These highlights are from the Kindle version of Craig “Buck” K4IA’s Amateur Radio Technician Class book, part of my larger collection of book highlights.
The test is 35 questions from a possible pool of 424. The questions and the answers on your test are word-for-word out of the published question pool.
The pool is large but only about one in a dozen questions will show up on your exam, one from each of the test subjects.
There are three license classes: Technician, General, and Amateur Extra each conferring more privileges.
Do you know what they call the medical student who graduates last in his class? “Doctor” – the same as the guy who graduated first in the class. My point is: all you need is to pass, and no one will know the difference. To pass, answer 26 out of 35 correctly.
Radio waves are electromagnetic. The ionosphere is the part of the atmosphere that enables propagation around the world.
An electrical wiring diagram that uses standard component symbols is called a schematic. Hint: The short answer is, “A wiring diagram is a schematic.”
We use rosin-core solder because Dad’s acid-core plumbing solder would corrode the joint. I also learned that cold solder joints are not good. Cold solder joints look grainy and dull and make a bad connection. You need to reheat the joint and try again.
Non-rechargeable batteries are carbon-zinc batteries. Types of rechargeable batteries are: Nickel-metal hydride Lithium-ion Lead-acid gel-cell All the choices are correct. Hint: Lots of rechargeable battery types so all are correct. Cheat: You don’t have to recite the correct answers just know they are all correct.
If you charge or discharge lead-acid batteries too quickly, they can overheat, give off flammable gas, or explode
Voltage is electromotive force. The basic unit is the volt. We could measure it with a voltmeter hooked up in parallel with (across) the circuit – from one end of the battery to the other.
You do have to be careful when measuring high voltages. Ensure that the meter and leads are rated at the voltages to be measured.
Current flowing through a body may cause a health hazard by: Heating tissue Disrupting electrical functions Causing involuntary muscle contractions All of the choices are correct.
The flow of electrons is called current. Electrical current is measured in amperes (amps) with an ammeter. An ammeter is connected in series (in line) with the circuit. You measure flow through the circuit.
Copper is a good conductor, but there is some resistance to the flow of current even in copper wire. A good insulator is glass. It has a very high resistance and won’t pass current.
Resistance is measured in ohms. The instrument to measure resistance is an ohmmeter.
The component that is used to protect other circuit components from current overloads is a fuse. Don’t put a 20 amp fuse in place of a 5 amp fuse or excessive current could cause a fire.
K4IA, VR6TC, SY2A – what does it all mean? The country’s communications agency issues call signs. In the United States, the FCC, Federal Communications Commission regulates and enforces the rules. Worldwide, regulation is through the International Telecommunications Union (ITU) which is a United Nations agency for information and communication technology issues . Each country is assigned prefixes so you can tell a person’s location from the prefix.
A valid US Technician class amateur radio call sign would be K1XXX
You use the call sign to identify yourself, in English, at least every 10 minutes and at the end of your conversation.
Fortunately, the FCC has a vanity license program. Once you get your first FCC assigned call sign, any licensed amateur can apply for a different call sign.
Individuals get a call sign, but it is also possible to form a club, and the club receive a call sign. The club must have at least four members. Cheat: remember four to form.
The purpose of the Amateur Radio Service is advancing skills in the technical and communication phases of the radio art. Hint: Radio art? That odd phrase should stick with you as the right answer.
Worldwide, regulation is through the International Telecommunications Union (ITU) which is a United Nations agency for information and communication technology issues. Hint: Don’t memorize this – recognize ITU=worldwide= United Nations.
There are three classes of amateur radio licenses. The entry level is called the Technician Class. The Technician Class license authorizes you to transmit mainly on the: VHF (Very High Frequency 30 – 300 MHz) and UHF (Ultra High Frequency 300 – 3000MHz) bands which are suitable for local communication.
(HF, High Frequency: 3 – 30 MHz) bands are sometimes called “short-wave” and are suitable for worldwide communication.” Techs have some limited privileges on HF. We’ll deal with frequencies and bands later but let’s keep it simple for now. The dividing lines are: 3-30, HF (High Frequency) 30-300 VHF (Very High Frequency) 300-3000 UHF (Ultra High Frequency)
When using tactical identifiers, your station must transmit the FCC-assigned call sign every 10 minutes during and at the end of a conversation. Hint: “Every ten minutes.” This rule never changes.
When making on-the-air test transmissions, identify the transmitting station. You should always identify.
You’re required to identify with your call sign in English every 10 minutes during and at the end of your contact. The rest of the time you can speak any language you want.
You’re not allowed to use secret codes. You can transmit encoded messages when transmitting control commands to space stations or radio control craft. Those beeps and whistles are understood by the craft. You can transmit without on-the-air identification when transmitting signals to control model craft.
The FCC defines a “space station” as an amateur station more than 50 km above the earth’s surface. Hint: Remember “more than 50km.”
Your US amateur radio license entitles you to operate from any vessel or craft located in international waters and documented or registered in the United States. Remember, “International waters.”
An amateur station is authorized to transmit music only when incidental to manned spacecraft communications.
Hams aren’t supposed to engage in “broadcasting.” Broadcasting means transmissions intended for reception by the general public as opposed to transmissions sent to a particular station. Broadcasting, program production or news gathering is authorized where such communications relate to the immediate safety of human life or the protection of property.
An amateur station is never permitted to transmit without a control operator. Only a licensed ham can be a control operator. The class of operator license held by the control operator determines the transmitting privileges of an amateur station.
Automatic control is when there are no adjustments made to equipment, no spinning of dials or twisting of knobs to change frequency or adjust volume. Repeater operation is an example of automatic control . The equipment operates automatically, and you don’t have to adjust anything or be in front of it. A station that simultaneously retransmits the signal of another on a different channel or frequency is a repeater.
The abbreviation, RF, refers to radio frequency.
A radio wave is made up of electromagnetic energy. It is called an electromagnetic wave. A radio wave has two components: an electric and a magnetic field.
A radio wave travels through free space at the speed of light. The approximate velocity is 300,000,000 meters per second.
Radio waves act like alternating current. That is, the direction of flow reverses in cycles, unlike a battery. Direct current is the name for current that flows only in one direction. Alternating current is the name for current that reverses direction on a regular basis.
Frequency is the term describing the number of times per second that an alternating current makes a complete cycle. We measure frequency in cycles per second. The term “hertz” is a shortcut for “cycles per second.” The unit of frequency is hertz.
The proper abbreviation for megahertz is MHz. Remember Capital M and capital H; Mr. Hertz.
The electromagnetic spectrum is commonly broken down into three groups: 3 to 30 MHz HF (High Frequency) 30 to 300 MHz VHF (Very High Frequency) 300 to 3000 MHz UHF (Ultra High Frequency)
If we know the wave is traveling at 300 million meters per second, and the frequency is 144 million cycles per second, we can calculate how far the wave will travel in one cycle. Wavelength is the name for the distance a radio wave travels during one complete cycle.
The higher the frequency, the more often the wave reverses direction and the less distance it can travel in a cycle. Therefore, the wavelength gets shorter as the frequency increases.
The formula for converting frequency to wavelength in meters is “wavelength in meters equals 300 divided by frequency in megahertz.” For example, if the frequency is 150 MHz, the wavelength is 300 divided by 150 or 2 meters. The same formula works in reverse: Divide 300 by the wavelength in meters to come up with frequency. 300/2 meters = 150 Mhz. Cheat: The only correct answer has “300 divided by.”
Let’s jump now to the concept of a “band.” A band is a group of frequencies. You’re no doubt familiar with the AM radio band that stretches from 550 kHz to 1600 kHz. The 2 meter amateur band goes from 144 – 148 MHz. The property of radio waves often used to identify the different frequency bands is the approximate wavelength. For example, 146.52MHz is in the 2 meter band. (300/146.52 = about 2)
An exception to the “closest answer” is for 6 meters. The frequency 52.525 MHz is within the 6 meter amateur band. 300/6 = 50 and that is the bottom of the 6 meter band. Cheat: 52.525 MHz is a repeating number and stands out from the other answers
After a while, you’ll catch on, and when someone refers to the 2 meter band, you’ll know they mean 144 to 148 MHz without thinking.
Your amateur radio license authorizes you to transmit on certain bands. Not all frequencies are available to amateurs, and not all amateurs can transmit on all amateur frequencies. The higher the class license, the more operating privileges. Most hams have a chart in the shack because it is easier than trying to memorize the restrictions.
Modulation describes combining speech with an RF carrier. The RF carrier is the base frequency of the transmission. AM is amplitude modulation, and FM is frequency modulation. Amateur radio operators use many different modes.
The following are digital communications modes: IEEE 802.11 Packet JT65 All these choices are correct Hint: Recognize, don’t memorize. If you recognize two out of the three, the answer must be all of the above. There is more on digital modes in the chapter about computers.
NTSC is fast-scan color TV. Cheat: C for color.
The typical bandwidth of analog fast-scan TV transmissions is about 6 MHz . That is the equivalent of 40,000 CW signals. Cheat: Remember TV6.
If you are told you are over-deviating, talk further away from the microphone. Your signal is too wide and might interfere with others.
FM is most commonly used for VHF and UHF voice repeaters.
The approximate bandwidth of a VHF repeater FM phone signal is between 10 and 15 kHz.
Single sideband (SSB) is a form of amplitude modulation (AM).
The voice mode used for long distance weak signal contacts on VHF and UHF is SSB. Single sideband carries better than the other voice modes.
Upper sideband (USB) is normally used for 10 meter HF, VHF, and UHF single sideband communications . Cheat : The answer to remember for the test is “upper.” There is no test question with a correct answer of “lower.”
The approximate bandwidth of a single sideband (SSB) voice signal is 3 kHz. (3000 Hertz) SSB is quite a bit narrower than FM (10-15kHz) or AM (6kHz). Cheat: Remember SSB has three letters.
The advantage of single sideband over FM for voice transmissions is SSB signals have a narrower bandwidth. More signals can fit in a given part of the radio spectrum. Narrower signals also mean you can use narrow filters to reduce noise and interference.
Our early radios had very poor selectivity. That meant you heard many signals, and it was it difficult to pick out the one you wanted to hear. The ability to discriminate between multiple signals is called selectivity. To get more selectivity, we use filters to reduce the bandwidth of the receiver.
You would use a filter 2400 Hz wide for minimizing noise and interference on SSB.
SSB voice modulation is most often used for long distance or weak signal contacts on the VHF and UHF bands.
If the voice pitch seems too high or too low, you would use the receiver RIT (Receiver Incremental Tuning) or Clarifier control to fine tune. The voice pitch is off because you are slightly off frequency. The RIT or Clarifier fine-tunes the receive frequency without changing your transmit frequency.
CW, which stands for continuous wave or carrier wave, is the most basic of digital modes. The carrier is turned on and off making the dots and dashes we read as Morse code. There were several versions of Morse code, but International Morse code is used when sending CW in the amateur bands.
You are not allowed to use codes or ciphers that hide the meaning of a message except when transmitting control commands to space stations or radio remote control craft.
In comparison to SSB and FM, CW emission has the narrowest bandwidth. The approximate maximum bandwidth required to transmit a CW signal is 150 Hz. That means almost 20 CW signals can fit in the same space as one SSB signal.
The typical filter used for CW is 500 Hz wide.
An electronic keyer assists in the sending of Morse code. Instead of pumping a key up-and-down, you push a lever one way to generate a string of dots and another way for dashes. Much faster.
The advantage of having multiple bandwidth choices is it permits noise or interference reduction by selecting a bandwidth matching the mode.
As a Technician class operator, you have HF phone privileges on 10 meters only. A Technician class operator has HF, RTTY, and data privileges on 10 meters only. Cheat: The answer to both questions about HF is 10 meters.
In the HF bands, a Technician is limited to 200 watts output power. Above 30 MHz, a Technician can use up to 1500 watts.
The VHF frequencies limited to CW only are 50 MHz to 50.1 MHz and 144.00 MHZ to 144.1MHZ. Cheat: This is the only answer with VHF frequencies.
Between 219 and 220 MHz, is limited to fixed digital messaging forwarding systems only. Hint: Just remember “fixed digital.”
When the Amateur Radio Service is secondary, you may find non-amateur stations and must avoid interfering. Hint: We are secondary, and you must defer to the primary user and not interfere.
You should not set your transmit frequency to be exactly at the edge of an amateur band: To allow for a calibration error in the transmitter display frequency.
The national calling frequency on the 2 meter band is 146.520 MHz. That is the watering hole where everyone goes to look for a contact. Cheat: When the test asks for a “national calling frequency” you only need to recognize one answer: 146.520 MHz.
The term, picket fencing, is commonly used to describe the rapid fluttering sound sometimes heard from mobile stations that are moving when transmitting. Picket fencing is a rapid in-and-out flutter usually caused by multi-path distortion.
The part of the atmosphere called the ionosphere enables the propagation of radio signals around the world. The ionosphere is clouds of ions energized by the sun. Signals bounce (refract) off the ionosphere and are reflected back to Earth; a phenomenon called “skip.” In some cases, the signals will bounce off the ionosphere back to Earth back to the ionosphere and back to the Earth again for what is called “multi-hop” propagation.
The peak of the sunspot cycle makes long-distance communication possible on six or ten meters. The peak of the sunspot cycle brings more solar energy to the ionosphere and better propagation. Hint: The other answers are all UHF bands which do not refract off the ionosphere.
Direct UHF signals (not on a repeater) are rarely heard from stations outside your local coverage area because UHF signals are usually not reflected by the ionosphere. VHF and UHF frequencies pass through the ionosphere and out into space. That is why VHF and UHF frequencies are used to communicate with satellites.
The range of VHF and UHF signals might be greater in the winter because there is less absorption by vegetation. Trees can absorb VHF and UHF signals.
Fog and light rain have little effect on 10 and 6 meters. HF is not much affected by weather. At microwave frequencies, precipitation can decrease range. “Microwave” is another way of saying “UHF.”
Signals can also bounce off buildings or bend around a sharp corner. Knife-edge diffraction might cause signals to be heard despite obstructions between the transmitting and receiving stations. The term “knife-edge diffraction refers to signals that are partially refracted around sharp edges of solid objects. The term “refracted” is another way of saying “bent.”
Radio waves can refract off more than just the ionosphere and buildings. One example is called “tropospheric ducting.” Tropospheric ducting is caused by temperature inversions in the atmosphere. The radio waves are trapped between layers of different temperature air and bounce along until they squirt out some ways away.
The phenomenon responsible for allowing over the horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis is tropospheric scatter.
Another propagation example is called “auroral reflection.” Signals traveling near the North or South Pole may reflect off the Aurora Borealis, or northern lights. Signals exhibiting rapid fluctuations of strength and often sounding distorted is a characteristic of signals received via auroral reflection. On HF, signals traveling over the North Pole from Asiatic Russia will often sound spooky, watery or fluttery. This sound is classic aurora.
When meteors pass through the atmosphere, they leave behind a short-lived trail of ionized gas. Radio waves will bounce off the ionized gas. The 6 meter band can be very active during times of known meteor showers. The band best suited to communicating via meteor scatter is 6 meters. Cheat: “Meteor” has 6 letters, 6 meter = meteor.
Occasional strong over-the-horizon signals on the 10, 6, and 2 meter bands are sporadic E. Cheat: If you see “sporadic” in an answer, it is right.
A fuse protects circuits from current overloads. A thin metal strip in the fuse overheats and melts, breaking the connection. The purpose of a fuse is to interrupt power in case of an overload.
Don’t put a 20-ampere fuse in place of a 5-ampere fuse or excessive current could cause a fire.
The green wire on a plug goes to safety ground . Hint: Green for ground. That is the lone pin on an electric plug.
To determine the minimum safe distance from a power line, make sure if the antenna falls, it can come no closer than a minimum of 10 feet . If your pole is 30 feet long, be sure you are at least 40 feet from the power line. Measure and put something on the ground, so you don’t wander into danger.
VHF and UHF radio are non-ionizing radiation . RF radiation differs from ionizing radiation (radioactivity) because RF does not have sufficient energy to cause genetic damage. No evidence yet that RF causes cancer.
The factors affecting RF exposure are: Frequency and power level Distance from the antenna Radiation pattern of the antenna . All these choices are correct . Exposure limits vary with frequency because the human body absorbs more RF at some frequencies than others.
If you run more than 50 watts at the antenna on VHF frequencies, you are supposed to do an RF exposure evaluation. Cheat: The answer, both here and above, is “50.” 50 watts and 50 MHZ. To stay in compliance, you should re-evaluate whenever you change equipment.
An acceptable way to check exposure is using: FCC Bulletin Computer modeling Measurement of field strength using calibrated equipment All these choices are correct. Hint: Lots of ways to check, so all the choices are correct.
A person touching your antenna might get a painful RF burn.
If you are transmitting and receiving on the same frequency, it is simplex communication . Hint: One frequency is simple(x).
You can also enter your frequency by typing it on a keypad or use the VFO knob. VFO stands for “variable frequency oscillator,” and you would be turning the knob to change frequency.
An oscillator is a circuit that generates a signal at a specific frequency.
Your HT, hand-held or handy-talkie is a transceiver. The short rubberized antenna that came on top of your HT is called a “rubber duck.” A disadvantage of the “rubber duck” antenna supplied with most handheld radio transceivers is it does not transmit or receive as effectively as a full-sized antenna. It is handy but too short.
A good reason not to use a handheld transceiver inside your car is that signals may not propagate as well due to the shielding effect of the vehicle. The metal car body acts like a shielded cage trapping the signals inside. Mount an antenna outside the vehicle.
The squelch control mutes the receiver output noise when no signal is present. Hint: Tie the words “squelch” and “mute” together.
A sub-audible tone transmitted along with normal voice audio to open the squelch of a receiver is called CTCSS. Coninuous Tone-Coded Squelch System. The tone activates the receiver eliminating unwanted conversations.
There are a dozen or so “Q” signals in common use. You only need to know these two for the Technician test. Q signals are both shorthand and a universal language. If I tell a Russian “QRM,”, I am telling him “I am receiving interference” QRM. He doesn’t speak English, and I don’t speak Russian, but the point is understood. Another example is I am changing frequency: QSY.
A Grid Locater is a letter-number assigned to a geographic location. The world is divided into “Maidenhead Grid Squares.” Someone might not know the location of Fredericksburg, VA but they can find Grid Square FM18.
If you are not using a repeater, you would call CQ. CQ means calling any station.
To call another station on the repeater, if you know his call sign, say the other station’s call sign, then identify with your call sign . “W3ABC this is K4IA.”
Simplex communication is the term used to describe an amateur station transmitting and receiving on the same frequency. Simplex channels are designated in the VHF/UHF band plans so stations can communicate directly without using a repeater.
Simplex communication is the term used to describe an amateur station transmitting and receiving on the same frequency. A repeater operates in “duplex” mode. Since a repeater is receiving and transmitting at the same time, it makes sense that it cannot do both on the same frequency. It would interfere with itself. The repeater listens and talks on two different frequencies simultaneously to prevent self-interference.
“Repeater offset” is the difference between a repeater’s transmit and receive frequencies. A common repeater offset in the 2 meter band is plus or minus 600 kHz. For example, my local repeater receives on 147.615 MHz and retransmits on 147.015 MHz. To access the repeater, you would tune your receiver to 147.015 so you can hear the repeater, and you would set the offset on your radio to transmit +600 kHz so the repeater can hear you.
A common repeater frequency offset in the 70 cm band is plus or minus 5 MHz. The 70 cm band is much wider than the 2 meter band, and there is plenty of room to spread out, so the repeater offset is greater.
Continuous Tone Coded Squelch System (CTCSS) is the term used to describe the use of the sub-audible tone transmitted with normal voice audio to open the squelch of a receiver. Remember, CTCSS opens the squelch.
If you can hear a repeater’s output but can’t access it, a reason might be: Improper transceiver offset The repeater may require a CTCSS tone’ The repeater may require a DCS tone All of these choices are correct.
APPS for iPhone and Android use the GPS in your phone to locate nearby repeaters and provide access information. Look for an APP called “Repeater Book.”
DMR (Digital Mobile Radio or Digital Migration Radio) describes a system for time-multiplexing two digital voice signals on single repeater channel. Hint: Ditch the over-complicated answer and know two people can talk on the same channel with DMR.
It helps if you start off on a frequency where other people commonly listen. These are called “calling frequencies.” The national calling frequency for FM simplex operations in the 2 meter band is 146.520 MHz. Cheat: The test only asks one calling frequency, so memorize 146.520.
If you are looking to establish a contact on HF, you can call CQ. The meaning of the procedural signal “CQ” is calling any station. You would say, “CQ CQ CQ this is K4IA calling CQ and listening.” We don’t use CQ on a repeater.
You identify every ten minutes and at the end of your communication (conversation).
To get the attention of a net control station in an emergency, begin your transmission by saying ”Priority” or “Emergency” followed by your call sign. Use the same protocol on a repeater if you come across an accident and want to summon help.
There are two groups that organize for emergency communications: RACES and ARES. RACES is: A radio service for emergency management and civil defense
ARES is also an organization for emergency communications. ARES is licensed amateurs who have voluntarily register their qualifications and equipment for communications duty. Cheat: ARES has an R in it and you register.
What RACES and ARES have in common is that both may provide communications during emergencies.
Messages have a preamble. The preamble contains to the information needed to track the message as it passes through the system. Think of it as the “to” and “from.”
Another part of a message is the “Check”. Check is a count of the number of words in the text portion of the message . If the “check” is 27 and you only count 25 words, you missed something.
A satellite beacon is a transmission from a satellite that contains status information. Telemetry is the one-way transmission of measurements. Telemetry information typically transmitted by satellite beacons is information about the health and status of a satellite.
The mode of transmission used for satellite beacons is RTTY (teletype) CW (Morse code) Packet (short bursts of digital data) All of these choices are correct.
Satellites move quickly. Satellite tracking programs provide maps showing: The position of the satellite Time azimuth and elevation The Doppler shift. All choices are correct.
The inputs to a satellite tracking program are the Keplerian elements. These are equations and solutions that track the satellite as it orbits the rotating Earth.
UHF signals are usually not reflected by the ionosphere. The signal goes right through. That is why satellite communication uses high frequencies.
A satellite operating in U/V mode is using an uplink in the 70 centimeter band and a downlink in the 2 meter band . Think of it as a repeater with an offset that is using two different bands. Hint: 70 centimeters is UHF and VHF is 2 meters.
A computer might be used as part of an amateur radio station For logging contacts For sending and receiving CW For generating and decoding digital signals All of these choices are correct Hint: Lots of uses.
Digital communications modes include: Packet, IEEE 802.11 JT65 All of these choices are correct.
Packet is a digital system that sends bursts of data. Included in a packet transmission are a: Header with the call sign of the station to which the information is sent Check sum which permits error detection Automatic repeat request in case of error All the answers are correct
An ARQ transmission system detects errors and sends a request to retransmit. (Automatic Repeat Query). If the numbers don’t add up, the receiving station automatically asks for a repeat.
APRS is another use for packet. APRS means Automatic Packet Reporting System.
An application of APRS is to provide real-time tactical digital communications in conjunction with a map showing the locations of stations. Data to the transmitter for automatic position reports is supplied by a GPS Global Positioning System receiver.
Your computer sound card can also generate PSK, which stands for Phase Shift Keying. Hint: The key word is “phase.” PSK is a popular digital mode on HF.
WSJT is a suite of digital protocols that support very weak signal work. The following activities are supported by digital mode software in the WSJT suite: Moonbounce or Earth-Moon-Earth Weak signal propagation beacons Meteor scatter All of these choices are correct Hint: All are weak signal activities.
One program in the WSJT suite is FT8. FT8 is a digital mode capable of operating in low signal-to-noise conditions that transmits at 15-second intervals. Hint: Just recognize FT8 operates at “low signal levels” or “every 15 seconds.”
The presence of a signal is determined by the receiver’s sensitivity. A receiver’s selectivity is the ability to discriminate between signals.
It all starts with an oscillator – the circuit that generates a signal at a specific frequency. Then, you convert a signal from one frequency to another with a mixer. You convert the RF input and output to another band using a transverter . A transverter is a type of mixer. It is a “transverter” because it also transmits. The keyword is “output.” That tells us you are converting a transmitter, thus a transverter. Cheat: If you see transverter in an answer, it is always right.
Power line noise or ignition noise might go away if you turn on the noise blanker . Hint: Blank the noise with a noise blanker.
Another receiver circuit is called AGC – Automatic Gain Control keeps the received audio relatively constant . AGC knocks down the gain if you come across a loud station so you don’t blow out your ears.
If your receiver needs a little help with weak signals, you would put an RF preamplifier between the antenna and receiver. It is an amplifier that is “pre” or before the radio and boosts the signal.
A mobile transceiver typically requires about 12 volts. You hook to the car battery. At home, you need a power supply to convert 120-volt house service. The component commonly used to change 120V AC house current to a lower voltage is a transformer. Hint: A transformer transforms. The circuit that controls the amount of voltage from a power supply is a regulator. Hint: It regulates.
Your radio runs off direct current, but the house power is alternating current. The device that changes an alternating current to direct current is a rectifier.
To determine the minimum current capacity needed for a transceiver power supply, you need to consider: Efficiency of the transmitter at full output Receiver and control circuit power Power supply regulation and heat dissipation All of the choices are correct.
On FM, the amount of deviation is determined by the amplitude (loudness). If you are told you are over-deviating, move away from the microphone. You are too loud and your signal is too wide.
A high-pitched whine in a mobile transceiver that varies with speed is usually the car’s alternator.
Sometimes, RF can get into the audio and be rebroadcast. That is RF feedback. A symptom of RF feedback is reports of garbled, distorted or unintelligible transmissions . Poor grounding or being close to your antenna can cause feedback.
RF can get into your microphone cable, power cable or cables connected to the computer. To cure distorted audio caused by RF current on the shield of a microphone cable use a ferrite choke. Ferrite is a mixture of ceramic and metal that increases the effectiveness of a coil to resist the passage of RF. A few turns of your cable through a ferrite choke may solve your problem. Hint: A ferrite choke chokes off the RF.
Part 15 devices are unlicensed and may emit low power radio signals on frequencies used by licensed services. Part 15 is the section of the FCC regulations dealing with unlicensed devices. Routers, cordless phones, weather stations, wireless printers, audio and video equipment are all Part 15 devices. Read the label on one.
The electrical part that opposes the flow of current in a DC circuit is called a resistor. Resistance is measured in ohms. Resistors have color-coded bands that tell their value.
Adjustable volume controls are potentiometers, variable resistors
Inductors are composed of a coil of wire. Inductors store energy in a magnetic field.
The ability to store energy in a magnetic field is called inductance.
The basic unit of inductance is the henry. The more inductance, the more henries. Remember “magnetic field, coils, henries, and inductance” go together.
Impedance is the measure of opposition to AC current flow. The higher the frequency, the more a given henry impedes the flow. The impedance is measured in ohms (just like DC). If you know the value in henries, you can calculate the amount of impedance for a given frequency. We’ll leave that math for the Extra Class license class test. Two or more conductive surfaces separated by an insulator, make up a capacitor. The ability to store energy in an electrical field is called capacitance. The electrical component that stores energy in an electrical field is called a capacitor. The basic unit of capacitance is called a farad . Remember “electrical field, farads, and capacitors” go together. The higher the frequency, the less impedance a capacitor provides. It is the opposite of the inductor.
Two or more conductive surfaces separated by an insulator, make up a capacitor. The ability to store energy in an electrical field is called capacitance.
The electrical component that stores energy in an electrical field is called a capacitor. The basic unit of capacitance is called a farad . Remember “electrical field, farads, and capacitors” go together.
A transistor is sometimes called a semiconductor. A component made of three layers of semiconductor material is a transistor.
Transistors are components capable of using a voltage or current to control current flow. A transistor can be used as a switch or an amplifier. Electronic components that can amplify signals are transistors . The term that describes a transistor’s ability to amplify a signal is called gain. The primary gain-producing component in an amplifier is a transistor. An FET is a special kind of transistor called a Field Effect Transistor.
The component that allows current to flow in only one direction is a diode. Diodes are also called rectifiers. The device or circuit that changes an alternating current to a direct current is a rectifier. That is their job in a power supply.
The two electrodes of a diode are called the anode and cathode. The anode is the positive side, and the cathode is negative. Hint: Remember “Annie and Cathy.”
The abbreviation LED stands for light emitting diode. An LED is commonly used as a visual indicator.
Voltage represents electromotive force . The unit of electromotive force is the volt. Think of Voltage as the pressure in the line. All that force can just sit there as it does in an electrical outlet. With nothing plugged in, the 120 volts are there, but not doing anything.
A circuit where the voltage is the same across all components is in parallel. Components that are side-by-side will all have the same pressure (voltage). Hint: That is why all your household electric outlets have the same voltage.
Amperes represent the current or amount of electricity flowing through the circuit. When you turn on a light, current flows through the wire and powers the bulb. Now, that voltage is pushing the current through the load (light bulb).
Components in series (end-to-end) will have the same current through each of them. The current flow is the same in each one. Hint: If you connect a small hose to a large hose, the same amount of water flows, but the pressure changes.
Ohm’s Law: Voltage = Amperes times Resistance. For this amazing feat, he got to name the unit of resistance after himself (ohm).
E symbolizes voltage (electromotive force). I is Amps or Amperage (flow). R is Resistance. Memorize that: VoltagE , Resistance, and the other one, Amps, I. So the formula for Ohm’s Law looks like E=IR.
So the formula for Ohm’s Law looks like E=IR. If you know two of the variables, you can calculate the third. The easy way is to use the magic circle and draw it as the Eagle flies over the Indian and the Rock.
The formula used to calculate current in a circuit is voltage divided by resistance. Hint: It asks for current, so cover the “I,” and the result is E divided by R.
The formula used to calculate voltage in a circuit is current multiplied by resistance. Hint: Cover the “E,” and the result is I time R.
The formula used to calculate resistance in a circuit is voltage divided by current . Hint: Cover the “R,” and the result is E divided by I.
Hint: When you take your test, the first thing you do is draw the magic circle on the back of the test sheet or scratch paper as allowed by the VE team. Don’t write in the test book as that is used again. When the Ohm’s Law question comes up, refer to your sketch.
The formula to calculate electrical power in a DC circuit is Power equals Voltage (E) multiplied by Current (I). It is easy as PIE, P=IE. We have another magic circle to help us. Hint: Copy it to the back of the test sheet as well.
Decibels are logarithmic (Power of 10) and relate to relative change. Going from 20 to 200 watts is 10 times or 10 dBs. Going from 200 watts to 2000 watts is another 10 db.
Since we are talking about logarithms, the change is not linear. Going from 5 watts to 10 watts is 3 dB . Doubling is 3 dB. It doesn’t matter where you start, if you double, it is 3 dB, and if you double again, it is 6 dB.
If you halve the power it is -3 dB. Halve the power again and it is -6 dB. A power decrease from 12 watts to 3 watts is -6 dB. Minus half, and minus half again.
A kilovolt would be one-thousand volts. Kilo is thousand. Mega is million. Giga is thousand million. Another way to specify a frequency of 1,500,000 hertz is 1500 kHz
A frequency display of 3.525 MHz is the same as 3,525 kHz. Hint: When going to a smaller identifier (MHz to kHz) change the period to a comma.
Radio and electronic soldering use rosin-core solder. Acid-core plumber’s solder would eat away the connection.
Multimeters measure voltage and resistance. They are very handy and some cost under $10. The cheap ones are not laboratory grade, but they will give accurate enough readings for most uses.
A half-wavelength antenna is half a wavelength long. The test question asks, “How long is a 6 meter half-wavelength dipole?” Six meters is a full wavelength, so 6 meters / 2 = 3 meters long for a half wave. That is a little over 9 feet x 12 = 112 inches is the closest answer.
Yagis, Quads, and Dishes are all directional antennas. They concentrate the signal in one direction and reject signals to the back and side of the antenna. A beam antenna concentrates signals in one direction . We call them “beams” because they beam the signal in one direction. A Yagi is a type of beam.
To locate the source of noise interference or jamming use radio direction finding. Use a directional antenna to get a bearing on the signal from two locations. The target is where the bearings cross on a map.
A directional antenna is also useful for a hidden transmitter hunt . This sport is also called fox-hunting. There are national and international fox-hunting competitions, but the fox doesn’t get hurt.
The characteristic impedance most often used for coax is 50 Ohms. It matches the normal impedance of a dipole installed over the ground.
Coaxial cable comes in many flavors. RG-58 and RG-8 are two popular types. The electrical difference between RG-58 and RG-8 coaxial cable is the RG-8 has less loss. Larger RG-8 cable will have less loss than smaller RG-58.
Use an antenna analyzer to determine if the antenna is resonant. By resonant, we mean how well the antenna matches to the frequency. You can also measure proper match with a directional wattmeter . It shows the forward and reflected power. You want to minimize the reflected power.
The standing wave ratio (SWR) is a measure of how well the load is matched . Reflected power is compared against forward power. Obviously, less reflected power is better. You want a low SWR in coaxial line to reduce signal loss.
A dummy load prevents transmission of signals over the air when making tests. We use a dummy load when we don’t want our signal to go out over the air.
A dummy load consists of a non-inductive resistor and heat sink. The resistor absorbs the transmitter current, and the heat sink dissipates the heat generated by power burned up in the resistor.
Rechargeable batteries include Nickel-metal hydride Lithium-ion Lead-acid gel cell. All choices are correct.
A mobile transceiver requires about 12 volts. Mobile transceivers use the same voltage as a car battery which is a nominal 12 volts.
A car can run on a full tank of gas for about 72 hours. If you ran the car a few hours a day to charge batteries, it could last for weeks. Consider your car as a source of energy in case of a power outage.