E4A01
How does a spectrum analyzer differ from a conventional oscilloscope?
A. A spectrum analyzer measures ionospheric reflection; an oscilloscope displays electrical signals
B. A spectrum analyzer displays the peak amplitude of signals; an oscilloscope displays the average amplitude of signals
C. A spectrum analyzer displays signals in the frequency domain; an oscilloscope displays signals in the time domain
D. A spectrum analyzer displays radio frequencies; an oscilloscope displays audio frequencies
E4A02
Which of the following parameters would a typical spectrum analyzer display on the horizontal axis?
A. SWR
B. Q
C. Time
D. Frequency
E4A03
Which of the following parameters would a typical spectrum analyzer display on the vertical axis?
A. Amplitude
B. Duration
C. SWR
D. Q
E4A04
Which of the following test instruments is used to display spurious signals from a radio transmitter?
A. A spectrum analyzer
B. A wattmeter
C. A logic analyzer
D. A time-domain reflectometer
E4A05
Which of the following test instruments is used to display intermodulation distortion products in an SSB transmission?
A. A wattmeter
B. A spectrum analyzer
C. A logic analyzer
D. A time-domain reflectometer
E4A06
Which of the following could be determined with a spectrum analyzer?
A. The degree of isolation between the input and output ports of a 2 meter duplexer
B. Whether a crystal is operating on its fundamental or overtone frequency
C. The spectral output of a transmitter
D. All of these choices are correct
E4A07
Which of the following is an advantage of using an antenna analyzer vs. a SWR bridge to measure antenna SWR?
A. Antenna analyzers automatically tune your antenna for resonance
B. Antenna analyzers typically do not need an external RF source
C. Antenna analyzers typically display a time-varying representation of the modulation envelope
D. All of these answers are correct
E4A08
Which of the following instruments would be best for measuring the SWR of a beam antenna?
A. A spectrum analyzer
B. A Q meter
C. An ohmmeter
D. An antenna analyzer
E4A09 (
Which of the following is most important when adjusting PSK31 transmitting levels?
A. Power output
B. PA current
C. ALC level
D. SWR
E4A10
Which of the following is a useful test for a functioning NPN transistor in an active circuit where the transistor should be biased "on" ?
A. Measure base-to-emitter resistance with an ohmmeter; it should be approximately 6 to 7 ohms
B. Measure base-to-emitter resistance with an ohmmeter; it should be approximately 0.6 to 0.7 ohms
C. Measure base-to-emitter voltage with a voltmeter; it should be approximately 6 to 7 volts
D. Measure base-to-emitter voltage with a voltmeter; it should be approximately 0.6 to 0.7 volts
E4A11
Which of the following test instruments can be used to indicate pulse conditions in a digital logic circuit?
A. A logic probe
B. An ohmmeter
C. An electroscope
D. A Wheatstone bridge
E4A12
Which of the following procedures is an important precaution to follow when connecting a spectrum analyzer to a transmitter output?
A. Use high quality double shielded coaxial cables to reduce signal losses
B. Attenuate the transmitter output going to the spectrum analyzer
C. Match the antenna to the load
D. All of these choices are correct
Which of the following is a characteristic of a good harmonic frequency marker?
A. Wide tuning range
B. Frequency stability
C. Linear output amplifier
D. All of the above
E4B02
Which of the following factors most affects the accuracy of a frequency counter?
A. Input attenuator accuracy
B. Time base accuracy
C. Decade divider accuracy
D. Temperature coefficient of the logic
E4B03
What is an advantage of using a bridge circuit to measure impedance?
A. It provides an excellent match under all conditions
B. It is relatively immune to drift in the signal generator source
C. The measurement is based on obtaining a null in voltage, which can be done very precisely
D. It can display results directly in Smith chart format
E4B04
If a frequency counter with a specified accuracy of +/- 1.0 ppm reads 146,520,000 Hz, what is the most the actual frequency being measured could differ from the reading?
A. 165.2 Hz
B. 14.652 kHz
C. 146.52 Hz
D. 1.4652 MHz
E4B05
If a frequency counter with a specified accuracy of +/- 0.1 ppm reads 146,520,000 Hz, what is the most the actual frequency being measured could differ from the reading?
A. 14.652 Hz
B. 0.1 MHz
C. 1.4652 Hz
D. 1.4652 kHz
E4B06
If a frequency counter with a specified accuracy of +/- 10 ppm reads 146,520,000 Hz, what is the most the actual frequency being measured could differ from the reading?
A. 146.52 Hz
B. 10 Hz
C. 146.52 kHz
D. 1465.20 Hz
E4B07
How much power is being absorbed by the load when a directional power meter connected between a transmitter and a terminating load reads 100 watts forward power and 25 watts reflected power?
A. 100 watts
B. 125 watts
C. 25 watts
D. 75 watts
E4B08
Which of the following is good practice when using an oscilloscope probe?
A. Keep the ground connection of the probe as short as possible
B. Never use a high impedance probe to measure a low impedance circuit
C. Never use a DC-coupled probe to measure an AC circuit
D. All of these choices are correct
E4B09
Which of the following is a characteristic of a good DC voltmeter?
A. High reluctance input
B. Low reluctance input
C. High impedance input
D. Low impedance input
E4B10
What is indicated if the current reading on an RF ammeter placed in series with the antenna feedline of a transmitter increases as the transmitter is tuned to resonance?
A. There is possibly a short to ground in the feedline
B. The transmitter is not properly neutralized
C. There is an impedance mismatch between the antenna and feedline
D. There is more power going into the antenna
E4B11
Which of the following describes a method to measure intermodulation distortion in an SSB transmitter?
A. Modulate the transmitter with two non-harmonically related radio frequencies and observe the RF output with a spectrum analyzer
B. Modulate the transmitter with two non-harmonically related audio frequencies and observe the RF output with a spectrum analyzer
C. Modulate the transmitter with two harmonically related audio frequencies and observe the RF output with a peak reading wattmeter
D. Modulate the transmitter with two harmonically related audio frequencies and observe the RF output with a logic analyzer
E4B12
How should a portable SWR analyzer be connected when measuring antenna resonance and feedpoint impedance?
A. Loosely couple the analyzer near the antenna base
B. Connect the analyzer via a high-impedance transformer to the antenna
C. Connect the antenna and a dummy load to the analyzer
D. Connect the antenna feed line directly to the analyzer's connector
E4B13
What is the significance of voltmeter sensitivity expressed in ohms per volt?
A. The full scale reading of the voltmeter multiplied by its ohms per volt rating will provide the input impedance of the voltmeter
B. When used as a galvanometer, the reading in volts multiplied by the ohms/volt will determine the power drawn by the device under test
C. When used as an ohmmeter, the reading in ohms divided by the ohms/volt will determine the voltage applied to the circuit
D. When used as an ammeter, the full scale reading in amps divided by ohms/volt will determine the size of shunt needed
E4B14
How is the compensation of an oscilloscope probe typically adjusted?
A. A square wave is observed and the probe is adjusted until the horizontal portions of the displayed wave is as nearly flat as possible
B. A high frequency sine wave is observed, and the probe is adjusted for maximum amplitude
C. A frequency standard is observed, and the probe is adjusted until the deflection time is accurate
D. A DC voltage standard is observed, and the probe is adjusted until the displayed voltage is accurate
E4B15
What happens if a dip-meter is too tightly coupled to a tuned circuit being checked?
A. Harmonics are generated
B. A less accurate reading results
C. Cross modulation occurs
D. Intermodulation distortion occurs
E4B16
Which of these factors limits the accuracy of a D'Arsonval-type meter?
A. Its magnetic flux density
B. Coil impedance
C. Deflection rate
D. Electromagnet current
E4B17
Which of the following can be used as a relative measurement of the Q for a series-tuned circuit?
A. The inductance to capacitance ratio
B. The frequency shift
C. The bandwidth of the circuit's frequency response
D. The resonant frequency of the circuit
What is the effect of excessive phase noise in the local oscillator section of a receiver?
A. It limits the receiver ability to receive strong signals
B. It reduces the receiver sensitivity
C. It decreases the receiver third-order intermodulation distortion dynamic range
D. It can cause strong signals on nearby frequencies to interfere with reception of weak signals
E4C02
Which of the following is the result of the capture effect in an FM receiver?
A. All signals on a frequency are demodulated
B. None of the signals could be heard
C. The strongest signal received is the only demodulated signal
D. The weakest signal received is the only demodulated signal
E4C03
What is the term for the blocking of one FM phone signal by another, stronger FM phone signal?
A. Desensitization
B. Cross-modulation interference
C. Capture effect
D. Frequency discrimination
E4C04
What is meant by the noise floor of a receiver?
A. The minimum level of noise at the audio output when the RF gain is turned all the way down
B. The equivalent phase noise power generated by the local oscillator
C. The minimum level of noise that will overload the RF amplifier stage
D. The equivalent input noise power when the antenna is replaced with a matched dummy load
E4C05
What does a value of -174 dBm/Hz represent with regard to the noise floor of a receiver?
A. The minimum detectable signal as a function of receive frequency
B. The theoretical noise at the input of a perfect receiver at room temperature
C. The noise figure of a 1 Hz bandwidth receiver
D. The galactic noise contribution to minimum detectable signal
E4C06
The thermal noise value of a receiver is -174 dBm/Hz. What is the theoretically best minimum detectable signal for a 400 Hz bandwidth receiver?
A. 174 dBm
B. -164 dBm
C. -155 dBm
D. -148 dBm
E4C07
What does the MDS of a receiver represent?
A. The meter display sensitivity
B. The minimum discernible signal
C. The multiplex distortion stability
D. The maximum detectable spectrum
E4C08
How might lowering the noise figure affect receiver performance?
A. It would reduce the signal to noise ratio
B. It would increase signal to noise ratio
C. It would reduce bandwidth
D. It would increase bandwidth
E4C09
Which of the following is most likely to be the limiting condition for sensitivity in a modern communications receiver operating at 14 MHz?
A. The noise figure of the RF amplifier
B. Mixer noise
C. Conversion noise
D. Atmospheric noise
E4C10
Which of the following is a desirable amount of selectivity for an amateur RTTY HF receiver?
A. 100 Hz
B. 300 Hz
C. 6000 Hz
D. 2400 Hz
E4C11
Which of the following is a desirable amount of selectivity for an amateur single-sideband phone receiver?
A. 1 kHz
B. 2.4 kHz
C. 4.2 kHz
D. 4.8 kHz
E4C12
What is an undesirable effect of using too wide a filter bandwidth in the IF section of a receiver?
A. Output-offset overshoot
B. Filter ringing
C. Thermal-noise distortion
D. Undesired signals may be heard
E4C13
How does a narrow band roofing filter affect receiver performance?
A. It improves sensitivity by reducing front end noise
B. It improves intelligibility by using low Q circuitry to reduce ringing
C. It improves dynamic range by keeping strong signals near the receive frequency out of the IF stages
D. All of these choice are correct
E4C14
Which of these choices is a desirable amount of selectivity for an amateur VHF FM receiver?
A. 1 kHz
B. 2.4 kHz
C. 4.2 kHz
D. 15 kHz
E4C15
What is the primary source of noise that can be heard from an HF-band receiver with an antenna connected?
A. Detector noise
B. Induction motor noise
C. Receiver front-end noise
D. Atmospheric noise
What is meant by the blocking dynamic range of a receiver?
A. The difference in dB between the level of an incoming signal which will cause 1 dB of gain compression, and the level of the noise floor
B. The minimum difference in dB between the levels of two FM signals which will cause one signal to block the other
C. The difference in dB between the noise floor and the third order intercept point
D. The minimum difference in dB between two signals which produce third order intermodulation products greater than the noise floor
E4D02
Which of the following describes two types of problems caused by poor dynamic range in a communications receiver?
A. Cross modulation of the desired signal and desensitization from strong adjacent signals
B. Oscillator instability requiring frequent retuning, and loss of ability to recover the opposite sideband, should it be transmitted
C. Cross modulation of the desired signal and insufficient audio power to operate the speaker
D. Oscillator instability and severe audio distortion of all but the strongest received signals
E4D03
How can intermodulation interference between two repeaters occur?
A. When the repeaters are in close proximity and the signals cause feedback in one or both transmitter final amplifiers
B. When the repeaters are in close proximity and the signals mix in one or both transmitter final amplifiers
C. When the signals from the transmitters are reflected out of phase from airplanes passing overhead
D. When the signals from the transmitters are reflected in phase from airplanes passing overhead
E4D04
What is an effective way to reduce or eliminate intermodulation interference between two repeater transmitters operating in close proximity to one another?
A. By installing a band-pass filter in the feed line between the transmitter and receiver
B. By installing a properly terminated circulator at the output of the transmitter
C. By using a Class C final amplifier
D. By using a Class D final amplifier
E4D05
If a receiver tuned to 146.70 MHz receives an intermodulation-product signal whenever a nearby transmitter transmits on 146.52 MHz, what are the two most likely frequencies for the other interfering signal?
A. 146.34 MHz and 146.61 MHz
B. 146.88 MHz and 146.34 MHz
C. 146.10 MHz and 147.30 MHz
D. 73.35 MHz and 239.40 MHz
E4D06
If the signals of two transmitters mix together in one or both of their final amplifiers, and unwanted signals at the sum and difference frequencies of the original signals are generated, what is this called?
A. Amplifier desensitization
B. Neutralization
C. Adjacent channel interference
D. Intermodulation interference
E4D07
Which of the following describes the most significant effect of an off-frequency signal when it is causing cross-modulation interference to a desired signal?
A. A large increase in background noise
B. A reduction in apparent signal strength
C. The desired signal can no longer be heard
D. The off-frequency unwanted signal is heard in addition to the desired signal
E4D08
What causes intermodulation in an electronic circuit?
A. Too little gain
B. Lack of neutralization
C. Nonlinear circuits or devices
D. Positive feedback
E4D09
What is the purpose of the preselector in a communications receiver?
A. To store often-used frequencies
B. To provide a range of AGC time constants
C. To improve rejection of unwanted signals
D. To allow selection of the optimum RF amplifier device
E4D10
What does a third-order intercept level of 40 dBm mean with respect to receiver performance?
A. Signals less than 40 dBm will not generate audible third-order intermodulation products
B. The receiver can tolerate signals up to 40 dB above the noise floor without producing third-order intermodulation products
C. A pair of 40 dBm signals will theoretically generate the same output on the third order intermodulation frequency as on the input frequency
D. A pair of 1 mW input signals will produce a third-order intermodulation product which is 40 dB stronger than the input signal
E4D11
Why are third-order intermodulation products within a receiver of particular interest compared to other products?
A. The third-order product of two signals which are in the band is itself likely to be within the band
B. The third-order intercept is much higher than other orders
C. Third-order products are an indication of poor image rejection
D. Third-order intermodulation produces three products for every input signal
E4D12
What is the term for the reduction in receiver sensitivity caused by a strong signal near the received frequency?
A. Desensitization
B. Quieting
C. Cross-modulation interference
D. Squelch gain rollback
E4D13
Which of the following can cause receiver desensitization?
A. Audio gain adjusted too low
B. Strong adjacent-channel signals
C. Audio bias adjusted too high
D. Squelch gain adjusted too low
E4D14
Which of the following is a way to reduce the likelihood of receiver desensitization?
A. Decrease the RF bandwidth of the receiver
B. Raise the receiver IF frequency
C. Increase the receiver front end gain
D. Switch from fast AGC to slow AGC
Which of the following types of receiver noise can often be reduced by use of a receiver noise blanker?
A. Ignition Noise
B. Broadband “white” noise
C. Heterodyne interference
D. All of these choices are correct
E4E02
Which of the following types of receiver noise can often be reduced with a DSP noise filter?
A. Broadband “white” noise
B. Ignition noise
C. Power line noise
D. All of these choices are correct
E4E03
Which of the following signals might a receiver noise blanker be able to remove from desired signals?
A. Signals which are constant at all IF levels
B. Signals which appear correlated across a wide bandwidth
C. Signals which appear at one IF but not another
D. Signals which have a sharply peaked frequency distribution
E4E04
How can conducted and radiated noise caused by an automobile alternator be suppressed?
A. By installing filter capacitors in series with the DC power lead and by installing a blocking capacitor in the field lead
B. By connecting the radio to the battery by the longest possible path and installing a blocking capacitor in both leads
C. By installing a high-pass filter in series with the radio's power lead and a low-pass filter in parallel with the field lead
D. By connecting the radio's power leads directly to the battery and by installing coaxial capacitors in line with the alternator leads
E4E05
How can noise from an electric motor be suppressed?
A. By installing a ferrite bead on the AC line used to power the motor
B. By installing a brute-force AC-line filter in series with the motor leads
C. By installing a bypass capacitor in series with the motor leads
D. By using a ground-fault current interrupter in the circuit used to power the motor
E4E06
What is a major cause of atmospheric static?
A. Solar radio frequency emissions
B. Thunderstorms
C. Geomagnetic storms
D. Meteor showers
E4E07
How can you determine if line-noise interference is being generated within your home?
A. By checking the power-line voltage with a time-domain reflectometer
B. By observing the AC power line waveform with an oscilloscope
C. By turning off the AC power line main circuit breaker and listening on a battery-operated radio
D. By observing the AC power line voltage with a spectrum analyzer
E4E08
What type of signal is picked up by electrical wiring near a radio transmitter?
A. A common-mode signal at the frequency of the radio transmitter
B. An electrical-sparking signal
C. A differential-mode signal at the AC power line frequency
D. Harmonics of the AC power line frequency
E4E09
What undesirable effect can occur when using an IF type noise blanker?
A. Received audio in the speech range might have an echo effect
B. The audio frequency bandwidth of the received signal might be compressed
C. Nearby signals may appear to be excessively wide even if they meet emission standards
D. FM signals can no longer be demodulated
E4E10
What is a common characteristic of interference caused by a "touch controlled" electrical device?
A. The interfering signal sounds like AC hum on an AM receiver or a carrier modulated by 60 Hz FM on a SSB or CW receiver
B. The interfering signal may drift slowly across the HF spectrum
C. The interfering signal can be several kHz in width and usually repeats at regular intervals across a HF band
D. All of these answers are correct
E4E11
What is the most likely cause if you are hearing combinations of local AM broadcast signals inside one or more of the MF or HF ham bands?
A. The broadcast station is transmitting an over-modulated signal
B. Nearby corroded metal joints are mixing and re-radiating the BC signals
C. You are receiving sky-wave signals from a distant station
D. Your station receiver IF amplifier stage is defective
E4E12
What is one disadvantage of using some automatic DSP notch-filters when attempting to copy CW signals?
A. The DSP filter can remove the desired signal at the same time as it removes interfering signals
B. Any nearby signal passing through the DSP system will always overwhelm the desired signal
C. Received CW signals will appear to be modulated at the DSP clock frequency
D. Ringing in the DSP filter will completely remove the spaces between the CW characters
E4E13
What might be the cause of a loud "roaring" or "buzzing" AC line type of interference that comes and goes at intervals?
A. Arcing contacts in a thermostatically controlled device
B. A defective doorbell or doorbell transformer inside a nearby residence
C. A malfunctioning illuminated advertising display
D. All of these answers are correct
E4E14
What is one type of electrical interference that might be caused by the operation of a nearby personal computer?
A. A loud AC hum in the audio output of your station receiver
B. A clicking noise at intervals of a few seconds
C. The appearance of unstable modulated or unmodulated signals at specific frequencies
D. A whining type noise that continually pulses off and on