B-003 — Station assembly, practice and safety

Building a station safely: power supplies, grounding, RF exposure, lightning, feedline routing, and what a transmitter, receiver and transceiver actually do.

All 199 questions

• B-003-001-001 To be most effective, where should a low-pass filter be connected in an HF station without an external power amplifier?
• B-003-001-002 In an HF station that includes an external RF power amplifier, where should a low-pass filter be located?
• B-003-001-003 Why do modern HF transmitters have a built-in low-pass filter in their RF output circuits?
• B-003-001-004 Which component in an HF station is used to determine if the antenna system impedance is matched to the transmitter?
• B-003-001-005 What is the purpose of the antenna switch in an HF station?
• B-003-001-006 In an HF station, what device might allow the use of an antenna on a band it was not designed for?
• B-003-001-007 In an HF station, which component is designed to dissipate RF energy and prevent radiation?
• B-003-001-008 In an HF station, right after which component is the SWR meter inserted?
• B-003-001-009 When using an HF transmitter with a solid-state final amplifier, which station component may need to be adjusted when changing frequency?
• B-003-002-001 What does the microphone produce in an FM transmitter?
• B-003-002-002 The microphone of an FM transmitter:
• B-003-002-003 An FM transmitter's modulator:
• B-003-002-004 How is the oscillator in the FM transmitter different from oscillators in AM, CW, and SSB transmitters?
• B-003-002-005 In an FM transmitter, the frequency multiplier:
• B-003-002-006 In an FM transmitter, which stage produces a useful harmonic?
• B-003-002-007 In an FM transmitter, which stage draws the most electric power?
• B-003-003-001 In a superheterodyne receiver, which stage is called the front-end?
• B-003-003-002 In a VHF superheterodyne receiver, which stage must be designed to produce very little noise?
• B-003-003-003 In a superheterodyne receiver, which stage allows detection to function at a single frequency regardless of the received frequency?
• B-003-003-004 In a superheterodyne receiver, which stage sets the received frequency?
• B-003-003-005 In a superheterodyne receiver, which stage rejects signals on adjacent channels?
• B-003-003-006 In a superheterodyne receiver, which stage provides the final signal power to drive the detector?
• B-003-003-007 In an FM receiver, what is the purpose of the limiter?
• B-003-003-008 In an FM receiver, what is the purpose of the discriminator?
• B-003-003-009 In a receiver, which stage is controlled by the volume control?
• B-003-003-010 In an FM receiver, which stage includes a squelch circuit?
• B-003-004-001 In a basic CW transmitter, the output from the oscillator is:
• B-003-004-002 In a basic CW transmitter, what type of electricity directly powers each stage?
• B-003-004-003 In a basic CW transmitter, why is the oscillator followed by a driver/buffer stage?
• B-003-004-004 In a basic three-stage CW transmitter, what does the key do?
• B-003-004-005 In a basic CW transmitter, what does the power amplifier stage do?
• B-003-004-006 In a basic CW transmitter, what does the key do?
• B-003-005-001 In an SSB/CW receiver, what is the purpose of the antenna?
• B-003-005-002 In an SSB/CW receiver, what is the purpose of the radio frequency (RF) amplifier?
• B-003-005-003 In an SSB/CW receiver, what is the purpose of the mixer?
• B-003-005-004 In an SSB/CW receiver, what is the purpose of the signal generated by the local oscillator?
• B-003-005-005 In an SSB/CW receiver, what is the purpose of the intermediate frequency (IF) filter?
• B-003-005-006 In an SSB/CW receiver, what is the purpose of the intermediate frequency (IF) amplifier?
• B-003-005-007 In an SSB/CW receiver, what is the purpose of the product detector?
• B-003-005-008 In an SSB/CW receiver, what is the purpose of the signal produced by the beat frequency oscillator (BFO)?
• B-003-005-009 In an SSB/CW receiver, what is the purpose of the audio frequency (AF) amplifier?
• B-003-005-010 In an SSB/CW receiver, which stage could include an audio band-pass filter?
• B-003-006-001 In a single-sideband transmitter, what does the fixed RF oscillator do?
• B-003-006-002 In a single-sideband transmitter, why is the speech amplifier needed?
• B-003-006-003 In a typical single-sideband transmitter, what is the purpose of the filter that follows the balanced modulator?
• B-003-006-004 In a typical single-sideband transmitter, at what frequency is the sideband filter tuned?
• B-003-006-005 In a single-sideband transmitter, what is the purpose of the speech amplifier?
• B-003-006-006 In a single-sideband transmitter, which stage transposes the single-sideband signal to the operating frequency?
• B-003-006-007 In a single-sideband transmitter, which stage allows you to adjust the final transmit frequency?
• B-003-006-008 In a single-sideband transmitter, which stage normally includes a circuit providing protection from excessive SWR?
• B-003-006-009 In a single-sideband transmitter, which stage transposes the voice message from the audio spectrum to the radio spectrum?
• B-003-007-001 Which of the following is a function of the sound card interface in a station operating computer-based digital modes?
• B-003-007-002 Which of the following is a function of the sound card interface in a station operating computer-based digital modes?
• B-003-007-003 Which of the following is one function of most sound card interfaces in a station operating computer-based digital modes?
• B-003-007-004 Which of the following is a function of the sound card interface in a station operating computer-based digital modes?
• B-003-007-005 Why are isolation transformers often included in the sound card interface of a station operating computer-based digital modes?
• B-003-007-006 Why are some transceivers capable of operating computer-based digital modes without a separate sound card?
• B-003-008-001 If a linear power supply provides overvoltage protection, where is the voltage monitored?
• B-003-008-002 What is the purpose of the transformer in a linear power supply?
• B-003-008-003 What is the purpose of the rectifier in a linear power supply?
• B-003-008-004 What is the purpose of the filter in a linear power supply?
• B-003-008-005 What is the purpose of the regulator in a linear power supply?
• B-003-008-006 In a linear power supply, which stage typically requires a heat sink?
• B-003-009-001 Which component of a 3-element Yagi antenna is primarily for mechanical support?
• B-003-009-002 In a 3-element Yagi antenna, what is the longest radiating element?
• B-003-009-003 In a 3-element Yagi antenna, which is the shortest radiating element?
• B-003-009-004 In a 3-element Yagi antenna, which element is connected to the transmission line?
• B-003-010-001 Which series of emission modes listed below is in order from the narrowest bandwidth to the widest bandwidth?
• B-003-010-002 The figure in a receiver's specifications which indicates its sensitivity is the:
• B-003-010-003 What are the two signal parameters presented to the user on the waterfall display (spectrogram) of a modern receiver?
• B-003-010-004 What is the function of automatic gain control (AGC) in a receiver?
• B-003-010-005 For which of the following emission modes is it important for the receiver to be tuned accurately (within 100 Hz)?
• B-003-010-006 A superheterodyne receiver has an intermediate frequency (IF) of 455 kHz. The local oscillator runs above the operating frequency. To which frequency should it be tuned to receive a signal on 3.54 MHz?
• B-003-010-007 When receiving a modulated signal, what is the adverse consequence of too narrow a receiver bandwidth?
• B-003-010-008 Apart from sensitivity and selectivity, which of these is the third main indicator of communications receiver performance?
• B-003-010-009 A communications receiver has four filters installed in it, respectively designated as 250 Hz, 500 Hz, 2.4 kHz, and 6 kHz. If you were listening to single sideband, which filter would you utilize?
• B-003-010-010 A communications receiver has four filters installed in it, respectively designated as 250 Hz, 500 Hz, 2.4 kHz and 6 kHz. You are copying a CW transmission and there is a great deal of interference. Which one of the filters would you choose?
• B-003-010-011 When receiving CW, which of these frequency ranges is optimum for a band-pass filter?
• B-003-011-001 What does chirp mean?
• B-003-011-002 What can be done to keep a CW transmitter from chirping?
• B-003-011-003 What is the advantage of using a variable frequency oscillator in a basic CW transmitter?
• B-003-011-004 Which type of transmitter modulation changes the amplitude of an RF wave for the purpose of conveying information?
• B-003-011-005 In what emission mode does the instantaneous amplitude (envelope) of the RF signal vary with the modulating audio?
• B-003-011-006 Morse code is usually transmitted by radio as:
• B-003-011-007 You are transmitting using amplitude modulation. What bandwidth does your signal occupy if the highest frequency of your voice is 3 kHz?
• B-003-011-008 What frequency components are present in the bandwidth of an amplitude modulated signal?
• B-003-011-009 An RF oscillator should be electrically and mechanically stable. This is to ensure that the oscillator does NOT:
• B-003-011-010 The DC power to the final stage of your transmitter is 200 watts and the RF output is 125 watts. What has happened to the rest of the power?
• B-003-011-011 The difference between DC input power and RF output power of a transmitter RF amplifier:
• B-003-012-001 What may happen if an SSB transmitter is operated with the microphone gain set too high?
• B-003-012-002 What may happen if an SSB transmitter is operated with too much speech processing?
• B-003-012-003 What is the term for the average power during one RF cycle, at the crest of the modulation envelope?
• B-003-012-004 What is the usual bandwidth of an amateur radio single-sideband signal?
• B-003-012-005 Why does the power amplifier of the SSB transmitter need to be linear?
• B-003-012-006 What is one advantage of carrier suppression in a double sideband voice transmission?
• B-003-012-007 What does overmodulation do to a single-sideband signal?
• B-003-012-008 How should the microphone gain control be adjusted for voice operation on a single-sideband transmitter?
• B-003-012-009 The purpose of a balanced modulator in an SSB transmitter is to:
• B-003-012-010 Your SSB transmitter is set to operate lower sideband at 7100 kHz. With a single 1000 Hz tone as modulation, at which frequency is RF transmitted?
• B-003-012-011 The automatic level control (ALC) in an SSB transmitter:
• B-003-013-001 What causes the loud noise heard from an FM receiver in the absence of a signal?
• B-003-013-002 You are using an FM repeater configured for 5 kHz deviation, but your transmitter is set to 2.5 kHz deviation. What is the consequence?
• B-003-013-003 What term defines the change in frequency caused by modulation in an FM transmitter?
• B-003-013-004 What kind of emission would your FM transmitter produce if its microphone failed to work?
• B-003-013-005 Why is FM voice best for local VHF/UHF radio communications?
• B-003-013-006 What is the approximate bandwidth of a frequency modulated signal using 5 kHz deviation?
• B-003-013-007 How is a higher level of the modulating signal represented in an FM signal?
• B-003-013-008 What modulation method is most closely related to frequency modulation?
• B-003-013-009 Why isn't FM used as an amateur radio emission mode below 28 MHz?
• B-003-013-010 Several stations report that your FM transmission is loud and distorted, but on frequency. Which of the following is the most probable cause of the distortion?
• B-003-013-011 When more than one signal is present, the FM receiver is likely to demodulate only the strongest signal. What is this behaviour called?
• B-003-014-001 What do many amateur radio operators use to help form good Morse code characters?
• B-003-014-002 How does an electronic keyer help form good Morse code characters?
• B-003-014-003 What do you need to adjust before using a microphone for the first time with a transceiver?
• B-003-014-004 What noise management system analyzes noise and signal characteristics to partially remove noise?
• B-003-014-005 What circuit causes a transmitter to automatically transmit when an operator speaks into its microphone?
• B-003-014-006 What is the reason for using a properly adjusted speech processor with a single-sideband voice transmitter?
• B-003-014-007 If a single-sideband voice transmitter is 100% modulated, how will using a speech processor affect the transmitter's output?
• B-003-014-008 In a receiver, what noise management circuit recognizes high-amplitude short-duration pulses and removes them?
• B-003-014-009 What type of interference is a noise blanker circuit most effective in eliminating?
• B-003-014-010 What is the function of transmit/receive switching in a transceiver?
• B-003-014-011 What type of microphone has internal components similar to a loudspeaker?
• B-003-015-001 Why can a modern digital radio system transmit voice and images, not just data?
• B-003-015-002 What is the fundamental difference between digital and analog data?
• B-003-015-003 What is the function of a digipeater?
• B-003-015-004 What does "network" mean in packet radio?
• B-003-015-005 Why can dozens of FT8 communications occur simultaneously in the space needed for one single-sideband transmission?
• B-003-015-006 Which of these modes can work at the lowest signal-to-noise ratio as measured in a 2500 Hz bandwidth?
• B-003-015-007 When selecting an RTTY transmitting frequency, what minimum frequency separation from a contact in progress should you allow (centre to centre) to minimize interference?
• B-003-015-008 When using a digital mode based on a computer sound card, how can you verify that the transmit audio level is NOT excessive?
• B-003-015-009 What feature of packet radio makes it especially useful for emergency communications?
• B-003-015-010 A digital protocol implements automatic repeat request (ARQ). What does it permit?
• B-003-015-011 With a digital communication mode based on a computer sound card, what is the result of feeding excessive audio into the transmitter?
• B-003-016-001 What approximate voltage does a standard automobile starter battery usually supply?
• B-003-016-002 Which of the following has a positive terminal and a negative terminal?
• B-003-016-003 A battery, that can be repeatedly recharged by supplying it with electrical energy, is known as a:
• B-003-016-004 Which of the following is a source of electromotive force (EMF)?
• B-003-016-005 Why is the NiMH battery often preferred over a conventional alkaline battery?
• B-003-016-006 The voltage at a battery's terminals will drop when it supplies current. What is the cause of the drop?
• B-003-016-007 For portable operation, what is the primary advantage of lithium-based batteries over lead-acid batteries?
• B-003-016-008 Battery capacity is commonly stated as a value of current delivered over a specified period of time. What is the effect of exceeding that specified current?
• B-003-016-009 What voltage and capacity will you achieve by connecting two 12 volts, 20 ampere-hour batteries in parallel?
• B-003-016-010 What voltage and capacity will you achieve by connecting two 12 volts, 20 ampere-hour batteries in series?
• B-003-016-011 A lithium-ion battery should never be:
• B-003-017-001 You construct a simple DC power supply using a transformer, rectifier and filter capacitor. If you use the supply to power a CW transmitter, what problem with signal quality could it cause?
• B-003-017-002 What device converts 120 volts AC to 12 volts DC?
• B-003-017-003 When selecting a 13.8 V DC power supply for a transceiver, what design specification is most important?
• B-003-017-004 Compared to a switching (switch mode) power supply, why may a linear power supply be preferred?
• B-003-017-005 In a mobile installation, why should the fuse in the DC line to the transceiver be located as near to the battery as possible?
• B-003-017-006 Apart from efficiency, what is one advantage of a switching (switch mode) power supply over a linear power supply?
• B-003-017-007 Why are heavy-gauge wires used for a 100-watt transceiver's DC power connection?
• B-003-017-008 What are the nominal power-line voltages supplied to homes?
• B-003-017-009 Your transceiver's user guide suggests limiting the voltage drop to 0.5 volts and the vehicle battery is 3 metres away. Given the losses listed below at the required current of 22 amperes, which minimum wire gauge must you use?
• B-003-017-010 Why must the positive lead from the vehicle battery to your transceiver be fused?
• B-003-017-011 You have a very loud low-frequency hum appearing on your transmission. In what part of the transmitter would you first look for the trouble?
• B-003-018-001 How could you best keep unauthorized persons from using your station at home?
• B-003-018-002 How could you best keep unauthorized persons from using a mobile station in your car?
• B-003-018-003 What electrical hazard, if any, does the starter battery in a vehicle present?
• B-003-018-004 Why would there be a switch in a high-voltage power supply to turn off the power if its cabinet is opened?
• B-003-018-005 What is the minimum electrical current that can be fatal to the human body?
• B-003-018-006 Which body organ can be fatally affected by a very small amount of electrical current?
• B-003-018-007 What is the lowest voltage that is usually considered hazardous to humans?
• B-003-018-008 What should you do if you discover someone who is being burned by high voltage?
• B-003-018-009 What is the safest method to remove an unconscious person from contact with a high-voltage source?
• B-003-018-010 Before checking a fault in a mains-operated power supply unit, it would be safest to first:
• B-003-018-011 What is the risk involved in troubleshooting a live power supply?
• B-003-019-001 For best protection from electrical shock, what should be grounded in your station?
• B-003-019-002 Established practice demands that all ground electrodes be bonded together with heavy conductors. What protection does this provide in case of a lightning strike?
• B-003-019-003 Why should you never use a fuse with a higher current rating than specified?
• B-003-019-004 Which of these materials is best for a ground rod driven into the earth?
• B-003-019-005 You need to work on a power supply that has been taken offline. What is the first thing you should do once the cabinet is open?
• B-003-019-006 Where should the green wire in a three-wire AC line cord be connected in a power supply?
• B-003-019-007 Your third-floor station has a ground wire running 10 metres down to a ground rod. You get an RF burn when you touch your HF transceiver while transmitting. What is the likely cause?
• B-003-019-008 You are using an HF off-centre-fed (OCF) unbalanced antenna. When you transmit on SSB, distorted audio and noise are heard from an outboard amplified speaker. What device could you install in the transmission line to mitigate this problem?
• B-003-019-009 What is a safe method to discharge power supply filter capacitors?
• B-003-019-010 On mains-operated power supplies, the ground wire of the AC line is connected to the power supply chassis. What protection does this provide if a fault occurs in the power supply?
• B-003-019-011 Why do fuses have a voltage rating?
• B-003-020-001 Why should you ground all antenna and rotator cables when your station is not in use?
• B-003-020-002 You want to install a lightning surge protector on your transmission line, where should it be inserted?
• B-003-020-003 How can your station equipment best be protected from lightning damage?
• B-003-020-004 What equipment should be worn for working on an antenna tower?
• B-003-020-005 Why should you wear approved fall arrest equipment if you are working on an antenna tower?
• B-003-020-006 For safety, how high should you place a horizontal wire antenna?
• B-003-020-007 Why should you wear a hard hat if you are on the ground helping someone work on an antenna tower?
• B-003-020-008 Why should your outside antennas be high enough so that no one can touch them while you are transmitting?
• B-003-020-009 Why should you make sure that no one can touch an open-wire transmission line while you are transmitting with it?
• B-003-020-010 What safety precautions should you take before beginning repairs on an antenna?
• B-003-020-011 What safety precaution is especially important for a ground-mounted antenna?
• B-003-021-001 What should you do for safety when operating at UHF and microwave frequencies?
• B-003-021-002 What should you do for safety if you put up a UHF transmitting antenna?
• B-003-021-003 What should you do for safety, before removing the shielding on a UHF power amplifier?
• B-003-021-004 Why should you make sure the antenna of a hand-held transceiver is not close to your head when transmitting?
• B-003-021-005 How should you position the antenna of a hand-held transceiver while you are transmitting?
• B-003-021-006 How can exposure to a large amount of RF energy affect body tissue?
• B-003-021-007 Which body organ is the most likely to be damaged from the heating effects of RF radiation?
• B-003-021-008 How does the power density of an electromagnetic wave change as it propagates away from an antenna in free space?
• B-003-021-009 If you operate your station with indoor antennas, what precautions should you take when you install them?
• B-003-021-010 Why should directional high-gain antennas be mounted higher than nearby structures?
• B-003-021-011 For best RF safety, where should the ends and centre of a dipole antenna be located?