This N5HZR Correct Radio Amateur Answers Manual presents the entire FCC amateur radio Amateur Extra question pool without the distractors and is valid until June 30, 2028. This will help you study for FCC Volunteer Examiner Amateur Radio Amateur Extra test. More information is available at https:// h a m b o o k s dot o r g / c r a a m. Question 1... Why is it not legal to transmit a 3 kHz bandwidth USB signal with a carrier frequency of 14.348 MHz?... Answer 1... The upper 1 kHz of the signal is outside the 20-meter band... Question 2... When using a transceiver that displays the carrier frequency of phone signals, which of the following displayed frequencies represents the lowest frequency at which a properly adjusted LSB emission will be totally within the band?... Answer 2... 3 kHz above the lower band edge... Question 3... What is the highest legal carrier frequency on the 20-meter band for transmitting a 2.8 kHz wide USB data signal?... Answer 3... 14.1472 MHz... Question 4... May an Extra class operator answer the CQ of a station on 3.601 MHz LSB phone?... Answer 4... No, the sideband components will extend beyond the edge of the phone band segment... Question 5... Who must be in physical control of the station apparatus of an amateur station aboard any vessel or craft that is documented or registered in the United States?... Answer 5... Any person holding an FCC issued amateur license or who is authorized for alien reciprocal operation... Question 6... What is the required transmit frequency of a CW signal for channelized 60 meter operation?... Answer 6... At the center frequency of the channel... Question 7... What is the maximum power permitted on the 2200-meter band?... Answer 7... 1 watt EIRP (equivalent isotropic radiated power)... Question 8... If a station in a message forwarding system inadvertently forwards a message that is in violation of FCC rules, who is primarily accountable for the rules violation?... Answer 8... The control operator of the originating station... Question 9... Except in some parts of Alaska, what is the maximum power permitted on the 630-meter band?... Answer 9... 5 watts EIRP (equivalent isotropic radiated power)... Question 10... If an amateur station is installed aboard a ship or aircraft, what condition must be met before the station is operated?... Answer 10... Its operation must be approved by the master of the ship or the pilot in command of the aircraft... Question 11... What licensing is required when operating an amateur station aboard a US-registered vessel in international waters?... Answer 11... Any FCC-issued amateur license... Question 12... Which of the following constitutes a spurious emission?... Answer 12... An emission outside the signal’s necessary bandwidth that can be reduced or eliminated without affecting the information transmitted... Question 13... Which of the following is an acceptable bandwidth for digital voice or slow-scan TV transmissions made on the HF amateur bands?... Answer 13... 3 kHz... Question 14... Within what distance must an amateur station protect an FCC monitoring facility from harmful interference?... Answer 14... 1 mile... Question 15... What must the control operator of a repeater operating in the 70-centimeter band do if a radiolocation system experiences interference from that repeater?... Answer 15... Cease operation or make changes to the repeater that mitigate the interference... Question 16... What is the National Radio Quiet Zone?... Answer 16... An area surrounding the National Radio Astronomy Observatory... Question 17... Which of the following additional rules apply if you are erecting an amateur station antenna structure at a site at or near a public use airport?... Answer 17... You may have to notify the Federal Aviation Administration and register it with the FCC as required by Part 17 of the FCC rules... Question 18... To what type of regulations does PRB-1 apply?... Answer 18... State and local zoning... Question 19... What limitations may the FCC place on an amateur station if its signal causes interference to domestic broadcast reception, assuming that the receivers involved are of good engineering design?... Answer 19... The amateur station must avoid transmitting during certain hours on frequencies that cause the interference... Question 20... Which amateur stations may be operated under RACES rules?... Answer 20... Any FCC-licensed amateur station certified by the responsible civil defense organization for the area served... Question 21... What frequencies are authorized to an amateur station operating under RACES rules?... Answer 21... All amateur service frequencies authorized to the control operator... Question 22... What does PRB-1 require of state and local regulations affecting amateur radio antenna size and structures?... Answer 22... Reasonable accommodations of amateur radio must be made... Question 23... What is the maximum bandwidth for a data emission on 60 meters?... Answer 23... 2.8 kHz... Question 24... Which of the following apply to communications transmitted to amateur stations in foreign countries?... Answer 24... Communications must be limited to those incidental to the purpose of the amateur service and remarks of a personal nature... Question 25... How long must an operator wait after filing a notification with the Utilities Technology Council (UTC) before operating on the 2200-meter or 630-meter band?... Answer 25... Operators may operate after 30 days, providing they have not been told that their station is within 1 kilometer of PLC systems using those frequencies... Question 26... What is an IARP?... Answer 26... A permit that allows US amateurs to operate in certain countries of the Americas... Question 27... Under what situation may a station transmit third party communications while being automatically controlled?... Answer 27... Only when transmitting RTTY or data emissions... Question 28... Which of the following is required in order to operate in accordance with CEPT rules in foreign countries where permitted?... Answer 28... You must have a copy of FCC Public Notice DA 16-1048... Question 29... What notifications must be given before transmitting on the 630- or 2200-meter bands?... Answer 29... Operators must inform the Utilities Technology Council (UTC) of their call sign and coordinates of the station... Question 30... What is the maximum permissible duration of a remotely controlled station’s transmissions if its control link malfunctions?... Answer 30... 3 minutes... Question 31... What is the highest modulation index permitted at the highest modulation frequency for angle modulation below 29.0 MHz?... Answer 31... 1.0... Question 32... What is the maximum mean power level for a spurious emission below 30 MHz with respect to the fundamental emission?... Answer 32... - 43 dB... Question 33... Which of the following operating arrangements allows an FCC-licensed US citizen to operate in many European countries, and amateurs from many European countries to operate in the US?... Answer 33... CEPT... Question 34... In what portion of the 630-meter band are phone emissions permitted?... Answer 34... The entire band... Question 35... What is the definition of telemetry?... Answer 35... One-way transmission of measurements at a distance from the measuring instrument... Question 36... Which of the following may transmit encrypted messages?... Answer 36... Telecommand signals from a space telecommand station... Question 37... What is a space telecommand station?... Answer 37... An amateur station that transmits communications to initiate, modify, or terminate functions of a space station... Question 38... Which of the following is required in the identification transmissions from a balloon-borne telemetry station?... Answer 38... Call sign... Question 39... What must be posted at the location of a station being operated by telecommand on or within 50 kilometers of the Earth’s surface?... Answer 39... A photocopy of the station license... Answer 39... A label with the name, address, and telephone number of the station licensee... Answer 39... A label with the name, address, and telephone number of the control operator... Answer 39... All these choices are correct... Question 40... What is the maximum permitted transmitter output power when operating a model craft by telecommand?... Answer 40... 1 watt... Question 41... Which of the following HF amateur bands include allocations for space stations?... Answer 41... 40 meters, 20 meters, 15 meters, and 10 meters... Question 42... Which VHF amateur bands have frequencies authorized for space stations?... Answer 42... 2 meters... Question 43... Which UHF amateur bands have frequencies authorized for space stations?... Answer 43... 70 centimeters and 13 centimeters... Question 44... Which amateur stations are eligible to be telecommand stations of space stations, subject to the privileges of the class of operator license held by the control operator of the station?... Answer 44... Any amateur station so designated by the space station licensee... Question 45... Which amateur stations are eligible to operate as Earth stations?... Answer 45... Any amateur station, subject to the privileges of the class of operator license held by the control operator... Question 46... Which of the following amateur stations may transmit one-way communications?... Answer 46... A space station, beacon station, or telecommand station... Question 47... For which types of out-of-pocket expenses do the Part 97 rules state that VEs and VECs may be reimbursed?... Answer 47... Preparing, processing, administering, and coordinating an examination for an amateur radio operator license... Question 48... Who is tasked by Part 97 with maintaining the pools of questions for all US amateur license examinations?... Answer 48... The VECs... Question 49... What is a Volunteer Examiner Coordinator?... Answer 49... An organization that has entered into an agreement with the FCC to coordinate, prepare, and administer amateur operator license examinations... Question 50... What is required to be accredited as a Volunteer Examiner?... Answer 50... A VEC must confirm that the VE applicant meets FCC requirements to serve as an examiner... Question 51... What must the VE team do with the application form if the examinee does not pass the exam?... Answer 51... Return the application document to the examinee... Question 52... Who is responsible for the proper conduct and necessary supervision during an amateur operator license examination session?... Answer 52... Each administering VE... Question 53... What should a VE do if a candidate fails to comply with the examiner’s instructions during an amateur operator license examination?... Answer 53... Immediately terminate the candidate’s examination... Question 54... To which of the following examinees may a VE not administer an examination?... Answer 54... Relatives of the VE as listed in the FCC rules... Question 55... What may be the penalty for a VE who fraudulently administers or certifies an examination?... Answer 55... Revocation of the VE’s amateur station license grant and the suspension of the VE’s amateur operator license grant... Question 56... What must the administering VEs do after the administration of a successful examination for an amateur operator license?... Answer 56... They must submit the application document to the coordinating VEC according to the coordinating VEC instructions... Question 57... What must the VE team do if an examinee scores a passing grade on all examination elements needed for an upgrade or new license?... Answer 57... Three VEs must certify that the examinee is qualified for the license grant and that they have complied with the administering VE requirements... Question 58... On what frequencies are spread spectrum transmissions permitted?... Answer 58... Only on amateur frequencies above 222 MHz... Question 59... What privileges are authorized in the US to persons holding an amateur service license granted by the government of Canada?... Answer 59... The operating terms and conditions of the Canadian amateur service license, not to exceed US Amateur Extra class license privileges... Question 60... 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?... Answer 60... The amplifier is constructed or modified by an amateur radio operator for use at an amateur station... Question 61... Which of the following geographic descriptions approximately describes "Line A"?... Answer 61... A line roughly parallel to and south of the border between the US and Canada... Question 62... Amateur stations may not transmit in which of the following frequency segments if they are located in the contiguous 48 states and north of Line A?... Answer 62... 420 MHz - 430 MHz... Question 63... Under what circumstances might the FCC issue a Special Temporary Authority (STA) to an amateur station?... Answer 63... To provide for experimental amateur communications... Question 64... When may an amateur station send a message to a business?... Answer 64... When neither the amateur nor their employer has a pecuniary interest in the communications... Question 65... Which of the following types of amateur station communications are prohibited?... Answer 65... Communications transmitted for hire or material compensation, except as otherwise provided in the rules... Question 66... Which of the following cannot be transmitted over an amateur radio mesh network?... Answer 66... Messages encoded to obscure their meaning... Question 67... Who may be the control operator of an auxiliary station?... Answer 67... Only Technician, General, Advanced, or Amateur Extra class operators... Question 68... Which of the following best describes one of the standards that must be met by an external RF power amplifier if it is to qualify for a grant of FCC certification?... Answer 68... It must satisfy the FCC’s spurious emission standards when operated at the lesser of 1500 watts or its full output power... Question 69... What is the direction of an ascending pass for an amateur satellite?... Answer 69... From south to north... Question 70... Which of the following is characteristic of an inverting linear transponder?... Answer 70... Doppler shift is reduced because the uplink and downlink shifts are in opposite directions... Answer 70... Signal position in the band is reversed... Answer 70... Upper sideband on the uplink becomes lower sideband on the downlink, and vice versa... Answer 70... All these choices are correct... Question 71... How is an upload signal processed by an inverting linear transponder?... Answer 71... The signal is mixed with a local oscillator signal and the difference product is transmitted... Question 72... What is meant by the “mode” of an amateur radio satellite?... Answer 72... The satellite’s uplink and downlink frequency bands... Question 73... What do the letters in a satellite’s mode designator specify?... Answer 73... The uplink and downlink frequency ranges... Question 74... What are Keplerian elements?... Answer 74... Parameters that define the orbit of a satellite... Question 75... Which of the following types of signals can be relayed through a linear transponder?... Answer 75... FM and CW... Answer 75... SSB and SSTV... Answer 75... PSK and packet... Answer 75... All these choices are correct... Question 76... Why should effective radiated power (ERP) be limited to a satellite that uses a linear transponder?... Answer 76... To avoid reducing the downlink power to all other users... Question 77... What do the terms “L band” and “S band” specify?... Answer 77... The 23- and 13-centimeter bands... Question 78... What type of satellite appears to stay in one position in the sky?... Answer 78... Geostationary... Question 79... What type of antenna can be used to minimize the effects of spin modulation and Faraday rotation?... Answer 79... A circularly polarized antenna... Question 80... What is the purpose of digital store-and-forward functions on an amateur radio satellite?... Answer 80... To hold digital messages in the satellite for later download... Question 81... Which of the following techniques is used by digital satellites to relay messages?... Answer 81... Store-and-forward... Question 82... In digital television, what does a coding rate of 3/4 mean?... Answer 82... 25% of the data sent is forward error correction data... Question 83... How many horizontal lines make up a fast-scan (NTSC) television frame?... Answer 83... 525... Question 84... How is an interlaced scanning pattern generated in a fast-scan (NTSC) television system?... Answer 84... By scanning odd-numbered lines in one field and even-numbered lines in the next... Question 85... How is color information sent in analog SSTV?... Answer 85... Color lines are sent sequentially... Question 86... Which of the following describes the use of vestigial sideband in analog fast-scan TV transmissions?... Answer 86... Vestigial sideband reduces the bandwidth while increasing the fidelity of low frequency video components... Question 87... What is vestigial sideband modulation?... Answer 87... Amplitude modulation in which one complete sideband and a portion of the other are transmitted... Question 88... Which types of modulation are used for amateur television DVB-T signals?... Answer 88... QAM and QPSK... Question 89... What technique allows commercial analog TV receivers to be used for fast-scan TV operations on the 70-centimeter band?... Answer 89... Transmitting on channels shared with cable TV... Question 90... What kind of receiver can be used to receive and decode SSTV using the Digital Radio Mondiale (DRM) protocol?... Answer 90... SSB... Question 91... What aspect of an analog slow-scan television signal encodes the brightness of the picture?... Answer 91... Tone frequency... Question 92... What is the function of the vertical interval signaling (VIS) code sent as part of an SSTV transmission?... Answer 92... To identify the SSTV mode being used... Question 93... What signals SSTV receiving software to begin a new picture line?... Answer 93... Specific tone frequencies... Question 94... What indicator is required to be used by US-licensed operators when operating a station via remote control and the remote transmitter is located in the US?... Answer 94... No additional indicator is required... Question 95... Which of the following file formats is used for exchanging amateur radio log data?... Answer 95... ADIF... Question 96... From which of the following bands is amateur radio contesting generally excluded?... Answer 96... 30 meters... Question 97... Which of the following frequencies can be used for amateur radio mesh networks?... Answer 97... Frequencies shared with various unlicensed wireless data services... Question 98... What is the function of a DX QSL Manager?... Answer 98... Handle the receiving and sending of confirmations for a DX station... Question 99... During a VHF/UHF contest, in which band segment would you expect to find the highest level of SSB or CW activity?... Answer 99... In the weak signal segment of the band, with most of the activity near the calling frequency... Question 100... What is the Cabrillo format?... Answer 100... A standard for submission of electronic contest logs... Question 101... Which of the following contacts may be confirmed through the Logbook of The World (LoTW)?... Answer 101... Special event contacts between stations in the US... Answer 101... Contacts between a US station and a non-US station... Answer 101... Contacts for Worked All States credit... Answer 101... All these choices are correct... Question 102... What type of equipment is commonly used to implement an amateur radio mesh network?... Answer 102... A wireless router running custom firmware... Question 103... Why do DX stations often transmit and receive on different frequencies?... Answer 103... Because the DX station may be transmitting on a frequency that is prohibited to some responding stations... Answer 103... To separate the calling stations from the DX station... Answer 103... To improve operating efficiency by reducing interference... Answer 103... All these choices are correct... Question 104... How should you generally identify your station when attempting to contact a DX station during a contest or in a pileup?... Answer 104... Send your full call sign once or twice... Question 105... What indicates the delay between a control operator action and the corresponding change in the transmitted signal?... Answer 105... Latency... Question 106... Which of the following digital modes is designed for meteor scatter communications?... Answer 106... MSK144... Question 107... What information replaces signal-to-noise ratio when using the FT8 or FT4 modes in a VHF contest?... Answer 107... Grid square... Question 108... Which of the following digital modes is designed for EME communications?... Answer 108... Q65... Question 109... What technology is used for real-time tracking of balloons carrying amateur radio transmitters?... Answer 109... APRS... Question 110... What is the characteristic of the JT65 mode?... Answer 110... Decodes signals with a very low signal-to-noise ratio... Question 111... Which of the following is a method for establishing EME contacts?... Answer 111... Time-synchronous transmissions alternating between stations... Question 112... What digital protocol is used by APRS?... Answer 112... AX.25... Question 113... What type of packet frame is used to transmit APRS beacon data?... Answer 113... Unnumbered Information... Question 114... What type of modulation is used by JT65?... Answer 114... Multitone AFSK... Question 115... What does the packet path WIDE3-1 designate?... Answer 115... Three digipeater hops are requested with one remaining... Question 116... How do APRS stations relay data?... Answer 116... By packet digipeaters... Question 117... Which of the following types of modulation is used for data emissions below 30 MHz?... Answer 117... FSK... Question 118... Which of the following synchronizes WSJT-X digital mode transmit/receive timing?... Answer 118... Synchronization of computer clocks... Question 119... To what does the "4" in FT4 refer?... Answer 119... Four-tone continuous-phase frequency shift keying... Question 120... Which of the following is characteristic of the FST4 mode?... Answer 120... Four-tone Gaussian frequency shift keying... Answer 120... Variable transmit/receive periods... Answer 120... Seven different tone spacings... Answer 120... All these choices are correct... Question 121... Which of these digital modes does not support keyboard-to-keyboard operation?... Answer 121... WSPR... Question 122... What is the length of an FT8 transmission cycle?... Answer 122... 15 seconds... Question 123... How does Q65 differ from JT65?... Answer 123... Multiple receive cycles are averaged... Question 124... Which of the following HF digital modes can be used to transfer binary files?... Answer 124... PACTOR... Question 125... Which of the following HF digital modes uses variable-length character coding?... Answer 125... PSK31... Question 126... Which of these digital modes has the narrowest bandwidth?... Answer 126... FT8... Question 127... What is the difference between direct FSK and audio FSK?... Answer 127... Direct FSK modulates the transmitter VFO... Question 128... How do ALE stations establish contact?... Answer 128... ALE constantly scans a list of frequencies, activating the radio when the designated call sign is received... Question 129... Which of these digital modes has the highest data throughput under clear communication conditions?... Answer 129... PACTOR IV... Question 130... What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by EME?... Answer 130... 12,000 miles, if the moon is “visible” by both stations... Question 131... What characterizes libration fading of an EME signal?... Answer 131... A fluttery, irregular fading... Question 132... When scheduling EME contacts, which of these conditions will generally result in the least path loss?... Answer 132... When the Moon is at perigee... Question 133... In what direction does an electromagnetic wave travel?... Answer 133... It travels at a right angle to the electric and magnetic fields... Question 134... How are the component fields of an electromagnetic wave oriented?... Answer 134... They are at right angles... Question 135... What should be done to continue a long-distance contact when the MUF for that path decreases due to darkness?... Answer 135... Switch to a lower frequency HF band... Question 136... Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?... Answer 136... Large bodies of water... Question 137... When a meteor strikes the Earth’s atmosphere, a linear ionized region is formed at what region of the ionosphere?... Answer 137... The E region... Question 138... Which of the following frequency ranges is most suited for meteor-scatter communications?... Answer 138... 28 MHz - 148 MHz... Question 139... What determines the speed of electromagnetic waves through a medium?... Answer 139... The index of refraction... Question 140... What is a typical range for tropospheric duct propagation of microwave signals?... Answer 140... 100 miles to 300 miles... Question 141... What is most likely to result in auroral propagation?... Answer 141... Severe geomagnetic storms... Question 142... Which of these emission modes is best for auroral propagation?... Answer 142... CW... Question 143... What are circularly polarized electromagnetic waves?... Answer 143... Waves with rotating electric and magnetic fields... Question 144... Where is transequatorial propagation (TEP) most likely to occur?... Answer 144... Between points separated by 2,000 miles to 3,000 miles over a path perpendicular to the geomagnetic equator... Question 145... What is the approximate maximum range for signals using transequatorial propagation?... Answer 145... 5,000 miles... Question 146... At what time of day is transequatorial propagation most likely to occur?... Answer 146... Afternoon or early evening... Question 147... What are “extraordinary” and “ordinary” waves?... Answer 147... Independently propagating, elliptically polarized waves created in the ionosphere... Question 148... Which of the following paths is most likely to support long-distance propagation on 160 meters?... Answer 148... A path entirely in darkness... Question 149... On which of the following amateur bands is long-path propagation most frequent?... Answer 149... 40 meters and 20 meters... Question 150... What effect does lowering a signal’s transmitted elevation angle have on ionospheric HF skip propagation?... Answer 150... The distance covered by each hop increases... Question 151... How does the maximum range of ground-wave propagation change when the signal frequency is increased?... Answer 151... It decreases... Question 152... At what time of year is sporadic-E propagation most likely to occur?... Answer 152... Around the solstices, especially the summer solstice... Question 153... What is the effect of chordal-hop propagation?... Answer 153... The signal experiences less loss compared to multi-hop propagation, which uses Earth as a reflector... Question 154... At what time of day is sporadic-E propagation most likely to occur?... Answer 154... Between sunrise and sunset... Question 155... What is chordal-hop propagation?... Answer 155... Successive ionospheric refractions without an intermediate reflection from the ground... Question 156... What type of polarization is supported by ground-wave propagation?... Answer 156... Vertical... Question 157... What is the cause of short-term radio blackouts?... Answer 157... Solar flares... Question 158... What is indicated by a rising A-index or K-index?... Answer 158... Increasing disturbance of the geomagnetic field... Question 159... Which of the following signal paths is most likely to experience high levels of absorption when the A-index or K-index is elevated?... Answer 159... Through the auroral oval... Question 160... What does the value of Bz (B sub z) represent?... Answer 160... North-south strength of the interplanetary magnetic field... Question 161... What orientation of Bz (B sub z) increases the likelihood that charged particles from the Sun will cause disturbed conditions?... Answer 161... Southward... Question 162... How does the VHF/UHF radio horizon compare to the geographic horizon?... Answer 162... It is approximately 15 percent farther... Question 163... Which of the following indicates the greatest solar flare intensity?... Answer 163... Class X... Question 164... Which of the following is the space-weather term for an extreme geomagnetic storm?... Answer 164... G5... Question 165... What type of data is reported by amateur radio propagation reporting networks?... Answer 165... Digital-mode and CW signals... Question 166... What does the 304A solar parameter measure?... Answer 166... UV emissions at 304 angstroms, correlated to the solar flux index... Question 167... What does VOACAP software model?... Answer 167... HF propagation... Question 168... Which of the following is indicated by a sudden rise in radio background noise across a large portion of the HF spectrum?... Answer 168... A coronal mass ejection impact or a solar flare has occurred... Question 169... Which of the following limits the highest frequency signal that can be accurately displayed on a digital oscilloscope?... Answer 169... Sampling rate of the analog-to-digital converter... Question 170... Which of the following parameters does a spectrum analyzer display on the vertical and horizontal axes?... Answer 170... Signal amplitude and frequency... Question 171... Which of the following test instruments is used to display spurious signals and/or intermodulation distortion products generated by an SSB transmitter?... Answer 171... Spectrum analyzer... Question 172... How is compensation of an oscilloscope probe performed?... Answer 172... A square wave is displayed, and the probe is adjusted until the horizontal portions of the displayed wave are as nearly flat as possible... Question 173... What is the purpose of using a prescaler with a frequency counter?... Answer 173... Reduce the signal frequency to within the counter's operating range... Question 174... What is the effect of aliasing on a digital oscilloscope when displaying a waveform?... Answer 174... A false, jittery low-frequency version of the waveform is displayed... Question 175... Which of the following is an advantage of using an antenna analyzer compared to an SWR bridge?... Answer 175... Antenna analyzers compute SWR and impedance automatically... Question 176... Which of the following is used to measure SWR?... Answer 176... Directional wattmeter... Answer 176... Vector network analyzer... Answer 176... Antenna analyzer... Answer 176... All these choices are correct... Question 177... Which of the following is good practice when using an oscilloscope probe?... Answer 177... Minimize the length of the probe's ground connection... Question 178... Which trigger mode is most effective when using an oscilloscope to measure a linear power supply’s output ripple?... Answer 178... Line... Question 179... Which of the following can be measured with an antenna analyzer?... Answer 179... Velocity factor... Answer 179... Cable length... Answer 179... Resonant frequency of a tuned circuit... Answer 179... All these choices are correct... Question 180... Which of the following factors most affects the accuracy of a frequency counter?... Answer 180... Time base accuracy... Question 181... What is the significance of voltmeter sensitivity expressed in ohms per volt?... Answer 181... The full scale reading of the voltmeter multiplied by its ohms per volt rating is the input impedance of the voltmeter... Question 182... Which S parameter is equivalent to forward gain?... Answer 182... S21... Question 183... Which S parameter represents input port return loss or reflection coefficient (equivalent to VSWR)?... Answer 183... S11... Question 184... What three test loads are used to calibrate an RF vector network analyzer?... Answer 184... Short circuit, open circuit, and 50 ohms... Question 185... 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?... Answer 185... 75 watts... Question 186... What do the subscripts of S parameters represent?... Answer 186... The port or ports at which measurements are made... Question 187... Which of the following can be used to determine the Q of a series-tuned circuit?... Answer 187... The bandwidth of the circuit's frequency response... Question 188... Which of the following can be measured by a two-port vector network analyzer?... Answer 188... Filter frequency response... Question 189... Which of the following methods measures intermodulation distortion in an SSB transmitter?... Answer 189... Modulate the transmitter using two AF signals having non-harmonically related frequencies and observe the RF output with a spectrum analyzer... Question 190... Which of the following can be measured with a vector network analyzer?... Answer 190... Input impedance... Answer 190... Output impedance... Answer 190... Reflection coefficient... Answer 190... All these choices are correct... Question 191... What is an effect of excessive phase noise in an SDR receiver’s master clock oscillator?... Answer 191... It can combine with strong signals on nearby frequencies to generate interference... Question 192... Which of the following receiver circuits can be effective in eliminating interference from strong out-of-band signals?... Answer 192... A front-end filter or preselector... Question 193... What is the term for the suppression in an FM receiver of one signal by another stronger signal on the same frequency?... Answer 193... Capture effect... Question 194... What is the noise figure of a receiver?... Answer 194... The ratio in dB of the noise generated by the receiver to the theoretical minimum noise... Question 195... What does a receiver noise floor of -174 dBm represent?... Answer 195... The theoretical noise in a 1 Hz bandwidth at the input of a perfect receiver at room temperature... Question 196... How much does increasing a receiver’s bandwidth from 50 Hz to 1,000 Hz increase the receiver’s noise floor?... Answer 196... 13 dB... Question 197... What does the MDS of a receiver represent?... Answer 197... The minimum discernible signal... Question 198... An SDR receiver is overloaded when input signals exceed what level?... Answer 198... The reference voltage of the analog-to-digital converter... Question 199... Which of the following choices is a good reason for selecting a high IF for a superheterodyne HF or VHF communications receiver?... Answer 199... Easier for front-end circuitry to eliminate image responses... Question 200... What is an advantage of having a variety of receiver bandwidths from which to select?... Answer 200... Receive bandwidth can be set to match the modulation bandwidth, maximizing signal-to-noise ratio and minimizing interference... Question 201... Why does input attenuation reduce receiver overload on the lower frequency HF bands with little or no impact on signal-to-noise ratio?... Answer 201... Atmospheric noise is generally greater than internally generated noise even after attenuation... Question 202... How does a narrow-band roofing filter affect receiver performance?... Answer 202... It improves blocking dynamic range by attenuating strong signals near the receive frequency... Question 203... What is reciprocal mixing?... Answer 203... Local oscillator phase noise mixing with adjacent strong signals to create interference to desired signals... Question 204... What is the purpose of the receiver IF Shift control?... Answer 204... To reduce interference from stations transmitting on adjacent frequencies... Question 205... What is meant by the blocking dynamic range of a receiver?... Answer 205... The difference in dB between the noise floor and the level of an incoming signal that will cause 1 dB of gain compression... Question 206... Which of the following describes problems caused by poor dynamic range in a receiver?... Answer 206... Spurious signals caused by cross modulation and desensitization from strong adjacent signals... Question 207... What creates intermodulation interference between two repeaters in close proximity?... Answer 207... The output signals mix in the final amplifier of one or both transmitters... Question 208... Which of the following is used to reduce or eliminate intermodulation interference in a repeater caused by a nearby transmitter?... Answer 208... A properly terminated circulator at the output of the repeater’s transmitter... Question 209... What transmitter frequencies would create an intermodulation-product signal in a receiver tuned to 146.70 MHz when a nearby station transmits on 146.52 MHz?... Answer 209... 146.34 MHz and 146.61 MHz... Question 210... What is the term for the reduction in receiver sensitivity caused by a strong signal near the received frequency?... Answer 210... Desensitization... Question 211... Which of the following reduces the likelihood of receiver desensitization?... Answer 211... Insert attenuation before the first RF stage... Question 212... What causes intermodulation in an electronic circuit?... Answer 212... Nonlinear circuits or devices... Question 213... What is the purpose of the preselector in a communications receiver?... Answer 213... To increase the rejection of signals outside the band being received... Question 214... What does a third-order intercept level of 40 dBm mean with respect to receiver performance?... Answer 214... 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... Question 215... Why are odd-order intermodulation products, created within a receiver, of particular interest compared to other products?... Answer 215... Odd-order products of two signals in the band being received are also likely to be within the band... Question 216... What is the link margin in a system with a transmit power level of 10 W (+40 dBm), a system antenna gain of 10 dBi, a cable loss of 3 dB, a path loss of 136 dB, a receiver minimum discernable signal of -103 dBm, and a required signal-to-noise ratio of 6 dB?... Answer 216... +8dB... Question 217... What is the received signal level with a transmit power of 10 W (+40 dBm), a transmit antenna gain of 6 dBi, a receive antenna gain of 3 dBi, and a path loss of 100 dB?... Answer 217... -51 dBm... Question 218... What power level does a receiver minimum discernible signal of -100 dBm represent?... Answer 218... 0.1 picowatts... Question 219... What problem can occur when using an automatic notch filter (ANF) to remove interfering carriers while receiving CW signals?... Answer 219... Removal of the CW signal as well as the interfering carrier... Question 220... Which of the following types of noise can often be reduced by a digital noise reduction?... Answer 220... Broadband white noise... Answer 220... Ignition noise... Answer 220... Power line noise... Answer 220... All these choices are correct... Question 221... Which of the following types of noise are removed by a noise blanker?... Answer 221... Impulse noise... Question 222... How can conducted noise from an automobile battery charging system be suppressed?... Answer 222... By installing ferrite chokes on the charging system leads... Question 223... What is used to suppress radio frequency interference from a line-driven AC motor?... Answer 223... A brute-force AC-line filter in series with the motor’s power leads... Question 224... What type of electrical interference can be caused by computer network equipment?... Answer 224... The appearance of unstable modulated or unmodulated signals at specific frequencies... Question 225... Which of the following can cause shielded cables to radiate or receive interference?... Answer 225... Common-mode currents on the shield and conductors... Question 226... What current flows equally on all conductors of an unshielded multiconductor cable?... Answer 226... Common-mode current... Question 227... What undesirable effect can occur when using a noise blanker?... Answer 227... Strong signals may be distorted and appear to cause spurious emissions... Question 228... Which of the following can create intermittent loud roaring or buzzing AC line interference?... Answer 228... Arcing contacts in a thermostatically controlled device... Answer 228... A defective doorbell or doorbell transformer inside a nearby residence... Answer 228... A malfunctioning illuminated advertising display... Answer 228... All these choices are correct... Question 229... What could be the cause of local AM broadcast band signals combining to generate spurious signals on the MF or HF bands?... Answer 229... Nearby corroded metal connections are mixing and reradiating the broadcast signals... Question 230... What causes interference received as a series of carriers at regular intervals across a wide frequency range?... Answer 230... Switch-mode power supplies... Question 231... Where should a station AC surge protector be installed?... Answer 231... On the single point ground panel... Question 232... What is the purpose of a single point ground panel?... Answer 232... Ensure all lightning protectors activate at the same time... Question 233... What can cause the voltage across reactances in a series RLC circuit to be higher than the voltage applied to the entire circuit?... Answer 233... Resonance... Question 234... What is the resonant frequency of an RLC circuit if R is 22 ohms, L is 50 microhenries, and C is 40 picofarads?... Answer 234... 3.56 MHz... Question 235... What is the magnitude of the impedance of a series RLC circuit at resonance?... Answer 235... Approximately equal to circuit resistance... Question 236... What is the magnitude of the impedance of a parallel RLC circuit at resonance?... Answer 236... Approximately equal to circuit resistance... Question 237... What is the result of increasing the Q of an impedance-matching circuit?... Answer 237... Matching bandwidth is decreased... Question 238... What is the magnitude of the circulating current within the components of a parallel LC circuit at resonance?... Answer 238... It is at a maximum... Question 239... What is the magnitude of the current at the input of a parallel RLC circuit at resonance?... Answer 239... Minimum... Question 240... What is the phase relationship between the current through and the voltage across a series resonant circuit at resonance?... Answer 240... The voltage and current are in phase... Question 241... How is the Q of an RLC parallel resonant circuit calculated?... Answer 241... Resistance divided by the reactance of either the inductance or capacitance... Question 242... What is the resonant frequency of an RLC circuit if R is 33 ohms, L is 50 microhenries, and C is 10 picofarads?... Answer 242... 7.12 MHz... Question 243... What is the half-power bandwidth of a resonant circuit that has a resonant frequency of 7.1 MHz and a Q of 150?... Answer 243... 47.3 kHz... Question 244... What is the half-power bandwidth of a resonant circuit that has a resonant frequency of 3.7 MHz and a Q of 118?... Answer 244... 31.4 kHz... Question 245... What is an effect of increasing Q in a series resonant circuit?... Answer 245... Internal voltages increase... Question 246... What is the term for the time required for the capacitor in an RC circuit to be charged to 63.2% of the applied voltage or to discharge to 36.8% of its initial voltage?... Answer 246... One time constant... Question 247... What letter is commonly used to represent susceptance?... Question 248... ... Answer 248... How is impedance in polar form converted to an equivalent admittance?... Answer 248... Take the reciprocal of the magnitude and change the sign of the angle... Question 249... What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors, all in parallel?... Answer 249... 220 seconds... Question 250... What is the effect on the magnitude of pure reactance when it is converted to susceptance?... Answer 250... It is replaced by its reciprocal... Question 251... What is susceptance?... Answer 251... The imaginary part of admittance... Question 252... What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 500 ohms, R is 1 kilohm, and XL is 250 ohms?... Answer 252... 14.0 degrees with the voltage lagging the current... Question 253... What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 300 ohms, R is 100 ohms, and XL is 100 ohms?... Answer 253... 63 degrees with the voltage lagging the current... Question 254... What is the relationship between the AC current through a capacitor and the voltage across a capacitor?... Answer 254... Current leads voltage by 90 degrees... Question 255... What is the relationship between the AC current through an inductor and the voltage across an inductor?... Answer 255... Voltage leads current by 90 degrees... Question 256... What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 25 ohms, R is 100 ohms, and XL is 75 ohms?... Answer 256... 27 degrees with the voltage leading the current... Question 257... What is admittance?... Answer 257... The inverse of impedance... Question 258... Which of the following represents pure capacitive reactance of 100 ohms in rectangular notation?... Answer 258... 0 - j100... Question 259... How are impedances described in polar coordinates?... Answer 259... By magnitude and phase angle... Question 260... Which of the following represents a pure inductive reactance in polar coordinates?... Answer 260... A positive 90 degree phase angle... Question 261... What type of Y-axis scale is most often used for graphs of circuit frequency response?... Answer 261... Logarithmic... Question 262... What kind of diagram is used to show the phase relationship between impedances at a given frequency?... Answer 262... Phasor diagram... Question 263... What does the impedance 50 - j25 ohms represent?... Answer 263... 50 ohms resistance in series with 25 ohms capacitive reactance... Question 264... Where is the impedance of a pure resistance plotted on rectangular coordinates?... Answer 264... On the horizontal axis... Question 265... What coordinate system is often used to display the phase angle of a circuit containing resistance, inductive, and/or capacitive reactance?... Answer 265... Polar coordinates... Question 266... When using rectangular coordinates to graph the impedance of a circuit, what do the axes represent?... Answer 266... The X axis represents the resistive component, and the Y axis represents the reactive component... Question 267... What is the result of conductor skin effect?... Answer 267... Resistance increases as frequency increases because RF current flows closer to the surface... Question 268... Why is it important to keep lead lengths short for components used in circuits for VHF and above?... Answer 268... To minimize inductive reactance... Question 269... What is the phase relationship between current and voltage for reactive power?... Answer 269... They are 90 degrees out of phase... Question 270... Why are short connections used at microwave frequencies?... Answer 270... To reduce phase shift along the connection... Question 271... What parasitic characteristic causes electrolytic capacitors to be unsuitable for use at RF?... Answer 271... Inductance... Question 272... What parasitic characteristic creates an inductor’s self-resonance?... Answer 272... Inter-turn capacitance... Question 273... What combines to create the self-resonance of a component?... Answer 273... The component’s nominal and parasitic reactance... Question 274... What is the primary cause of loss in film capacitors at RF?... Answer 274... Skin effect... Question 275... What happens to reactive power in ideal inductors and capacitors?... Answer 275... Energy is stored in magnetic or electric fields, but power is not dissipated... Question 276... As a conductor’s diameter increases, what is the effect on its electrical length?... Answer 276... It increases... Question 277... How much real power is consumed in a circuit consisting of a 100-ohm resistor in series with a 100-ohm inductive reactance drawing 1 ampere?... Answer 277... 100 watts... Question 278... What is reactive power?... Answer 278... Wattless, nonproductive power... Question 279... In what application is gallium arsenide used as a semiconductor material?... Answer 279... In microwave circuits... Question 280... Which of the following semiconductor materials contains excess free electrons?... Answer 280... N-type... Question 281... Why does a PN-junction diode not conduct current when reverse biased?... Answer 281... Holes in P-type material and electrons in the N-type material are separated by the applied voltage, widening the depletion region... Question 282... What is the name given to an impurity atom that adds holes to a semiconductor crystal structure?... Answer 282... Acceptor impurity... Question 283... How does DC input impedance at the gate of a field-effect transistor (FET) compare with that of a bipolar transistor?... Answer 283... An FET has higher input impedance... Question 284... What is the beta of a bipolar junction transistor?... Answer 284... The change in collector current with respect to the change in base current... Question 285... Which of the following indicates that a silicon NPN junction transistor is biased on?... Answer 285... Base-to-emitter voltage of approximately 0.6 volts to 0.7 volts... Question 286... What is the term for the frequency at which the grounded-base current gain of a bipolar junction transistor has decreased to 0.7 of the gain obtainable at 1 kHz?... Answer 286... Alpha cutoff frequency... Question 287... What is a depletion-mode field-effect transistor (FET)?... Answer 287... An FET that exhibits a current flow between source and drain when no gate voltage is applied... Question 288... What is the purpose of connecting Zener diodes between a MOSFET gate and its source or drain?... Answer 288... To protect the gate from static damage... Question 289... What is the most useful characteristic of a Zener diode?... Answer 289... A constant voltage drop under conditions of varying current... Question 290... Which characteristic of a Schottky diode makes it a better choice than a silicon junction diode for use as a power supply rectifier?... Answer 290... Lower forward voltage drop... Question 291... What property of an LED's semiconductor material determines its forward voltage drop?... Answer 291... Band gap... Question 292... What type of semiconductor device is designed for use as a voltage-controlled capacitor?... Answer 292... Varactor diode... Question 293... What characteristic of a PIN diode makes it useful as an RF switch?... Answer 293... Low junction capacitance... Question 294... Which of the following is a common use of a Schottky diode?... Answer 294... As a VHF/UHF mixer or detector... Question 295... What causes a junction diode to fail from excessive current?... Answer 295... Excessive junction temperature... Question 296... Which of the following is a Schottky barrier diode?... Answer 296... Metal-semiconductor junction... Question 297... What is a common use for point-contact diodes?... Answer 297... As an RF detector... Question 298... What is used to control the attenuation of RF signals by a PIN diode?... Answer 298... Forward DC bias current... Question 299... What is the function of hysteresis in a comparator?... Answer 299... To prevent input noise from causing unstable output signals... Question 300... What happens when the level of a comparator’s input signal crosses the threshold voltage?... Answer 300... The comparator changes its output state... Question 301... What is tri-state logic?... Answer 301... Logic devices with 0, 1, and high-impedance output states... Question 302... Which of the following is an advantage of BiCMOS logic?... Answer 302... It has the high input impedance of CMOS and the low output impedance of bipolar transistors... Question 303... Which of the following digital logic families has the lowest power consumption?... Answer 303... CMOS... Question 304... Why do CMOS digital integrated circuits have high immunity to noise on the input signal or power supply?... Answer 304... The input switching threshold is about half the power supply voltage... Question 305... What best describes a pull-up or pull-down resistor?... Answer 305... A resistor connected to the positive or negative supply used to establish a voltage when an input or output is an open circuit... Question 306... What is used to design the configuration of a field-programmable gate array (FPGA)?... Answer 306... Hardware description language (HDL)... Question 307... What is piezoelectricity?... Answer 307... A characteristic of materials that generate a voltage when stressed and that flex when a voltage is applied... Question 308... What is the equivalent circuit of a quartz crystal?... Answer 308... Series RLC in parallel with a shunt C representing electrode and stray capacitance... Question 309... Which of the following is an aspect of the piezoelectric effect?... Answer 309... Mechanical deformation of material due to the application of a voltage... Question 310... Why are cores of inductors and transformers sometimes constructed of thin layers?... Answer 310... To reduce power loss from eddy currents in the core... Question 311... How do ferrite and powdered iron compare for use in an inductor core?... Answer 311... Ferrite cores generally require fewer turns to produce a given inductance value... Question 312... What core material property determines the inductance of an inductor?... Answer 312... Permeability... Question 313... What is the current that flows in the primary winding of a transformer when there is no load on the secondary winding?... Answer 313... Magnetizing current... Question 314... Which of the following materials has the highest temperature stability of its magnetic characteristics?... Answer 314... Powdered iron... Question 315... What devices are commonly used as VHF and UHF parasitic suppressors at the input and output terminals of a transistor HF amplifier?... Answer 315... Ferrite beads... Question 316... What is a primary advantage of using a toroidal core instead of a solenoidal core in an inductor?... Answer 316... Toroidal cores confine most of the magnetic field within the core material... Question 317... Which type of core material decreases inductance when inserted into a coil?... Answer 317... Brass... Question 318... What causes inductor saturation?... Answer 318... Operation at excessive magnetic flux... Question 319... Why is gallium arsenide (GaAs) useful for semiconductor devices operating at UHF and higher frequencies?... Answer 319... Higher electron mobility... Question 320... Which of the following device packages is a through-hole type?... Answer 320... DIP... Question 321... Which of the following materials supports the highest frequency of operation when used in MMICs?... Answer 321... Gallium nitride... Question 322... Which is the most common input and output impedance of MMICs?... Answer 322... 50 ohms... Question 323... Which of the following noise figure values is typical of a low-noise UHF preamplifier?... Answer 323... 0.5 dB... Question 324... What characteristics of MMICs make them a popular choice for VHF through microwave circuits?... Answer 324... Controlled gain, low noise figure, and constant input and output impedance over the specified frequency range... Question 325... What type of transmission line is often used for connections to MMICs?... Answer 325... Microstrip... Question 326... How is power supplied to the most common type of MMIC?... Answer 326... Through a resistor and/or RF choke connected to the amplifier output lead... Question 327... Which of the following component package types have the least parasitic effects at frequencies above the HF range?... Answer 327... Surface mount... Question 328... What advantage does surface-mount technology offer at RF compared to using through-hole components?... Answer 328... Smaller circuit area... Answer 328... Shorter circuit board traces... Answer 328... Components have less parasitic inductance and capacitance... Answer 328... All these choices are correct... Question 329... What is a characteristic of DIP packaging used for integrated circuits?... Answer 329... Two rows of connecting pins on opposite sides of package (dual in-line package)... Question 330... Why are DIP through-hole package ICs not typically used at UHF and higher frequencies?... Answer 330... Excessive lead length... Question 331... What absorbs the energy from light falling on a photovoltaic cell?... Answer 331... Electrons... Question 332... What happens to photoconductive material when light shines on it?... Answer 332... Resistance decreases... Question 333... What is the most common configuration of an optoisolator or optocoupler?... Answer 333... An LED and a phototransistor... Question 334... What is the photovoltaic effect?... Answer 334... The conversion of light to electrical energy... Question 335... Which of the following describes an optical shaft encoder?... Answer 335... A device that detects rotation by interrupting a light source with a patterned wheel... Question 336... Which of these materials is most commonly used to create photoconductive devices?... Answer 336... Crystalline semiconductor... Question 337... What is a solid-state relay?... Answer 337... A device that uses semiconductors to implement the functions of an electromechanical relay... Question 338... Why are optoisolators often used in conjunction with solid-state circuits that control 120 VAC circuits?... Answer 338... Optoisolators provide an electrical isolation between a control circuit and the circuit being switched... Question 339... What is the efficiency of a photovoltaic cell?... Answer 339... The relative fraction of light that is converted to current... Question 340... What is the most common material used in power-generating photovoltaic cells?... Answer 340... Silicon... Question 341... What is the approximate open-circuit voltage produced by a fully illuminated silicon photovoltaic cell?... Answer 341... 0.5 volts... Question 342... Which circuit is bistable?... Answer 342... A flip-flop... Question 343... What is the function of a decade counter?... Answer 343... It produces one output pulse for every 10 input pulses... Question 344... Which of the following can divide the frequency of a pulse train by 2?... Answer 344... A flip-flop... Question 345... How many flip-flops are required to divide a signal frequency by 16?... Question 346... ... Answer 346... Which of the following circuits continuously alternates between two states without an external clock signal?... Answer 346... Astable multivibrator... Question 347... What is a characteristic of a monostable multivibrator?... Answer 347... It switches temporarily to an alternate state for a set time... Question 348... What logical operation does a NAND gate perform?... Answer 348... It produces a 0 at its output only if all inputs are 1... Question 349... What logical operation does an OR gate perform?... Answer 349... It produces a 1 at its output if any input is 1... Question 350... What logical operation is performed by a two-input exclusive NOR gate?... Answer 350... It produces a 0 at its output if one and only one of its inputs is 1... Question 351... What is a truth table?... Answer 351... A list of inputs and corresponding outputs for a digital device... Question 352... What does “positive logic” mean in reference to logic devices?... Answer 352... High voltage represents a 1, low voltage a 0... Question 353... For what portion of the signal cycle does each active element in a push-pull, Class AB amplifier conduct?... Answer 353... More than 180 degrees but less than 360 degrees... Question 354... What is a Class D amplifier?... Answer 354... An amplifier that uses switching technology to achieve high efficiency... Question 355... What circuit is required at the output of an RF switching amplifier?... Answer 355... A filter to remove harmonic content... Question 356... What is the operating point of a Class A common emitter amplifier?... Answer 356... Approximately halfway between saturation and cutoff... Question 357... What can be done to prevent unwanted oscillations in an RF power amplifier?... Answer 357... Install parasitic suppressors and/or neutralize the stage... Question 358... What is a characteristic of a grounded-grid amplifier?... Answer 358... Low input impedance... Question 359... Which of the following is the likely result of using a Class C amplifier to amplify a single-sideband phone signal?... Answer 359... Signal distortion and excessive bandwidth... Question 360... Why are switching amplifiers more efficient than linear amplifiers?... Answer 360... The switching device is at saturation or cutoff most of the time... Question 361... What is characteristic of an emitter follower (or common collector) amplifier?... Answer 361... Input and output signals in-phase... Question 362... How are the capacitors and inductors of a low-pass filter Pi-network arranged between the network’s input and output?... Answer 362... A capacitor is connected between the input and ground, another capacitor is connected between the output and ground, and an inductor is connected between the input and output... Question 363... What is the frequency response of a T-network with series capacitors and a shunt inductor?... Answer 363... High-pass... Question 364... What is the purpose of adding an inductor to a Pi-network to create a Pi-L-network?... Answer 364... Greater harmonic suppression... Question 365... How does an impedance-matching circuit transform a complex impedance to a resistive impedance?... Answer 365... It cancels the reactive part of the impedance and changes the resistive part to the desired value... Question 366... Which filter type has ripple in the passband and a sharp cutoff?... Answer 366... A Chebyshev filter... Question 367... What are the characteristics of an elliptical filter?... Answer 367... Extremely sharp cutoff with one or more notches in the stop band... Question 368... Which describes a Pi-L network?... Answer 368... A Pi-network with an additional output series inductor... Question 369... Which of the following is most frequently used as a band-pass or notch filter in VHF and UHF transceivers?... Answer 369... A helical filter... Question 370... What is a crystal lattice filter?... Answer 370... A filter for low-level signals made using quartz crystals... Question 371... Which of the following filters is used in a 2-meter band repeater duplexer?... Answer 371... A cavity filter... Question 372... Which of the following measures a filter’s ability to reject signals in adjacent channels?... Answer 372... Shape factor... Question 373... How does a linear electronic voltage regulator work?... Answer 373... The conduction of a control element is varied to maintain a constant output voltage... Question 374... How does a switchmode voltage regulator work?... Answer 374... By varying the duty cycle of pulses input to a filter... Question 375... What device is used as a stable voltage reference?... Answer 375... A Zener diode... Question 376... Which of the following describes a three-terminal voltage regulator?... Answer 376... A series regulator... Question 377... Which of the following types of linear voltage regulator operates by loading the unregulated voltage source?... Answer 377... A shunt regulator... Question 378... How is battery operating time calculated?... Answer 378... Capacity in amp-hours divided by average current... Question 379... Why is a switching type power supply less expensive and lighter than an equivalent linear power supply?... Answer 379... The high frequency inverter design uses much smaller transformers and filter components for an equivalent power output... Question 380... What is the purpose of an inverter connected to a solar panel output?... Answer 380... Convert the panel’s output from DC to AC... Question 381... What is the dropout voltage of a linear voltage regulator?... Answer 381... Minimum input-to-output voltage required to maintain regulation... Question 382... Which of the following calculates power dissipated by a series linear voltage regulator?... Answer 382... Voltage difference from input to output multiplied by output current... Question 383... What is the purpose of connecting equal-value resistors across power supply filter capacitors connected in series?... Answer 383... Equalize the voltage across each capacitor... Answer 383... Discharge the capacitors when voltage is removed... Answer 383... Provide a minimum load on the supply... Answer 383... All these choices are correct... Question 384... What is the purpose of a step-start circuit in a high-voltage power supply?... Answer 384... To allow the filter capacitors to charge gradually... Question 385... Which of the following can be used to generate FM phone signals?... Answer 385... Reactance modulation of a local oscillator... Question 386... What is the function of a reactance modulator?... Answer 386... Produce PM or FM signals by varying a capacitance... Question 387... What is a frequency discriminator?... Answer 387... A circuit for detecting FM signals... Question 388... What is one way to produce a single-sideband phone signal?... Answer 388... Use a balanced modulator followed by a filter... Question 389... What is added to an FM speech channel to boost the higher audio frequencies?... Answer 389... A pre-emphasis network... Question 390... Why is de-emphasis used in FM communications receivers?... Answer 390... For compatibility with transmitters using phase modulation... Question 391... What is meant by the term “baseband” in radio communications?... Answer 391... The frequency range occupied by a message signal prior to modulation... Question 392... What are the principal frequencies that appear at the output of a mixer?... Answer 392... The two input frequencies along with their sum and difference frequencies... Question 393... What occurs when the input signal levels to a mixer are too high?... Answer 393... Spurious mixer products are generated... Question 394... How does a diode envelope detector function?... Answer 394... By rectification and filtering of RF signals... Question 395... Which type of detector is used for demodulating SSB signals?... Answer 395... Product detector... Question 396... What is meant by “direct sampling” in software defined radios?... Answer 396... Incoming RF is digitized by an analog-to-digital converter without being mixed with a local oscillator signal... Question 397... What kind of digital signal processing audio filter is used to remove unwanted noise from a received SSB signal?... Answer 397... An adaptive filter... Question 398... What type of digital signal processing filter is used to generate an SSB signal?... Answer 398... A Hilbert-transform filter... Question 399... Which method generates an SSB signal using digital signal processing?... Answer 399... Signals are combined in quadrature phase relationship... Question 400... How frequently must an analog signal be sampled to be accurately reproduced?... Answer 400... At least twice the rate of the highest frequency component of the signal... Question 401... What is the minimum number of bits required to sample a signal with a range of 1 volt at a resolution of 1 millivolt?... Answer 401... 10 bits... Question 402... What function is performed by a Fast Fourier Transform?... Answer 402... Converting signals from the time domain to the frequency domain... Question 403... What is the function of decimation?... Answer 403... Reducing the effective sample rate by removing samples... Question 404... Why is an anti-aliasing filter required in a decimator?... Answer 404... It removes high-frequency signal components that would otherwise be reproduced as lower frequency components... Question 405... What aspect of receiver analog-to-digital conversion determines the maximum receive bandwidth of a direct-sampling software defined radio (SDR)?... Answer 405... Sample rate... Question 406... What sets the minimum detectable signal level for a direct-sampling software defined receiver in the absence of atmospheric or thermal noise?... Answer 406... Reference voltage level and sample width in bits... Question 407... Which of the following is generally true of Finite Impulse Response (FIR) filters?... Answer 407... FIR filters can delay all frequency components of the signal by the same amount... Question 408... What is the function of taps in a digital signal processing filter?... Answer 408... Provide incremental signal delays for filter algorithms... Question 409... Which of the following would allow a digital signal processing filter to create a sharper filter response?... Answer 409... More taps... Question 410... What is the typical output impedance of an op-amp?... Answer 410... Very low... Question 411... What is the typical input impedance of an op-amp?... Answer 411... Very high... Question 412... What is meant by the term “op-amp input offset voltage”?... Answer 412... The differential input voltage needed to bring the open loop output voltage to zero... Question 413... How can unwanted ringing and audio instability be prevented in an op-amp audio filter?... Answer 413... Restrict both gain and Q... Question 414... What is the gain-bandwidth of an operational amplifier?... Answer 414... The frequency at which the open-loop gain of the amplifier equals one... Question 415... What is the frequency response of the circuit in E7-3 if a capacitor is added across the feedback resistor?... Answer 415... Low-pass filter... Question 416... How does the gain of an ideal operational amplifier vary with frequency?... Answer 416... It does not vary with frequency... Question 417... What is an operational amplifier?... Answer 417... A high-gain, direct-coupled differential amplifier with very high input impedance and very low output impedance... Question 418... What are three common oscillator circuits?... Answer 418... Colpitts, Hartley, and Pierce... Question 419... What is a microphonic?... Answer 419... Changes in oscillator frequency caused by mechanical vibration... Question 420... What is a phase-locked loop?... Answer 420... An electronic servo loop consisting of a phase detector, a low-pass filter, a voltage-controlled oscillator, and a stable reference oscillator... Question 421... How is positive feedback supplied in a Colpitts oscillator?... Answer 421... Through a capacitive divider... Question 422... How is positive feedback supplied in a Pierce oscillator?... Answer 422... Through a quartz crystal... Question 423... Which of these functions can be performed by a phase-locked loop?... Answer 423... Frequency synthesis and FM demodulation... Question 424... How can an oscillator’s microphonic responses be reduced?... Answer 424... Mechanically isolate the oscillator circuitry from its enclosure... Question 425... Which of the following components can be used to reduce thermal drift in crystal oscillators?... Answer 425... NP0 capacitors... Question 426... What type of frequency synthesizer circuit uses a phase accumulator, lookup table, digital-to-analog converter, and a low-pass anti-alias filter?... Answer 426... A direct digital synthesizer... Question 427... What information is contained in the lookup table of a direct digital synthesizer (DDS)?... Answer 427... Amplitude values that represent the desired waveform... Question 428... What are the major spectral impurity components of direct digital synthesizers?... Answer 428... Spurious signals at discrete frequencies... Question 429... Which of the following ensures that a crystal oscillator operates on the frequency specified by the crystal manufacturer?... Answer 429... Provide the crystal with a specified parallel capacitance... Question 430... Which of the following is a technique for providing highly accurate and stable oscillators needed for microwave transmission and reception?... Answer 430... Use a GPS signal reference... Answer 430... Use a rubidium stabilized reference oscillator... Answer 430... Use a temperature-controlled high Q dielectric resonator... Answer 430... All these choices are correct... Question 431... What technique shows that a square wave is made up of a sine wave and its odd harmonics?... Answer 431... Fourier analysis... Question 432... Which of the following is a type of analog-to-digital conversion?... Answer 432... Successive approximation... Question 433... Which of the following describes a signal in the time domain?... Answer 433... Amplitude at different times... Question 434... What is “dither” with respect to analog-to-digital converters?... Answer 434... A small amount of noise added to the input signal to reduce quantization noise... Question 435... What is the benefit of making voltage measurements with a true-RMS calculating meter?... Answer 435... RMS is measured for both sinusoidal and non-sinusoidal signals... Question 436... What is the approximate ratio of PEP-to-average power in an unprocessed single-sideband phone signal?... Answer 436... 2.5 to 1... Question 437... What determines the PEP-to-average power ratio of an unprocessed single-sideband phone signal?... Answer 437... Speech characteristics... Question 438... Why are direct or flash conversion analog-to-digital converters used for a software defined radio?... Answer 438... Very high speed allows digitizing high frequencies... Question 439... How many different input levels can be encoded by an analog-to-digital converter with 8-bit resolution?... Answer 439... 256... Question 440... What is the purpose of a low-pass filter used at the output of a digital-to-analog converter?... Answer 440... Remove spurious sampling artifacts from the output signal... Question 441... Which of the following is a measure of the quality of an analog-to-digital converter?... Answer 441... Total harmonic distortion... Question 442... What is the modulation index of an FM signal?... Answer 442... The ratio of frequency deviation to modulating signal frequency... Question 443... How does the modulation index of a phase-modulated emission vary with RF carrier frequency?... Answer 443... It does not depend on the RF carrier frequency... Question 444... What is the modulation index of an FM phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency if the highest modulating frequency is 1000 Hz?... Question 445... ... Answer 445... What is the modulation index of an FM phone signal having a maximum carrier deviation of plus or minus 6 kHz if the highest modulating frequency is 2 kHz?... Question 446... ... Answer 446... What is the deviation ratio of an FM phone signal having a maximum frequency swing of plus or minus 5 kHz if the highest modulation frequency is 3 kHz?... Answer 446... 1.67... Question 447... What is the deviation ratio of an FM phone signal having a maximum frequency swing of plus or minus 7.5 kHz if the highest modulation frequency is 3.5 kHz?... Answer 447... 2.14... Question 448... Orthogonal frequency-division multiplexing (OFDM) is a technique used for which types of amateur communication?... Answer 448... Digital modes... Question 449... What describes orthogonal frequency-division multiplexing (OFDM)?... Answer 449... A digital modulation technique using subcarriers at frequencies chosen to avoid intersymbol interference... Question 450... What is deviation ratio?... Answer 450... The ratio of the maximum carrier frequency deviation to the highest audio modulating frequency... Question 451... What is frequency division multiplexing (FDM)?... Answer 451... Dividing the transmitted signal into separate frequency bands that each carry a different data stream... Question 452... What is digital time division multiplexing?... Answer 452... Two or more signals are arranged to share discrete time slots of a data transmission... Question 453... What is Quadrature Amplitude Modulation or QAM?... Answer 453... Transmission of data by modulating the amplitude of two carriers of the same frequency but 90 degrees out of phase... Question 454... What is the definition of symbol rate in a digital transmission?... Answer 454... The rate at which the waveform changes to convey information... Question 455... Why should the phase of a PSK signal be changed at the zero crossing of the RF signal?... Answer 455... To minimize bandwidth... Question 456... What technique minimizes the bandwidth of a PSK31 signal?... Answer 456... Use of sinusoidal data pulses... Question 457... What is the approximate bandwidth of a 13-WPM International Morse Code transmission?... Answer 457... 52 Hz... Question 458... What is the bandwidth of an FT8 signal?... Answer 458... 50 Hz... Question 459... What is the bandwidth of a 4,800-Hz frequency shift, 9,600-baud ASCII FM transmission?... Answer 459... 15.36 kHz... Question 460... How does ARQ accomplish error correction?... Answer 460... If errors are detected, a retransmission is requested... Question 461... Which digital code allows only one bit to change between sequential code values?... Answer 461... Gray code... Question 462... How can data rate be increased without increasing bandwidth?... Answer 462... Using a more efficient digital code... Question 463... What is the relationship between symbol rate and baud?... Answer 463... They are the same... Question 464... What factors affect the bandwidth of a transmitted CW signal?... Answer 464... Keying speed and shape factor (rise and fall time)... Question 465... What is described by the constellation diagram of a QAM or QPSK signal?... Answer 465... The possible phase and amplitude states for each symbol... Question 466... What type of addresses do nodes have in a mesh network?... Answer 466... Internet Protocol (IP)... Question 467... What technique do individual nodes use to form a mesh network?... Answer 467... Discovery and link establishment protocols... Question 468... Why are received spread spectrum signals resistant to interference?... Answer 468... Signals not using the spread spectrum algorithm are suppressed in the receiver... Question 469... What spread spectrum communications technique uses a high-speed binary bit stream to shift the phase of an RF carrier?... Answer 469... Direct sequence... Question 470... Which describes spread spectrum frequency hopping?... Answer 470... Rapidly varying the frequency of a transmitted signal according to a pseudorandom sequence... Question 471... What is the primary effect of extremely short rise or fall time on a CW signal?... Answer 471... The generation of key clicks... Question 472... What is the most common method of reducing key clicks?... Answer 472... Increase keying waveform rise and fall times... Question 473... What is the advantage of including parity bits in ASCII characters?... Answer 473... Some types of errors can be detected... Question 474... What is a common cause of overmodulation of AFSK signals?... Answer 474... Excessive transmit audio levels... Question 475... What parameter evaluates distortion of an AFSK signal caused by excessive input audio levels?... Answer 475... Intermodulation Distortion (IMD)... Question 476... What is considered an acceptable maximum IMD level for an idling PSK signal?... Answer 476... -30 dB... Question 477... What are some of the differences between the Baudot digital code and ASCII?... Answer 477... Baudot uses 5 data bits per character, ASCII uses 7 or 8; Baudot uses 2 characters as letters/figures shift codes, ASCII has no letters/figures shift code... Question 478... What is one advantage of using ASCII code for data communications?... Answer 478... It is possible to transmit both uppercase and lowercase text... Question 479... What is an isotropic radiator?... Answer 479... A hypothetical, lossless antenna having equal radiation intensity in all directions used as a reference for antenna gain... Question 480... What is the effective radiated power (ERP) of a repeater station with 150 watts transmitter power output, 2 dB feed line loss, 2.2 dB duplexer loss, and 7 dBd antenna gain?... Answer 480... 286 watts... Question 481... What term describing total radiated power takes into account all gains and losses?... Answer 481... Effective radiated power... Question 482... Which of the following factors affect the feed point impedance of an antenna?... Answer 482... Antenna height... Question 483... What does the term “ground gain” mean?... Answer 483... An increase in signal strength from ground reflections in the environment of the antenna... Question 484... What is the effective radiated power (ERP) of a repeater station with 200 watts transmitter power output, 4 dB feed line loss, 3.2 dB duplexer loss, 0.8 dB circulator loss, and 10 dBd antenna gain?... Answer 484... 317 watts... Question 485... What is the effective isotropic radiated power (EIRP) of a repeater station with 200 watts transmitter power output, 2 dB feed line loss, 2.8 dB duplexer loss, 1.2 dB circulator loss, and 7 dBi antenna gain?... Answer 485... 252 watts... Question 486... Which frequency band has the smallest first Fresnel zone?... Answer 486... 5.8 GHz... Question 487... What is antenna efficiency?... Answer 487... Radiation resistance divided by total resistance... Question 488... Which of the following improves the efficiency of a ground-mounted quarter-wave vertical antenna?... Answer 488... Installing a ground radial system... Question 489... Which of the following determines ground losses for a ground-mounted vertical antenna operating on HF?... Answer 489... Soil conductivity... Question 490... How much gain does an antenna have compared to a half-wavelength dipole if it has 6 dB gain over an isotropic radiator?... Answer 490... 3.85 dB... Question 491... What is the difference in radiated power between a lossless antenna with gain and an isotropic radiator driven by the same power?... Answer 491... They are the same... Question 492... What is the far field of an antenna?... Answer 492... The region where the shape of the radiation pattern no longer varies with distance... Question 493... What type of analysis is commonly used for modeling antennas?... Answer 493... Method of Moments... Question 494... What is the principle of a Method of Moments analysis?... Answer 494... A wire is modeled as a series of segments, each having a uniform value of current... Question 495... What is a disadvantage of decreasing the number of wire segments in an antenna model below 10 segments per half-wavelength?... Answer 495... The computed feed point impedance may be incorrect... Question 496... What type of radiation pattern is created by two 1/4-wavelength vertical antennas spaced 1/2-wavelength apart and fed 180 degrees out of phase?... Answer 496... A figure-eight oriented along the axis of the array... Question 497... What type of radiation pattern is created by two 1/4-wavelength vertical antennas spaced 1/4-wavelength apart and fed 90 degrees out of phase?... Answer 497... Cardioid... Question 498... What type of radiation pattern is created by two 1/4-wavelength vertical antennas spaced 1/2-wavelength apart and fed in phase?... Answer 498... A figure-eight broadside to the axis of the array... Question 499... What happens to the radiation pattern of an unterminated long wire antenna as the wire length is increased?... Answer 499... Additional lobes form with major lobes increasingly aligned with the axis of the antenna... Question 500... What is the purpose of feeding an off-center-fed dipole (OCFD) between the center and one end instead of at the midpoint?... Answer 500... To create a similar feed point impedance on multiple bands... Question 501... What is the effect of adding a terminating resistor to a rhombic or long-wire antenna?... Answer 501... It changes the radiation pattern from bidirectional to unidirectional... Question 502... What is the approximate feed point impedance at the center of a two-wire half-wave folded dipole antenna?... Answer 502... 300 ohms... Question 503... What is a folded dipole antenna?... Answer 503... A half-wave dipole with an additional parallel wire connecting its two ends... Question 504... Which of the following describes a G5RV antenna?... Answer 504... A wire antenna center-fed through a specific length of open-wire line connected to a balun and coaxial feed line... Question 505... Which of the following describes a Zepp antenna?... Answer 505... An end-fed half-wavelength dipole... Question 506... How is the far-field elevation pattern of a vertically polarized antenna affected by being mounted over seawater versus soil?... Answer 506... Radiation at low angles increases... Question 507... Which of the following describes an extended double Zepp antenna?... Answer 507... A center-fed 1.25-wavelength dipole antenna... Question 508... How does the radiation pattern of a horizontally polarized antenna vary with increasing height above ground?... Answer 508... The takeoff angle of the lowest elevation lobe decreases... Question 509... How does the radiation pattern of a horizontally-polarized antenna mounted above a long slope compare with the same antenna mounted above flat ground?... Answer 509... The main lobe takeoff angle decreases in the downhill direction... Question 510... How much does the gain of an ideal parabolic reflector antenna increase when the operating frequency is doubled?... Answer 510... 6 dB... Question 511... How can two linearly polarized Yagi antennas be used to produce circular polarization?... Answer 511... 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... Question 512... What is the most efficient location for a loading coil on an electrically short whip?... Answer 512... Near the center of the vertical radiator... Question 513... Why should antenna loading coils have a high ratio of reactance to resistance?... Answer 513... To maximize efficiency... Question 514... Approximately how long is a Yagi’s driven element?... Answer 514... 1/2 wavelength... Question 515... What happens to SWR bandwidth when one or more loading coils are used to resonate an electrically short antenna?... Answer 515... It is decreased... Question 516... What is an advantage of top loading an electrically short HF vertical antenna?... Answer 516... Improved radiation efficiency... Question 517... What happens as the Q of an antenna increases?... Answer 517... SWR bandwidth decreases... Question 518... What is the function of a loading coil in an electrically short antenna?... Answer 518... To resonate the antenna by cancelling the capacitive reactance... Question 519... How does radiation resistance of a base-fed whip antenna change below its resonant frequency?... Answer 519... Radiation resistance decreases... Question 520... Why do most two-element Yagis with normal spacing have a reflector instead of a director?... Answer 520... Higher gain... Question 521... What is the purpose of making a Yagi’s parasitic elements either longer or shorter than resonance?... Answer 521... Control of phase shift... Question 522... Which matching system for Yagi antennas requires the driven element to be insulated from the boom?... Answer 522... Beta or hairpin... Question 523... 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?... Answer 523... Gamma match... Question 524... What matching system uses a short length of transmission line connected in parallel with the feed line at or near the feed point?... Answer 524... Stub match... Question 525... What is the purpose of the series capacitor in a gamma match?... Answer 525... To cancel unwanted inductive reactance... Question 526... What Yagi driven element feed point impedance is required to use a beta or hairpin matching system?... Answer 526... Capacitive (driven element electrically shorter than 1/2 wavelength)... Question 527... Which of these transmission line impedances would be suitable for constructing a quarter-wave Q-section for matching a 100-ohm feed point impedance to a 50-ohm transmission line?... Answer 527... 75 ohms... Question 528... What parameter describes the interaction of a load and transmission line?... Answer 528... Reflection coefficient... Question 529... What is a use for a Wilkinson divider?... Answer 529... To divide power equally between two 50-ohm loads while maintaining 50-ohm input impedance... Question 530... Which of the following is used to shunt feed a grounded tower at its base?... Answer 530... Gamma match... Question 531... What is the purpose of using multiple driven elements connected through phasing lines?... Answer 531... To control the antenna’s radiation pattern... Question 532... What is the velocity factor of a transmission line?... Answer 532... The velocity of a wave in the transmission line divided by the velocity of light in a vacuum... Question 533... Which of the following has the biggest effect on the velocity factor of a transmission line?... Answer 533... The insulating dielectric material... Question 534... Why is the electrical length of a coaxial cable longer than its physical length?... Answer 534... Electromagnetic waves move more slowly in a coaxial cable than in air... Question 535... What impedance does a 1/2-wavelength transmission line present to an RF generator when the line is shorted at the far end?... Answer 535... Very low impedance... Question 536... What is microstrip?... Answer 536... Precision printed circuit conductors above a ground plane that provide constant impedance interconnects at microwave frequencies... Question 537... What is the approximate physical length of an air-insulated, parallel conductor transmission line that is electrically 1/2 wavelength long at 14.10 MHz?... Answer 537... 10.6 meters... Question 538... How does parallel conductor transmission line compare to coaxial cable with a plastic dielectric?... Answer 538... Lower loss... Question 539... Which of the following is a significant difference between foam dielectric coaxial cable and solid dielectric coaxial cable, assuming all other parameters are the same?... Answer 539... Foam dielectric coaxial cable has lower safe maximum operating voltage... Answer 539... Foam dielectric coaxial cable has lower loss per unit of length... Answer 539... Foam dielectric coaxial cable has higher velocity factor... Answer 539... All these choices are correct... Question 540... What impedance does a 1/4-wavelength transmission line present to an RF generator when the line is shorted at the far end?... Answer 540... Very high impedance... Question 541... What impedance does a 1/8-wavelength transmission line present to an RF generator when the line is shorted at the far end?... Answer 541... An inductive reactance... Question 542... What impedance does a 1/8-wavelength transmission line present to an RF generator when the line is open at the far end?... Answer 542... A capacitive reactance... Question 543... What impedance does a 1/4-wavelength transmission line present to an RF generator when the line is open at the far end?... Answer 543... Very low impedance... Question 544... Which of the following can be calculated using a Smith chart?... Answer 544... Impedance along transmission lines... Question 545... What type of coordinate system is used in a Smith chart?... Answer 545... Resistance circles and reactance arcs... Question 546... Which of the following is often determined using a Smith chart?... Answer 546... Impedance and SWR values in transmission lines... Question 547... What are the two families of circles and arcs that make up a Smith chart?... Answer 547... Resistance and reactance... Question 548... Which of the following is a common use for a Smith chart?... Answer 548... Determine the length and position of an impedance matching stub... Question 549... How is a Smith chart normalized?... Answer 549... Reassign the prime center’s impedance value... Question 550... What third family of circles is often added to a Smith chart during the process of designing impedance matching networks?... Answer 550... Constant-SWR circles... Question 551... What do the arcs on a Smith chart represent?... Answer 551... Points with constant reactance... Question 552... In what units are the wavelength scales on a Smith chart calibrated?... Answer 552... In fractions of transmission line electrical wavelength... Question 553... When constructing a Beverage antenna, which of the following factors should be included in the design to achieve good performance at the desired frequency?... Answer 553... It should be at least one wavelength long... Question 554... Which is generally true for 160- and 80-meter receiving antennas?... Answer 554... Atmospheric noise is so high that directivity is much more important than losses... Question 555... What is receiving directivity factor (RDF)?... Answer 555... Peak antenna gain compared to average gain over the hemisphere around and above the antenna... Question 556... What is the purpose of placing an electrostatic shield around a small-loop direction-finding antenna?... Answer 556... It eliminates unbalanced capacitive coupling to the antenna’s surroundings, improving the depth of its nulls... Question 557... What challenge is presented by a small wire-loop antenna for direction finding?... Answer 557... It has a bidirectional null pattern... Question 558... What indicates the correct value of terminating resistance for a Beverage antenna?... Answer 558... Minimum variation in SWR over the desired frequency range... Question 559... What is the function of a Beverage antenna’s termination resistor?... Answer 559... Absorb signals from the reverse direction... Question 560... What is the function of a sense antenna?... Answer 560... It modifies the pattern of a DF antenna to provide a null in only one direction... Question 561... What type of radiation pattern is created by a single-turn, terminated loop such as a pennant antenna?... Answer 561... Cardioid... Question 562... How can the output voltage of a multiple-turn receiving loop antenna be increased?... Answer 562... By increasing the number of turns and/or the area enclosed by the loop... Question 563... What feature of a cardioid pattern antenna makes it useful for direction-finding antennas?... Answer 563... A single null... Question 564... What is the primary function of an external earth connection or ground rod?... Answer 564... Lightning charge dissipation... Question 565... When evaluating RF exposure levels from your station at a neighbor’s home, what must you do?... Answer 565... Ensure signals from your station are less than the uncontrolled maximum permissible exposure (MPE) limits... Question 566... Over what range of frequencies are the FCC human body RF exposure limits most restrictive?... Answer 566... 30 - 300 MHz... Question 567... When evaluating a site with multiple transmitters operating at the same time, the operators and licensees of which transmitters are responsible for mitigating over-exposure situations?... Answer 567... Each transmitter that produces 5 percent or more of its MPE limit in areas where the total MPE limit is exceeded... Question 568... What hazard is created by operating at microwave frequencies?... Answer 568... The high gain antennas commonly used can result in high exposure levels... Question 569... Why are there separate electric (E) and magnetic (H) MPE limits at frequencies below 300 MHz?... Answer 569... The body reacts to electromagnetic radiation from both the E and H fields... Answer 569... Ground reflections and scattering cause the field strength to vary with location... Answer 569... E field and H field radiation intensity peaks can occur at different locations... Answer 569... All these choices are correct... Question 570... What is meant by “100% tie-off” regarding tower safety?... Answer 570... At least one lanyard attached to the tower at all times... Question 571... What does SAR measure?... Answer 571... The rate at which RF energy is absorbed by the body... Question 572... Which of the following types of equipment are exempt from RF exposure evaluations?... Answer 572... Hand-held transceivers sold before May 3, 2021... Question 573... When must an RF exposure evaluation be performed on an amateur station operating on 80 meters?... Answer 573... An evaluation must always be performed... Question 574... To what should lanyards be attached while climbing?... Answer 574... Tower legs... Question 575... Where should a shock-absorbing lanyard be attached to a tower when working above ground?... Answer 575... Above the climber’s head level...