Definitions of Technical Terms 2018

Terms / Definitions
Ammeter /
  • Howis an ammeter usually connected… = In series with the circuit
  • Whatinstrument is used to measure electric current? = An ammeter
  • Ammetercalibrated in amperes used to measure a 3000-milliampere current = readingshows 3 amperes

Amperes, Amps /
  • Electricalunit of current
  • Intensityof the movement of charge in a conductor
  • SeeOhm’s Law questions.

Band /
  • What property ofradio waves is often used to identify the different frequency bands? = Theapproximate wavelength

Bandwidth /
  • How wide a signal is, or how much room it takes up. FM voice signals have a larger bandwidth than SSB signals, and CW signals are narrower than SSB.

Battery /
  • Component 4 in figure T1
  • Stores energy chemically
  • Rechargeable types: Nickel-metal hydride, Lithium-ion, Lead-acid gel-cell
  • Not rechargeable type: Carbon-zinc
  • Shorting the terminals can cause burns, fire, or an explosion

Capacitor /
  • Storesenergy in an electric field
  • Consistsof two or more conductive surfaces separated by an insulator
  • Usedtogether with an inductor to make a tuned circuit
  • Unitof capacitance is the Farad or microfarad
  • Whatkind of hazard might exist in a power supply when it is turned off anddisconnected? = Electric shock from stored charge in large capacitors
  • Component6 in figure T2

Carrier Squelch /
  • Muting receiveraudio solely by the presence or absence of an RF signal

Diode
/
  • Allows currentto flow in only one direction
  • Cathode leadusually identified? = With a stripe
  • Names of theelectrodes of a diode = Anode and cathode

Dipole /
  • Simpledipole mounted so the conductor is parallel to the Earth’s surface = Ahorizontally polarized antenna
  • Changea dipole antenna to make it resonant on a higher frequency? = Shorten it
  • Approximatelength, in inches, of a 6 meter ½ wavelength wire dipole antenna? = 112
  • Approximate length, in inches, of a quarter-wavelength vertical antenna for 146MHz? = 19
  • Inwhich direction is the radiation strongest from a half-wave dipole antennain free space? = Broadside to the antenna

Doppler shift /
  • An observed change in signal frequency caused by relative motion between the satellite and the earth station

Electromagnetic /
  • Type of wavethat carries radio signals between transmitting & receiving stations
  • Usual name forelectromagnetic waves that travel through space = Radio waves

Farad /
  • Basic unit ofcapacitance

Frequency /
  • #of times alternating current flows back & forth in one second
  • Hz= one time per second (or one cycle per second)
  • 300/(Wavelengthin meters) = Frequency in MHz

Fuse /
  • Purpose= To interrupt power in case of overload
  • Unwiseto install a 20ampere fuse in the place of a 5-ampere fuse = Excessivecurrent could cause a fire
  • Safetyequipment should always be included in home-built equipment that is poweredfrom 120V AC power circuits = a fuse or circuit breaker in series with theAC “hot” conductor
  • Whatelectrical component is used to protect other circuit components fromcurrent overloads? = Fuse

Hertz /
  • Unitof frequency
  • Onecycle per second
  • Whatis the formula for converting frequency to wavelength in meters? = Wavelengthin meters equals 300 divided by frequency in megahertz
  • Whatis another way to specify a radio signal frequency of 1,500,000 hertz? =1500 kHz
  • Ifa frequency readout calibrated in megahertz shows a reading of 3.525 MHz,what would it show if it were calibrated in kilohertz? = 3525 kHz

Inductance,
Inductor /
  • Storesenergy in a magnetic field
  • Basicunit of inductance = The Henry
  • Usuallycomposed of a coil of wire
  • Component3 in figure T3
  • Usedtogether with a capacitor to make a tuned circuit

LED /
  • LightEmitting Diode
  • Component8 in figure T2

Meters /
  • Wavelength
  • 300/(Frequencyin MHz) = Wavelength in meters

microfarad /
  • 1,000,000picofarads = 1 microfarad

microvolt /
  • Oneone-millionth of a volt
  • How many voltsare equal to one kilovolt? = One thousand volts
  • How many volts
  • are equal to one microvolt? = One one-millionth of a volt

milliampere /
  • 1/1000Ampere
  • 1.5amperes = 1,500 milliamperes

Ohms /
  • Resistance
  • Impedanceof most commonly used coaxial cable in typical amateur radio installations =50 ohms
  • SeeOhm’s Law questions

Oscillator /
  • The name of a circuit that generates a signal at a specific frequency

Picket Fencing /
  • Rapidfluttering sound from mobile stations moving while transmitting

picofarad /
  • 1,000,000picofarads = 1 microfarad

Potentiometer /
  • Adjustablevolume control
  • Controlselectrical parameter of Resistance

Radio Waves /
  • Electromagneticwaves change direction greater than 20,000 times/second
  • Travelsspeed of light, 300 million meters/second

Rectifier /
  • Changesalternating current to varying direct current signal

Relay /
  • An electrically-controlled switch

Resistance /
  • Opposethe flow of current in a DC circuit
  • SeeOhm’s Law questions

Resistor /
  • Opposes flow ofcurrent in DC Current

Single Sideband /
  • Formof amplitude modulation
  • SSB
  • Normallyused for 10 meter HF, VHF and UHF single-sideband communications = Uppersideband
  • Primaryadvantage of single sideband over FM for voice transmissions? = SSB signalshave narrower bandwidth
  • Approximatebandwidth of a single sideband voice signal? = 3 kHz
  • Controlcould be used if the voice pitch of a single-sideband signal seems too highor low? = The receiver RIT or clarifier
  • Typeof voice modulation most often used for long-distance or weak signalscontacts on the VHF and UHF bands

Squelch Control /
  • Mute receiveroutput noise when no signal is being received

Transistor /
  • Componentcapable of using voltage or current signal to control flow
  • Electronicswitch or amplifier
  • Threelayers of semiconductor material? = Bipolar junction transistor
  • Whichof the following electronic components can amplify signals? = Transistor
  • Whatdoes the abbreviation “FET”standfor? = Field
  • effect transistor
  • Whatis the term that describes a transistor’s ability to amplify a signal? =Gain
  • Whichsemiconductor component has a gate electrode? = Field effect transistor
  • Component2 in figure T1

UHF and VHF /
  • VeryHigh Frequency, Ultra High Frequency
  • Radiationtype is non-ionizing
  • Whichof the following types of feedline has the lowest loss at VHF and UHF? =Air-insulated hard line
  • Whyare UHF signals often more effective from inside buildings than VHF signals?= The shorter wavelength allows them to more easily penetrate the structureof buildings
  • Whatantenna polarization is normally used for long-distance weak-signal CW andSSB contacts using the VHF and UHF bands? = Horizontal
  • Whatcan happen if the antennas at opposite ends of a VHF or UHF line of sightradio link are not using the same polarization? = Signals could besignificantly weaker.
  • Whatmay occur if VHF or UHF data signals propagate over multiple paths? Errorrates are likely to increase
  • Whyare “direct” (not via a repeater) UHF signals rarely heard from stationsoutside your local coverage area? = UHF signals are usually not reflected bythe ionosphere
  • Whatmode is responsible for allowing over-the-horizon VHF and UHF communicationsto ranges of approximately 300 miles on a regular basis? = Troposphericscatter
  • Whydo VHF and UHF radio signals usually travel somewhat farther than the visualline of sight distance between two stations? = The Earth seems less curvedto radio waves than to light.

Volts /
  • Basicunit of electromotive force (EMF) that causes electron flow
  • Lowestvoltage that can cause a dangerous electric shock? = 30 volts
  • Howmany volts are equal to one kilovolt? = One thousand volts
  • Howmany volts are equal to one microvolt? One one-millionth of a volt
  • Whichinstrument would you use to measure electric potential or electromotiveforce? = A voltmeter
  • Whatis the correct way to connect a voltmeter to a circuit? = In parallel withthe circuit
  • Whichof the following might damage a multimeter? = Attempting to measure voltagewhen using the resistance setting
  • SeeOhm’s Law questions

Watt /
  • Electricalpower is measured in Watts
  • Power(Watts) = Volts times Amps
  • P =E x I
  • Maximumpower level that an amateur radio station may use at frequencies above430MHz before an RF exposure evaluation is required = 50 Watts PEP at theantenna
  • Equivalentto 500 milliwatts? = 0.5 watts
  • Maximumpower allowed when transmitting telecommand signals to radio controlledmodels? = 1 watt

Wavelength /
  • Distanceradio wave travels in one complete cycle
  • Measuredin meters
  • Howdoes the wavelength of a radio wave relate to its frequency? The wavelengthgets shorter as the frequency increases
  • Wavelengthin meters equals 300 divided by frequency in megahertz
  • Bandsare named by wavelength: 1.25m, 2m, 6m, etc.
  • Whatproperty of radio waves is often used to identify the different frequencybands? = The approximate wavelength
  • Whatis the approximate length, in inches, of a quarter-wavelength verticalantenna for 146 MHz? = 19
  • Whatis the approximate length, in inches, of a 6 meter ½-wavelength wire dipoleantenna? = 112

Goodkin Radio Class © 2018

C:\Users\Norm\Dropbox\Amateur Radio\ham classes\FAQs Tech Exam 2018-2022\Definitions of Technical Terms 18.docx[Type here] 1