power output

A

B-008-003-008
What should you do if you learn your transmitter is producing key clicks?

(b) Check the keying filter and the functioning of later stages

31
Q

B-008-003-009
A parasitic oscillation:

(a) is generated by parasitic elements of a Yagi beam
(b) does not cause any radio interference
(c) is an unwanted signal developed in a transmitter
(d) is produced in a transmitter oscillator stage

A

B-008-003-009
A parasitic oscillation:

(c) is an unwanted signal developed in a transmitter

32
Q

B-008-003-010
Parasitic oscillations in the RF power amplifier stage of a transmitter may be found:

(a) on harmonic frequencies
(b) at high or low frequencies
(c) at high frequencies only
(d) at low frequencies only

A

B-008-003-010
Parasitic oscillations in the RF power amplifier stage of a transmitter may be found:

(b) at high or low frequencies

33
Q

B-008-003-011
Transmitter RF amplifiers can generate parasitic oscillations:

(a) on VHF frequencies only
(b) above or below the transmitter frequency
(c) on the transmitter fundamental frequency
(d) on harmonics of the transmitter frequency

A

B-008-003-011
Transmitter RF amplifiers can generate parasitic oscillations:

(b) above or below the transmitter frequency

34
Q

B-008-004-001
If a neighbour reports television interference on one or two channels only when you transmit on 15 metres, what is probably the cause of the interference?

(a) De ionization of the ionosphere near your neighbour’s TV antenna
(b) TV receiver front-end overload
(c) Too much low pass filtering on the transmitter
(d) Harmonic radiation from your transmitter

A

B-008-004-001
If a neighbour reports television interference on one or two channels only when you transmit on 15 metres, what is probably the cause of the interference?

(d) Harmonic radiation from your transmitter

35
Q

B-008-004-002
What is meant by harmonic radiation?

(a) Unwanted signals that are combined with a 60-Hz hum
(b) Unwanted signals caused by sympathetic vibrations from a nearby transmitter
(c) Unwanted signals at frequencies which are multiples of the fundamental (chosen) frequency
(d) Signals which cause skip propagation to occur

A

B-008-004-002
What is meant by harmonic radiation?

(c) Unwanted signals at frequencies which are multiples of the fundamental (chosen) frequency

36
Q

B-008-004-003
Why is harmonic radiation from an amateur station not wanted?

(a) It uses large amounts of electric power
(b) It may cause sympathetic vibrations in nearby transmitters
(c) It may cause interference to other stations and may result in out-of-band signals
(d) It may cause auroras in the air

A

B-008-004-003
Why is harmonic radiation from an amateur station not wanted?

(c) It may cause interference to other stations and may result in out-of-band signals

37
Q

B-008-004-004
What type of interference may come from a multi-band antenna connected to a poorly tuned transmitter?

(a) Harmonic radiation
(b) Parasitic excitation
(c) Intermodulation
(d) Auroral distortion

A

B-008-004-004
What type of interference may come from a multi-band antenna connected to a poorly tuned transmitter?

(a) Harmonic radiation

38
Q

B-008-004-005
If you are told your station was heard on 21 375 kHz, but at the time you were operating on 7125 kHz, what is one reason this could happen?

(a) Your transmitter was radiating harmonic signals
(b) Your transmitter’s power-supply filter choke was bad
(c) You were sending CW too fast
(d) Your transmitter’s power-supply filter capacitor was bad

A

B-008-004-005
If you are told your station was heard on 21 375 kHz, but at the time you were operating on 7125 kHz, what is one reason this could happen?

(a) Your transmitter was radiating harmonic signals

39
Q

B-008-004-006
What causes splatter interference?

(a) Keying a transmitter too fast
(b) Signals from a transmitter’s output circuit are being sent back to its input circuit
(c) The transmitting antenna is the wrong length
(d) Overmodulating a transmitter

A

B-008-004-006
What causes splatter interference?

(d) Overmodulating a transmitter

40
Q

B-008-004-007
Your amateur radio transmitter appears to be creating interference to the television on channel 3 (60-66 MHz) when you are transmitting on the 15 metre band. Other channels are not affected. The most likely cause is:

(a) no high-pass filter on the TV
(b) a bad ground at the transmitter
(c) harmonic radiation from the transmitter
(d) front-end overload of the TV

A

B-008-004-007
Your amateur radio transmitter appears to be creating interference to the television on channel 3 (60-66 MHz) when you are transmitting on the 15 metre band. Other channels are not affected. The most likely cause is:

(c) harmonic radiation from the transmitter

41
Q

B-008-004-008
One possible cause of TV interference by harmonics from an SSB transmitter is from “flat topping” - driving the power amplifier into non-linear operation. The most appropriate remedy for this is:

(a) retune transmitter output
(b) reduce microphone gain
(c) use another antenna
(d) reduce oscillator output

A

B-008-004-008
One possible cause of TV interference by harmonics from an SSB transmitter is from “flat topping” - driving the power amplifier into non-linear operation. The most appropriate remedy for this is:

(b) reduce microphone gain

42
Q

B-008-004-009
In a transmitter, excessive harmonics are produced by:

(a) low SWR
(b) resonant circuits
(c) overdriven stages
(d) a linear amplifier

A

B-008-004-009
In a transmitter, excessive harmonics are produced by:

(c) overdriven stages

43
Q

B-008-004-010
An interfering signal from a transmitter is found to have a frequency of 57 MHz (TV Channel 2 is 54 - 60 MHz). This signal could be the:

(a) crystal oscillator operating on its fundamental
(b) seventh harmonic of an 80 metre transmission
(c) third harmonic of a 15 metre transmission
(d) second harmonic of a 10 metre transmission

A

B-008-004-010
An interfering signal from a transmitter is found to have a frequency of 57 MHz (TV Channel 2 is 54 - 60 MHz). This signal could be the:

(d) second harmonic of a 10 metre transmission

44
Q

B-008-004-011
Harmonics may be produced in the RF power amplifier of a transmitter if:

(a) the output tank circuit is tuned to the fundamental frequency
(b) the oscillator frequency is unstable
(c) modulation is applied to a high-level stage
(d) excessive drive signal is applied to it

A

B-008-004-011
Harmonics may be produced in the RF power amplifier of a transmitter if:

(d) excessive drive signal is applied to it

45
Q

B-008-005-001
What type of filter might be connected to an amateur HF transmitter to cut down on harmonic radiation?

(a) A key-click filter
(b) A low pass filter
(c) A high pass filter
(d) A CW filter

A

B-008-005-001
What type of filter might be connected to an amateur HF transmitter to cut down on harmonic radiation?

(b) A low pass filter

46
Q

B-008-005-002
Why do modern HF transmitters have a built-in low pass filter in their RF output circuits?

(a) To reduce fundamental radiation
(b) To reduce harmonic radiation
(c) To reduce low frequency interference to other amateurs
(d) To reduce RF energy below a cut-off point

A

B-008-005-002
Why do modern HF transmitters have a built-in low pass filter in their RF output circuits?

(b) To reduce harmonic radiation

47
Q

B-008-005-003
What circuit blocks RF energy above and below a certain limit?

(a) A high pass filter
(b) A band pass filter
(c) An input filter
(d) A low pass filter

A

B-008-005-003
What circuit blocks RF energy above and below a certain limit?

(b) A band pass filter

48
Q

B-008-005-004
What should be the impedance of a low pass filter as compared to the impedance of the transmission line into which it is inserted?

(a) About the same
(b) Substantially lower
(c) Twice the transmission line impedance
(d) Substantially higher

A

B-008-005-004
What should be the impedance of a low pass filter as compared to the impedance of the transmission line into which it is inserted?

(a) About the same

49
Q

B-008-005-005
In order to reduce the harmonic output of a high frequency (HF) transmitter, which of the following filters should be installed at the transmitter?

(a) Low pass
(b) Key click
(c) High pass
(d) Rejection

A

B-008-005-005
In order to reduce the harmonic output of a high frequency (HF) transmitter, which of the following filters should be installed at the transmitter?

(a) Low pass

50
Q

B-008-005-006
To reduce harmonic output from a high frequency transmitter, you would put a ____________ in the transmission line as close to the transmitter as possible.

(a) high pass filter
(b) low pass filter
(c) band reject filter
(d) wave trap

A

B-008-005-006
To reduce harmonic output from a high frequency transmitter, you would put a ____________ in the transmission line as close to the transmitter as possible.

(b) low pass filter

51
Q

B-008-005-007
To reduce energy from an HF transmitter getting into a television set, you would place a ____________ as close to the TV as possible.

(a) low pass filter
(b) wave trap
(c) band reject filter
(d) high pass filter

A

B-008-005-007
To reduce energy from an HF transmitter getting into a television set, you would place a ____________ as close to the TV as possible.

(d) high pass filter

52
Q

B-008-005-008
A band pass filter will:

(a) allow only certain frequencies through
(b) attenuate high frequencies but not low
(c) pass frequencies each side of a band
(d) stop frequencies in a certain band

A

B-008-005-008
A band pass filter will:

(a) allow only certain frequencies through

53
Q

B-008-005-009
A band reject filter will:

(a) allow only two frequencies through
(b) pass frequencies below 100 MHz
(c) pass frequencies each side of a band
(d) stop frequencies each side of a band

A

B-008-005-009
A band reject filter will:

(c) pass frequencies each side of a band

54
Q

B-008-005-010
A high pass filter would normally be fitted:

(a) between microphone and speech amplifier
(b) at the Morse key or keying relay in a transmitter
(c) between transmitter output and transmission line
(d) at the antenna terminals of the TV receiver

A

B-008-005-010
A high pass filter would normally be fitted:

(d) at the antenna terminals of the TV receiver

55
Q

B-008-005-011
A low pass filter suitable for a high frequency transmitter would:

(a) pass audio frequencies above 3 kHz
(b) attenuate frequencies above 30 MHz
(c) attenuate frequencies below 30 MHz
(d) pass audio frequencies below 3 kHz

A

B-008-005-011
A low pass filter suitable for a high frequency transmitter would:

(b) attenuate frequencies above 30 MHz

ISED - BASIC Radio Amateur (8 decks)

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