Radio Wave Propagation

Question 1

Why do VHF signal strengths sometimes vary greatly when the antenna is moved only a few feet?
A. The signal path encounters different concentrations of water vapor
B. VHF ionospheric propagation is very sensitive to path length
C. Multipath propagation cancels or reinforces signals
D. All these choices are correct

Answer 1

C. Multipath propagation cancels or reinforces signals

Multipath is the propagation phenomenon that results in radio signals reaching the receiving antenna by two or more paths. Causes of multipath include atmospheric ducting, ionospheric reflection and refraction, and reflection from water bodies and terrestrial objects such as mountains and buildings. When the same signal is received over more than one path, it can create interference and phase shifting of the signal. Destructive interference causes fading; this may cause a radio signal to become too weak in certain areas to be received adequately. For this reason, this effect is also known as multipath interference or multipath distortion.

Question 2

What is the effect of vegetation on UHF and microwave signals?
A. Knife-edge diffraction
B. Absorption
C. Amplification
D. Polarization rotation

Answer 2

B. Absorption

Question 3

What antenna polarization is normally used for long-distance CW and SSB contacts on the VHF and UHF bands?
A. Right-hand circular
B. Left-hand circular
C. Horizontal
D. Vertical

Answer 3

C. Horizontal

Continuous Wave (CW) is not a modulation technique like AM, FM, or SSB, but rather a mode of operation where the carrier wave is turned on and off according to a predefined pattern, typically to transmit Morse code. Since CW transmits information by simply turning the carrier wave on and off, it is considered the most basic and efficient form of radio communication.

Single Sideband (SSB) is a form of Amplitude Modulation (AM) where one of the sidebands and the carrier wave are removed, leaving only one sideband (either the upper or lower sideband) to carry the information. This makes SSB more efficient in terms of power usage and bandwidth compared to traditional AM.

Question 4

What happens when antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization?
A. The modulation sidebands might become inverted
B. Received signal strength is reduced
C. Signals have an echo effect
D. Nothing significant will happen

Answer 4

B. Received signal strength is reduced

You may have played with polarized glasses sometime and found that if you hold two pair in line with each other and then rotate one 90 degrees that they darken or block light from coming through. Some 3-D movies have you wear polarized glasses where one eye is vertically polarized and the other eye is horizontally polarized so that each eye can receive a different image projected from the two projectors.

With radio we can have vertically or horizontally polarized antennas. The receiver must have the same polarization in order to pick up the maximum amount of the signal transmitted. If they are not matched, they may only detect a small portion and be significantly weaker than it should be. Note the “line of sight” clarification in the question. Once a signal bounces or reflects off of something, it may alter its polarity. If you are having a hard time hearing a transmission, move positions and tilt the antenna around to maximize reception.

Question 5

When using a directional antenna, how might your station be able to communicate with a distant repeater if buildings or obstructions are blocking the direct line of sight path?
A. Change from vertical to horizontal polarization
B. Try to find a path that reflects signals to the repeater
C. Try the long path
D. Increase the antenna SWR

Answer 5

B. Try to find a path that reflects signals to the repeater

The great thing about a directional (or “beam”) antenna is the ability to tightly focus your transmission in a particular direction. If you don’t have a direct path to the receiving station (a repeater, in the case of this particular question), you can point your antenna at something that will “bounce” the signal for you. It’s a little like playing pool (you can’t get the shot you want, so you find another object, at the correct angle, that can ‘bounce’ the shot in the correct direction).

Question 6

What is the meaning of the term “picket fencing”?
A. Alternating transmissions during a net operation
B. Rapid flutter on mobile signals due to multipath propagation
C. A type of ground system used with vertical antennas
D. Local vs long-distance communications

Answer 6

B. Rapid flutter on mobile signals due to multipath propagation

The term “picket fencing” comes from the visual image of watching a light move on the other side of a picket fence (a fence with slats which are separated by a space); you would see the light appear to flicker as it is periodically hidden by a slat and then visible again. Imagine the same effect but with sound / signal – that’s “picket fencing”.

Thus if someone is mobile and their signal flutters in and out it is often called “picket fencing”, though the cause is actually due to the signal taking multiple paths and combining in different ways as they move rather than an actual “picket fence” type impediment between them and the receiving antenna.

Question 7

What weather condition might decrease range at microwave frequencies?
A. High winds
B. Low barometric pressure
C. Precipitation
D. Colder temperatures

Answer 7

C. Precipitation

The main thing to remember is that the higher the frequency, the more RF energy is absorbed (and converted into heat) by water and solids.

Since microwaves are Extremely High Frequency or greater, theweather conditionthat woulddecrease range at microwave frequencieswould beprecipitation. None of the other options have any significant effect.

The easiest way to remember this is your microwave oven. The microwave oven functions as an oven because theoven microwave frequencyused isoptimizedfor being absorbed by water. Because most food contains a large amount of water, this energy absorption readily heats the food in the oven. Microwaves getting absorbed by water and converted into heat is great for heating food, but not for transmitting a radio signal.

If your microwave oven were a longwave or shortwave oven instead, it wouldn’t be much of an oven because your leftovers wouldn’t be getting too terribly warm at the same power.

Question 8

What is a likely cause of irregular fading of signals propagated by the ionosphere?
A. Frequency shift due to Faraday rotation
B. Interference from thunderstorms
C. Intermodulation distortion
D. Random combining of signals arriving via different paths

Answer 8

D. Random combining of signals arriving via different paths

Fading due toRandom combining of signals arriving via different pathsis calledmultipath fading. It is the only option that makes sense in this question.

It is actually possible for reception to betoogood. Sometimes when reception is good a signal will arrive at your receiver after reflecting off of different obstacles, such as mountains, buildings, and so on. Each time this happens, it creates a separate “path”, and each path is a different distance (or length), resulting in signals that are out of phase with each other.

When these signals all arrive, with some taking longer than others, they can combine in such a way that it can cause the total signal to fade such as when the signal along one path is180∘(or close to it) out of phase with another causing the waves to cancel each other out.

When the signals are less out of phase with each other they can also cause a type of distortion calledmultipath distortion.

Question 9

Which of the following results from the fact that signals propagated by the ionosphere are elliptically polarized?
A. Digital modes are unusable
B. Either vertically or horizontally polarized antennas may be used for transmission or reception
C. FM voice is unusable
D. Both the transmitting and receiving antennas must be of the same polarization

Answer 9

B. Either vertically or horizontally polarized antennas may be used for transmission or reception

Skip signalsor skywave propagation can be used to communicate beyond the horizon, at intercontinental distances. It is mostly used in the shortwave frequency bands.

Elliptically polarized signals have a vertical and horizontal component, and thus that component can be received by either ahorizontally or vertically polarized antenna.

If a signal were strictly horizontal, then receiving it on a vertical antenna would result in significant loss. The same when receiving a vertically polarized signal on a horizontal antenna.

Question 10

What effect does multi-path propagation have on data transmissions?
A. Transmission rates must be increased by a factor equal to the number of separate paths observed
B. Transmission rates must be decreased by a factor equal to the number of separate paths observed
C. No significant changes will occur if the signals are transmitted using FM
D. Error rates are likely to increase

Answer 10

D. Error rates are likely to increase

When the same signal propagates over multiple paths the different paths will generally be a slightly different distance and different angles. As a result, the signal arrives at the destination from multiple directions at multiple times. Since radio waves travel at the speed of light, this difference in time will be very minor, but even a slight difference is enough to cause the recombination of those somewhat out of phase with each other signals at the end to create a type of distortion calledmultipath distortion. When the signal is a data signal, this distortion causes information loss leading to higher error rates.

Question 11

Which region of the atmosphere can refract or bend HF and VHF radio waves?
A. The stratosphere
B. The troposphere
C. The ionosphere
D. The mesosphere

Answer 11

C. The ionosphere

Question 12

What is the effect of fog and rain on signals in the 10 meter and 6 meter bands?
A. Absorption
B. There is little effect
C. Deflection
D. Range increase

Answer 12

B. There is little effect

The main thing to remember is that the higher the frequency, the more RF energy is absorbed (and converted into heat) by water and solids.

For10m and 6mwavelengths, the frequency isn’t high enough to be affected byfog and light rainsofog and light rain will have little effect on those bands.

The easiest way to remember this is your microwave oven. The microwave oven is a microwave oven because theoven microwave frequencyused isoptimized for getting absorbed by and thus heating the water in your food.

If your microwave oven were a 10m or 6m wave oven instead, it wouldn’t be much of an oven because your leftovers wouldn’t be getting very warm at the same power usage. 10m and 6m are rather far from “micro” when it comes to wavelength.

Question 13

What property of a radio wave defines its polarization?
A. The orientation of the electric field
B. The orientation of the magnetic field
C. The ratio of the energy in the magnetic field to the energy in the electric field
D. The ratio of the velocity to the wavelength

Answer 13

A. The orientation of the electric field

There’s always an electric and magnetic field to a radio wave, and they’re oriented 90 degrees to each other. You could use either magnetic or electric to define polarization, but it’s conventional to use the electric field (not the magnetic field, or a ratio).

Polarization has nothing to do with the velocity of a radio wave, hence the ratio of velocity to wavelength has nothing to do with polarization.

Question 13

What is the relationship between the electric and magnetic fields of an electromagnetic wave?
A. They travel at different speeds
B. They are in parallel
C. They revolve in opposite directions
D. They are at right angles

Answer 13

D. They are at right angles

Question 13

What are the two components of a radio wave?
A. Impedance and reactance
B. Voltage and current
C. Electric and magnetic fields
D. Ionizing and non-ionizing radiation

Answer 13

C. Electric and magnetic fields

Question 14

What is the velocity of a radio wave traveling through free space?
A. Speed of light
B. Speed of sound
C. Speed inversely proportional to its wavelength
D. Speed that increases as the frequency increases

Answer 14

A. Speed of light

Question 15

What is the relationship between wavelength and frequency?
A. Wavelength gets longer as frequency increases
B. Wavelength gets shorter as frequency increases
C. Wavelength and frequency are unrelated
D. Wavelength and frequency increase as path length increases

Answer 15

B. Wavelength gets shorter as frequency increases

Question 16

What is the formula for converting frequency to approximate wavelength in meters?
A. Wavelength in meters equals frequency in hertz multiplied by 300
B. Wavelength in meters equals frequency in hertz divided by 300
C. Wavelength in meters equals frequency in megahertz divided by 300
D. Wavelength in meters equals 300 divided by frequency in megahertz

Answer 16

D. Wavelength in meters equals 300 divided by frequency in megahertz

Question 17

In addition to frequency, which of the following is used to identify amateur radio bands?
A. The approximate wavelength in meters
B. Traditional letter/number designators
C. Channel numbers
D. All these choices are correct

Answer 17

A. The approximate wavelength in meters

This is a common part of Ham vocabulary. You’ll hear something like: “I was talking on the 2-meter band last night..”, which actually means they were talking somewhere between 144Mhz and 148Mhz (the authorized frequencies with a 2-meter wavelength). Other common terms are 33cm (the 902Mhz band), 70cm (the 440Mhz band), etc. Each frequency range has a corresponding wave-length that hams will refer to.

Question 18

What frequency range is referred to as VHF?
A. 30 kHz to 300 kHz
B. 30 MHz to 300 MHz
C. 300 kHz to 3000 kHz
D. 300 MHz to 3000 MHz

Answer 18

B. 30 MHz to 300 MHz

Question 19

What frequency range is referred to as UHF?
A. 30 to 300 kHz
B. 30 to 300 MHz
C. 300 to 3000 kHz
D. 300 to 3000 MHz

Answer 19

D. 300 to 3000 MHz

Question 20

What frequency range is referred to as HF?
A. 300 to 3000 MHz
B. 30 to 300 MHz
C. 3 to 30 MHz
D. 300 to 3000 kHz

Answer 20

C. 3 to 30 MHz

Question 21

What is the approximate velocity of a radio wave in free space?
A. 150,000 meters per second
B. 300,000,000 meters per second
C. 300,000,000 miles per hour
D. 150,000 miles per hour

Answer 21

B. 300,000,000 meters per second

This is a useful number to know; it is, of course, the speed of light or approximately

3×10^8m/sec = 300,000,000m / sec

One really useful thing about this number is that it comes out to the same range as “Mega” (6 zeros after 300), so it can be used as a quick way to calculate wavelength in MegaHz (MHz).

Question 22

Why are simplex UHF signals rarely heard beyond their radio horizon?
A. They are too weak to go very far
B. FCC regulations prohibit them from going more than 50 miles
C. UHF signals are usually not propagated by the ionosphere
D. UHF signals are absorbed by the ionospheric D region

Answer 22

C. UHF signals are usually not propagated by the ionosphere

Any time you hear stations directly (not using a repeater system) from far away, you can assume some sort of atmospheric condition is helping the signal to travel. Most long-distance radio waves bounce off the ionosphere. However, signals in the UHF spectrum have such a short wavelength that they don’t bounce off the ionosphere at all – they pass right through it into outer space. (This is why higher frequencies are ideal for communicating with satellites). Thus, if you hear a signal in the UHF band, it’s safe to assume the source of that signal is nearby.

Question 23

What is a characteristic of HF communication compared with communications on VHF and higher frequencies?
A. HF antennas are generally smaller
B. HF accommodates wider bandwidth signals
C. Long-distance ionospheric propagation is far more common on HF
D. There is less atmospheric interference (static) on HF

Answer 23

C. Long-distance ionospheric propagation is far more common on HF

Question 24

What is a characteristic of VHF signals received via auroral backscatter?
A. They are often received from 10,000 miles or more
B. They are distorted and signal strength varies considerably
C. They occur only during winter nighttime hours
D. They are generally strongest when your antenna is aimed west

Answer 24

B. They are distorted and signal strength varies considerably

Question 25

Which of the following types of propagation is most commonly associated with occasional strong signals on the 10, 6, and 2 meter bands from beyond the radio horizon?
A. Backscatter
B. Sporadic E
C. D region absorption
D. Gray-line propagation

Answer 25

B. Sporadic E

Memory Aid: Sporadic = Occasional

Every now and then a type of propagation occurs that carries the RF energy within a particular range of frequencies quite a long distance, refracting it in just the right way over and over. This type of propagation is known asSporadic E. It occurs when clouds of intensely ionized gas form in the E region of the earth’s ionosphere typically between 90 and 120 km in altitude. The mechanisms behind the formation of the ionized gas clouds are beyond the scope of this text.

Backscattergenerallyscattersa signalbacktowards its source, which would not result in strong over-the-horizon signals. The operative word inD layer absorptionisabsorptionwhere the RF signal is attenuated, not refracted, in the ionospheric layer closest to the ground.Gray-line propagationis a reference to a 45 - 60 minute period around twilight when D layer absorption is diminished but some refraction of signals on the 10 and 15-meter bands can occur before the solar ionization in the E and F layers is diminished with nightfall.

Question 26

Which of the following effects may allow radio signals to travel beyond obstructions between the transmitting and receiving stations?
A. Knife-edge diffraction
B. Faraday rotation
C. Quantum tunneling
D. Doppler shift

Answer 26

A. Knife-edge diffraction

Question 27

What type of propagation is responsible for allowing over-the-horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis?
A. Tropospheric ducting
B. D region refraction
C. F2 region refraction
D. Faraday rotation

Answer 27

A. Tropospheric ducting

There are several modes that can allow communication that ranges “over-the-horizon” or beyond line-of-sight such as Ducting and Troposheric scatter. The key to differentiate these two in this question is the mentioning of “VHF” frequencies.

Tropospheric scatter is where the signals are bent or reflected back to earth in a somewhat random manner to station a significant distance away on a regular basis. But it works in the UHF and microwave frequencies, and is best around 2 GHz.

Tropospheric ducting happens when a large mass of cold air is overrun by warm air causing a temperature inversion, it is relatively common during summer and autumn months and can work as low as 40 MHz, and most commonly works above 90 MHz which covers most the VHF bands.

Question 28

What band is best suited for communicating via meteor scatter?
A. 33 centimeters
B. 6 meters
C. 2 meters
D. 70 centimeters

Answer 28

B. 6 meters

Meteor scatter communication is done by reflecting radio waves off ionized particles in the ionosphere that were caused by meteors passing through. The 6-meter band is excellent for meteor scatter due to its wavelength, and because it is a quiet band. Wavelengths longer than 6 meters are not effectively reflected by meteor scatter; shorter wavelength bands, such as the 2-meter band, are not as quiet which makes it difficult to hear these weak signals from 500 to 1500 miles away.

Here is a memory aid: The “6” in 6 meters looks like a meteor with a curved tail

Question 29

What causes tropospheric ducting?
A. Discharges of lightning during electrical storms
B. Sunspots and solar flares
C. Updrafts from hurricanes and tornadoes
D. Temperature inversions in the atmosphere

Answer 29

D. Temperature inversions in the atmosphere

To remember this answer, think of heatingductsin a building that carry different-temperatureair long distances from a central unit, just like the temperature inversions that cause tropospheric ducting.

Tropospheric ducting is an atmospheric effect caused by a differential temperature layer that causes reflection or refraction of radio wave. These reflective layers can form a radio wave “duct”, much like the ducts that are used to duct warm or cool air through our homes. These ducts are often caused by thermal inversions and other weather phenomena. Radio wave propagation can extend from 300 to 500 miles, sometimes as far as 1000 miles, through tropospheric ducting.

The troposphere is the lowest level of the atmosphere and is where temperature inversions occur; understanding this relationship will help you choose the correct answer.

Question 30

What is generally the best time for long-distance 10 meter band propagation via the F region?
A. From dawn to shortly after sunset during periods of high sunspot activity
B. From shortly after sunset to dawn during periods of high sunspot activity
C. From dawn to shortly after sunset during periods of low sunspot activity
D. From shortly after sunset to dawn during periods of low sunspot activity

Answer 30

A. From dawn to shortly after sunset during periods of high sunspot activity

Remember that 10 meters follows the sun and thus is best in daylight hours.

The 10 meter band is best during daylight hours due to the nature of this wavelength and how it refracts through or reflects off of the F2 layer of the ionosphere.

During periods of increased sunspot activity, band openings may begin well before sunrise and continue into the night.

In areas near the equator, 10 meters is effective even during periods of low solar activity. This is demonstrated by good propagation between areas in Africa to the Caribbean.

Question 31

Which of the following bands may provide long-distance communications via the ionosphere’s F region during the peak of the sunspot cycle?
A. 6 and 10 meters
B. 23 centimeters
C. 70 centimeters and 1.25 meters
D. All these choices are correct

Answer 31

A. 6 and 10 meters

Question 32

Why is the radio horizon for VHF and UHF signals more distant than the visual horizon?
A. Radio signals move somewhat faster than the speed of light
B. Radio waves are not blocked by dust particles
C. The atmosphere refracts radio waves slightly
D. Radio waves are blocked by dust particles

Answer 32

C. The atmosphere refracts radio waves slightly

Question 33

Which of the following is an appropriate power supply rating for a typical 50 watt output mobile FM transceiver?
A. 24.0 volts at 4 amperes
B. 13.8 volts at 4 amperes
C. 24.0 volts at 12 amperes
D. 13.8 volts at 12 amperes

Answer 33

D. 13.8 volts at 12 amperes

Question 34

Which of the following should be considered when selecting an accessory SWR meter?
A. The frequency and power level at which the measurements will be made
B. The distance that the meter will be located from the antenna
C. The types of modulation being used at the station
D. All these choices are correct

Answer 34

A. The frequency and power level at which the measurements will be made

An SWR meter measures the Standing Wave Ratio in the antenna system; the reason that is useful is that it is an indicator of how closely the impedance of the transceiver matches the impedance of the antenna system – by the Maximum Power Transfer theorem maximum power is transferred when the effective resistance (impedance in this case) of both systems are equal, which means that the maximum benefit of the antenna system can be obtained when the impedance matches on both sides.

Since we’re talking about impedance and power, we only need consider things which affect one or the other. Impedance is basically resistance at a given frequency and power is just whatever the output power are, so the things which the SWR meter might need to care about are going to be those two things.

The distance that the meter will be located from the antenna could affect the reading, but it would affect all SWR meters equally. The type of modulation is going to be immaterial except as it affects the power. Thus those two distracters are just that!

When you buy an SWR meter you’ll find that they have power limits (too much power could blow it out or at least give you a useless reading) and frequency limits; most commonly you’ll find a SWR meter which works at e.g. 0 to 150MHz and handles 100 Watts; thus if you want to operate on 440 (70cm) or you are using a power amplifier and 500 watts you need to make sure that you buy a SWR meter which can handle the correct frequency and power.

Question 35

Why are short, heavy-gauge wires used for a transceiver’s DC power connection?
A. To minimize voltage drop when transmitting
B. To provide a good counterpoise for the antenna
C. To avoid RF interference
D. All these choices are correct

Answer 35

A. To minimize voltage drop when transmitting

Power connectionsshould be:

Heavy gaugebecause heavier gauge wires can conduct more current andhave less resistance for a given length.

Short as possiblebecause even heavy gauge wire has some resistance, andthe longer the wire the more resistance the connection will have.

The more resistance the connection has the more the voltage will drop. So to get the least resistance, and the least voltage drop, you wantshort heavy gauge wire.

A radio or other electronic device may fail to operate properly or even be damaged if a supply line is so long that the voltage on the other end is below a minimum required level.

Question 36

How are the transceiver audio input and output connected in a station configured to operate using FT8?
A. To a computer running a terminal program and connected to a terminal node controller unit
B. To the audio input and output of a computer running WSJT-X software
C. To an FT8 conversion unit, a keyboard, and a computer monitor
D. To a computer connected to the FT8converter.com website

Answer 36

B. To the audio input and output of a computer running WSJT-X software

Memory aid:FT8Is aWeak Signalmode, and runs onWSJT software.

Test Aid:The correct answer is the only one answering the question of how theaudio input and outputare connected, and is the only answer containing the words “audio input and output”.

FT8, or “Franke-Taylor design, 8-FSK modulation”, is a digital signal designed to take advantage of less-than-optimal propagation and allow for contacts where they could not otherwise be made. The software designed for these weak signal modes isWSJT-X, or “Weak Signal Joe Taylor - 10” (Joe Taylor K1JT being the author of the program). This program uses a computer connected to theaudio input and outputof any radio to transmit and receive, then decode, or transmit short messages.

Question 37

Where should an RF power meter be installed?
A. In the feed line, between the transmitter and antenna
B. At the power supply output
C. In parallel with the push-to-talk line and the antenna
D. In the power supply cable, as close as possible to the radio

Answer 37

A. In the feed line, between the transmitter and antenna

As RF power in this context only travels through the feed line from the transmitter, “In the feed linebetween thetransmitterand the antenna” is the only logical answer.

Question 38

What signals are used in a computer-radio interface for digital mode operation?
A. Receive and transmit mode, status, and location
B. Antenna and RF power
C. Receive audio, transmit audio, and transmitter keying
D. NMEA GPS location and DC power

Answer 38

C. Receive audio, transmit audio, and transmitter keying

Just remember that a large number of digital modes (almost all of the ones used on HF, if not all) can be encoded and decoded by the simple sound card in a reasonably modern computer. For example,RTTYusesAFSKand can easily be decoded from audio by modern computers. EvenSlow Scan TVcan be encoded and decoded as audio by desktops, laptops, tablets, and smartphones!

Therefore, the only answer here that makes any sense isreceive audio, transmit audio, and transmitter keying, the last one so computer software can activate and deactivite the transmitter without the need to do so manually.

Often even a computer’s microphone and speaker next to the microphone and speaker of the radio is sufficient to encode and decode digital signals as audio, but obviously this method is more error prone so using audio cables is highly preferable for avoiding errors due to noise in the room.

Question 39

Which of the following connections is made between a computer and a transceiver to use computer software when operating digital modes?
A. Computer “line out” to transceiver push-to-talk
B. Computer “line in” to transceiver push-to-talk
C. Computer “line in” to transceiver speaker connector
D. Computer “line out” to transceiver speaker connector

Answer 39

C. Computer “line in” to transceiver speaker connector

Memory Aid:Line-inListensto aspeaker(Line in, Listen).

With digital modes,your computer needs to listenin order to decode the signal.

Push-to-Talk signals do not connect to Line signals, so both of those answers can be disregarded.

“Line Out” would connect to the transceiver’s Mic In connection and not the speaker.

Therefore, think of the audio path for the correct answer: Audio Out of the receiver (normally via thespeaker) needs to gointothe computer to be decoded.

Question 40

Which of the following conductors is preferred for bonding at RF?
A. Copper braid removed from coaxial cable
B. Steel wire
C. Twisted-pair cable
D. Flat copper strap

Answer 40

D. Flat copper strap

Question 41

How can you determine the length of time that equipment can be powered from a battery?
A. Divide the watt-hour rating of the battery by the peak power consumption of the equipment
B. Divide the battery ampere-hour rating by the average current draw of the equipment
C. Multiply the watts per hour consumed by the equipment by the battery power rating
D. Multiply the square of the current rating of the battery by the input resistance of the equipment

Answer 41

B. Divide the battery ampere-hour rating by the average current draw of the equipment

This formula gives you a good idea of roughly how long your battery would be able to perform. As an example, if you have a 24AH battery and a radio that draws 1A on receive and 12A on transmit:

24AH / 1 A = 24 hours of receive-only.

and

24AH / 12A = 2 hours of transmit-only

You can see by this that you have somewhere between 2 and 24 hours of use for the given setup, depending on how much you transmit, and at what power output (if adjustable).

NOTE: This formula does not take into consideration how much charge you plan to leave on your battery before recharging, heat/cold exposure, and other environmental factors that may affect operational capacity of the battery.

Question 42

What function is performed with a transceiver and a digital mode hot spot?
A. Communication using digital voice or data systems via the internet
B. FT8 digital communications via AFSK
C. RTTY encoding and decoding without a computer
D. High-speed digital communications for meteor scatter

Answer 42

A. Communication using digital voice or data systems via the internet

Digital Mode hot spots are semi-automatic transceivers which provide a gateway between radio frequencies and other stations across the internet.

As an example, you could program your Digital Mobile Radio (DMR) to use a DMR hotspot and then you use DMR on your radio however you would normally use it and as long as you are in range of that hotspot you can communicate with other DMR stations across the internet. This becomes even more interesting when you realize that some of those stations may be using not hotspots but full DMR repeaters, which enables some of the following interesting scenarios:

You go out of town and take your hotspot; you can then call across the hotspot to talk to people who are using a DMR repeater near your house.

You are located in an area with few active repeaters, so you use your DMR hotspot to let you communicate with people on an active repeater in another area

You set up a talk group with the other people in the online ham radio group you are a member of; anyone with a hotspot can get on and talk to anyone else with a hotspot or local DMR repeater who has their radio on and connected.

While I’ve used DMR for these examples similar things can be done with most digital modes including D-Star and System Fusion and some hotspots can even work on any of those modes.

Question 43

Where should the negative power return of a mobile transceiver be connected in a vehicle?
A. At the 12 volt battery chassis ground
B. At the antenna mount
C. To any metal part of the vehicle
D. Through the transceiver’s mounting bracket

Answer 43

A. At the 12 volt battery chassis ground

A mobile transceiver can draw many Amperes of current when transmitting. That current needs to come directly from the battery. Using another electrical path could reduce the current available and hinder the tranceiver’s performance.

Question 44

What is an electronic keyer?
A. A device for switching antennas from transmit to receive
B. A device for voice activated switching from receive to transmit
C. A device that assists in manual sending of Morse code
D. An interlock to prevent unauthorized use of a radio

Answer 44

C. A device that assists in manual sending of Morse code

Question 45

What is the effect of excessive microphone gain on SSB transmissions?
A. Frequency instability
B. Distorted transmitted audio
C. Increased SWR
D. All these choices are correct

Answer 45

B. Distorted transmitted audio

Question 46

Which of the following can be used to enter a transceiver’s operating frequency?
A. The keypad or VFO knob
B. The CTCSS or DTMF encoder
C. The Automatic Frequency Control
D. All these choices are correct

Answer 46

A. The keypad or VFO knob

A VFO Knob, sometimes called a Tuning Knob, Tuning Dial (as on vintage analog receivers), or on some HTs, a channel selector or MULTI knob, is the knob that adjusts the Transmit/Receive operating frequency of a transceiver, receiver or transmitter, on traditional base station and mobile rigs, along with scanners and vintage domestic broadcast receivers, the VFO knob is typically the biggest knob on the radio.

Question 47

How is squelch adjusted so that a weak FM signal can be heard?
A. Set the squelch threshold so that receiver output audio is on all the time
B. Turn up the audio level until it overcomes the squelch threshold
C. Turn on the anti-squelch function
D. Enable squelch enhancement

Answer 47

A. Set the squelch threshold so that receiver output audio is on all the time

The squelch option on a radio is meant to suppress or mute sound when transmissions are not being received. This works by muting the receiver until a received signal strength exceeds the squelch setting. If the squelch is all the way down (i.e. receiver is never muted), then received transmissions of any strength will be heard on your transceiver, including weak FM signals with low output power.

Question 48

What is a way to enable quick access to a favorite frequency or channel on your transceiver?
A. Enable the frequency offset
B. Store it in a memory channel
C. Enable the VOX
D. Use the scan mode to select the desired frequency

Answer 48

B. Store it in a memory channel

Question 49

What does the scanning function of an FM transceiver do?
A. Checks incoming signal deviation
B. Prevents interference to nearby repeaters
C. Tunes through a range of frequencies to check for activity
D. Checks for messages left on a digital bulletin board

Answer 49

C. Tunes through a range of frequencies to check for activity

Question 50

Which of the following controls could be used if the voice pitch of a single-sideband signal returning to your CQ call seems too high or low?
A. The AGC or limiter
B. The bandwidth selection
C. The tone squelch
D. The RIT or Clarifier

Answer 50

D. The RIT or Clarifier

RIT stands for Receiver Incremental Tuning. It is a fine tuning control to adjust the receiver frequency without adjusting the transmitter frequency.

While SSB is a very efficient transmission mode, everyone ends up sounding somewhat like Donald Duck. This is due to the fact that the transmit carrier frequency is missing. RIT Stands for Receiver Incremental Tuning which in effect, recreates the signal’s missing carrier transmit frequency. When the RIT adjustment is misadjusted, the result can be a voice which is too high or too low sounding. Adjust the RIT until the voice sounds correct. Keep in mind some people have naturally higher voices than others. The direction you adjust the RIT will be in opposite directions for upper sideband (USB) vs. lower sideband (LSB), SSB signals.

Question 51

What does a DMR “code plug” contain?
A. Your call sign in CW for automatic identification
B. Access information for repeaters and talkgroups
C. The codec for digitizing audio
D. The DMR software version

Answer 51

B. Access information for repeaters and talkgroups

Digital mobile radio (DMR) is a digital radio standard for voice and data transmission in non-public radio networks.

Question 52

What is the advantage of having multiple receive bandwidth choices on a multimode transceiver?
A. Permits monitoring several modes at once by selecting a separate filter for each mode
B. Permits noise or interference reduction by selecting a bandwidth matching the mode
C. Increases the number of frequencies that can be stored in memory
D. Increases the amount of offset between receive and transmit frequencies

Answer 52

B. Permits noise or interference reduction by selecting a bandwidth matching the mode

Different modes use different amounts of bandwidth; if you are using a narrow receive bandwidth and the mode is wide FM, you will only “hear” a portion of the signal. On the other hand if you’re using a wide FM receive bandwidth and the mode is narrow FM, you may not be able to make out the signal at all and there could be interference from other stations on nearby frequencies. The best signal will be experienced when the receiver is expecting the same amount of bandwidth that the transmitter is transmitting.

Question 53

How is a specific group of stations selected on a digital voice transceiver?
A. By retrieving the frequencies from transceiver memory
B. By enabling the group’s CTCSS tone
C. By entering the group’s identification code
D. By activating automatic identification

Answer 53

C. By entering the group’s identification code

Question 54

Which of the following receiver filter bandwidths provides the best signal-to-noise ratio for SSB reception?
A. 500 Hz
B. 1000 Hz
C. 2400 Hz
D. 5000 Hz

Answer 54

C. 2400 Hz

Hearing Frequency Range Starting with the main frequency range, it is the frequency range of human hearing, which is responsible for the perception of speech. It covers the frequencies from 300 to 3000 Hz. The range of frequencies in which the intelligibility and the recognition of the tuning characteristics are concerned is between the above mentioned frequency. This frequency range is used for voice communication in telephony and is the range the human ear is the most sensitive. Because of this, a 2400Hz filter will generally leave enough of the voice characteristics to be understandable but filter out much of the noise.

Question 55

Which of the following must be programmed into a D-STAR digital transceiver before transmitting?
A. Your call sign
B. Your output power
C. The codec type being used
D. All these choices are correct

Answer 55

A. Your call sign

D-STAR (Digital Smart Technologies for Amateur Radio) is a digital voice and data protocol specification for amateur radio.

Question 56

What is the result of tuning an FM receiver above or below a signal’s frequency?
A. Change in audio pitch
B. Sideband inversion
C. Generation of a heterodyne tone
D. Distortion of the signal’s audio

Answer 56

D. Distortion of the signal’s audio