/50 Extra Class (2024-2028) Online practice test for the U.S. ham radio extra license exam. 1 / 50 Under what circumstances may a dealer sell an external RF power amplifier capable of operation below 144 MHz if it has not been granted FCC certification? The equipment dealer assembled it from a kit It was manufactured and certificated in a country which has a reciprocal certification agreement with the FCC Gain is less than 23 dB when driven by power of 10 watts or less It was purchased in used condition from an amateur operator and is sold to another amateur operator for use at that operator's station 2 / 50 What is the effect of aliasing on a digital oscilloscope when displaying a waveform? The waveform DC offset will be inaccurate Calibration of the vertical scale is no longer valid A false, jittery low-frequency version of the waveform is displayed Excessive blanking occurs, which prevents display of the waveform 3 / 50 How much does the gain of an ideal parabolic reflector antenna increase when the operating frequency is doubled? 4 dB 2 dB 6 dB 3 dB 4 / 50 For what portion of the signal cycle does each active element in a push-pull, Class AB amplifier conduct? More than 180 degrees but less than 360 degrees Less than 180 degrees Exactly 180 degrees The entire cycle 5 / 50 Which of the following can create intermittent loud roaring or buzzing AC line interference? A malfunctioning illuminated advertising display Arcing contacts in a thermostatically controlled device A defective doorbell or doorbell transformer inside a nearby residence All these choices are correct 6 / 50 At what time of year is sporadic-E propagation most likely to occur? Around the solstices, especially the winter solstice Around the equinoxes, especially the fall equinox Around the equinoxes, especially the spring equinox Around the solstices, especially the summer solstice 7 / 50 What is the relationship between symbol rate and baud? Baud is twice the symbol rate They are the same The relationship depends on the specific code used Baud rate is half the symbol rate 8 / 50 What is the purpose of digital store-and-forward functions on an amateur radio satellite? To hold digital messages in the satellite for later download To relay messages between satellites To upload operational software for the transponder To delay download of telemetry between satellites 9 / 50 What is the name given to an impurity atom that adds holes to a semiconductor crystal structure? Acceptor impurity Donor impurity Insulator impurity N-type impurity 10 / 50 What technique shows that a square wave is made up of a sine wave and its odd harmonics? Differential analysis Vector analysis Numerical analysis Fourier analysis 11 / 50 When using rectangular coordinates to graph the impedance of a circuit, what do the axes represent? The X axis represents the resistive component, and the Y axis represents the reactive component The X axis represents the magnitude, and the Y axis represents the phase angle The X axis represents the phase angle, and the Y axis represents the magnitude The X axis represents the reactive component, and the Y axis represents the resistive component 12 / 50 What is the function of a loading coil in an electrically short antenna? To resonate the antenna by cancelling the capacitive reactance To increase the SWR bandwidth by increasing net reactance To lower the Q To lower the losses 13 / 50 What combines to create the self-resonance of a component? The component's nominal and parasitic reactance The component's resistance and reactance The component's inductance and capacitance The component's electrical length and impedance 14 / 50 What is the typical output impedance of an op-amp? 10,000 ohms Very low 100 ohms Very high 15 / 50 What sets the minimum detectable signal level for a direct-sampling software defined receiver in the absence of atmospheric or thermal noise? Reference voltage level and sample width in bits Sample clock phase noise Data storage transfer rate Missing codes and jitter 16 / 50 What aspect of receiver analog-to-digital conversion determines the maximum receive bandwidth of a direct-sampling software defined radio (SDR)? Sample rate Integral non-linearity Differential non-linearity Sample width in bits 17 / 50 What does a third-order intercept level of 40 dBm mean with respect to receiver performance? The receiver can tolerate signals up to 40 dB above the noise floor without producing third-order intermodulation products Signals less than 40 dBm will not generate audible third-order intermodulation products A pair of 40 dBm input signals will theoretically generate a third-order intermodulation product that has the same output amplitude as either of the input signals A pair of 1 mW input signals will produce a third-order intermodulation product that is 40 dB stronger than the input signal 18 / 50 Which circuit is bistable? An AND gate An OR gate A flip-flop A bipolar amplifier 19 / 50 What is the phase relationship between the current through and the voltage across a series resonant circuit at resonance? The current leads the voltage by 90 degrees The voltage leads the current by 90 degrees The voltage and current are in phase The voltage and current are 180 degrees out of phase 20 / 50 What is the front-to-back ratio of the antenna radiation pattern shown in Figure E9-1? 24 dB 36 dB 14 dB 18 dB 21 / 50 What is the bandwidth of a 4,800-Hz frequency shift, 9,600-baud ASCII FM transmission? 15.36 kHz 9.6 kHz 5.76 kHz 4.8 kHz 22 / 50 In Figure E7-1, what is the purpose of R1 and R2? Feedback Voltage divider bias Self bias Load resistors 23 / 50 What is the most common method of reducing key clicks? Insert low-pass filters at the transmitter output Reduce keying waveform rise and fall times Insert high-pass filters at the transmitter output Increase keying waveform rise and fall times 24 / 50 What type of equipment is commonly used to implement an amateur radio mesh network? A computer running EchoLink to provide interface from the radio to the internet A wireless router running custom firmware A 440 MHz transceiver with a 9,600-baud modem A 2-meter VHF transceiver with a 1,200-baud modem 25 / 50 Why is a switching type power supply less expensive and lighter than an equivalent linear power supply? The high frequency inverter design uses much smaller transformers and filter components for an equivalent power output The control circuitry uses less current, therefore smaller heat sinks are required It recovers power from the unused portion of the AC cycle, thus using fewer components The inverter design does not require an output filter circuit 26 / 50 What is the Cabrillo format? A digital protocol specifically designed for rapid contest exchanges A standard for submission of electronic contest logs The most common set of contest rules A method of exchanging information during a contest QSO 27 / 50 What type of circuit is shown in Figure E7-2? Linear voltage regulator Switching voltage regulator Common emitter amplifier Common base amplifier 28 / 50 What characteristic of a PIN diode makes it useful as an RF switch? Reverse bias controls its forward voltage drop Extremely high reverse breakdown voltage Ability to dissipate large amounts of power Low junction capacitance 29 / 50 Which S parameter is equivalent to forward gain? S21 S12 S11 S22 30 / 50 What type of radiation pattern is created by two 1/4-wavelength vertical antennas spaced 1/2-wavelength apart and fed in phase? A figure-eight end-fire along the axis of the array Cardioid Omni-directional A figure-eight broadside to the axis of the array 31 / 50 How can data rate be increased without increasing bandwidth? Using forward error correction It is impossible Using a more efficient digital code Increasing analog-to-digital conversion resolution 32 / 50 How can two linearly polarized Yagi antennas be used to produce circular polarization? Stack two Yagis to form an array with the respective elements in parallel planes fed in phase Arrange two Yagis collinear to each other with the driven elements fed 180 degrees out of phase Arrange two Yagis on the same axis and perpendicular to each other with the driven elements at the same point on the boom and fed 90 degrees out of phase Stack two Yagis to form an array with the respective elements in parallel planes fed 90 degrees out of phase 33 / 50 What does the value of Bz (B sub z) represent? Duration of long-delayed echoes Geomagnetic field stability North-south strength of the interplanetary magnetic field Critical frequency for vertical transmissions 34 / 50 What property of an LED's semiconductor material determines its forward voltage drop? Intrinsic resistance Junction capacitance Junction depth Band gap 35 / 50 What type of data is reported by amateur radio propagation reporting networks? Magnetic declination Electric field intensity Solar flux Digital-mode and CW signals 36 / 50 Which method generates an SSB signal using digital signal processing? Varying quartz crystal characteristics are emulated in digital form Mixing products are converted to voltages and subtracted by adder circuits A frequency synthesizer removes unwanted sidebands Signals are combined in quadrature phase relationship 37 / 50 Which characteristic of a Schottky diode makes it a better choice than a silicon junction diode for use as a power supply rectifier? Longer carrier retention time More constant reverse avalanche voltage Much higher reverse voltage breakdown Lower forward voltage drop 38 / 50 What logical operation does an OR gate perform? It produces a 0 at its output if all inputs are 1 It produces a 0 at its output if some but not all inputs are 1 It produces a 1 at its output if any input is 1 It produces a 1 at its output if all inputs are 0 39 / 50 What antenna matching system matches coaxial cable to an antenna by connecting the shield to the center of the antenna and the conductor a fraction of a wavelength to one side? Stub match Gamma match Delta match T-match 40 / 50 What is an effect of increasing Q in a series resonant circuit? Internal voltages increase Phase shift can become uncontrolled Fewer components are needed for the same performance Parasitic effects are minimized 41 / 50 What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by EME? 2,000 miles, if the moon is at apogee 5,000 miles, if the moon is at perigee 12,000 miles, if the moon is “visible†by both stations 2,000 miles, if the moon is at perigee 42 / 50 Which of the following component package types have the least parasitic effects at frequencies above the HF range? Axial lead Radial lead Surface mount TO-220 43 / 50 What is one advantage of using ASCII code for data communications? It uses one character as a shift code to send numeric and special characters It is possible to transmit both uppercase and lowercase text It contains fewer information bits per character than any other code It includes built-in error correction features 44 / 50 What is the purpose of an inverter connected to a solar panel output? Prevent discharge when panel is not illuminated Reduce AC ripple on the output Maintain voltage with varying illumination levels Convert the panel's output from DC to AC 45 / 50 Which of the following is required in the identification transmissions from a balloon-borne telemetry station? All these choices are correct Call sign The output power of the balloon transmitter The station's six-character Maidenhead grid locator 46 / 50 What is a typical range for tropospheric duct propagation of microwave signals? 2,500 miles 10 miles to 50 miles 100 miles to 300 miles 1,200 miles 47 / 50 Which point on Figure E5-1 best represents the impedance of a series circuit consisting of a 300-ohm resistor and a 19-picofarad capacitor at 21.200 MHz? Point 7 Point 3 Point 1 Point 8 48 / 50 Which of the following synchronizes WSJT-X digital mode transmit/receive timing? Alignment of frequency shifts Sync-pulse timing Sync-field transmission Synchronization of computer clocks 49 / 50 Which of the following parameters does a spectrum analyzer display on the vertical and horizontal axes? Signal amplitude and time SWR and time SWR and frequency Signal amplitude and frequency 50 / 50 Which of the following apply to communications transmitted to amateur stations in foreign countries? All these choices are correct Third party traffic must be limited to that intended for the exclusive use of government and non-Government Organization (NGOs) involved in emergency relief activities Communications must be limited to those incidental to the purpose of the amateur service and remarks of a personal nature All transmissions must be in English Your score is 0% Restart quiz
