M4 B2 Flashcards
What is done to an element to make it a semiconductor material?
The lattice of pure element is doped with elements that contain 3 or 5 valence electrons.
What is most commonly used as rectifiers in electrical circuits?
Diodes
When a PN junction is forward biased, the depletion zone …
narrows
The voltage applied to a reversed biased diode that causes the diode to breakdown and allow current flow is known as …
Avalanche Voltage
A typical application for Zener diodes is as …
Voltage regulators.
A rectifier Diode is used in applications that require … current
High
Name three dangers of diodes
Heat, over-voltage and over-current diodes.
A diode offers … to current flow which causes a … drop
- resistance
2.Voltage
A sillicon controlled Rectifier (SRC´s) use a … to control when current flow through the device
gate
UJT´s (unijunction) and FET´s(Field Effect) are types of …
Transistors
Complementary MOSFET(CMOS) devices are used to make … to build digital logic gates
transistors
What logic gate will provide an active high output only when all inputs are different?
Exclusive Or
The board of a printed circuit board is made of what material?
non-conductive
what is a conductive path on a printed circuit board is called
Trace
True or false
An open loop system uses feedback to ensure that controlled mechanisms have been moved to the proper position.
False. Closed loop systems have feedback, an open loop system does not.
Which describes the basic operation of a synchro system for
remote position indication?
1. A transmitter sends varying voltages to an indicator
motor which moves a pointer.
2. Resistances are compared in the transmitter and the
result is sent to the indicator motor to position a pointer.
3. A magnetic field in the transmitter is mirrored in the
indicator where a magnetic rotor aligns with the
magnetic field.
- A magnetic field in the transmitter is mirrored in the
indicator where a magnetic rotor aligns with the
magnetic field.
What three factors affect the amount of electricity that a capacitor can store?
Area of the plates, Distance of the plates and the Dielectric constant of the material between the plates.
The relationship between frequency and wavelength is …
inversely proportional
radio waves are directional and propagate out into space at …
186,282 miles per second (speed of light)
The electric field component and the … component of a radio wave are oriented 90° to each other, and at 90° to the direction that the wave is traveling
electromagnetic field
Ground waves or surface radio waves follow the curvature of the earth and are
low frequency waves
VHF communication radios are the primary communication radios used in aviation. They operate in what frequency range?
118.0 MHz to 136.975 MHz
To transmit and receive useful information, a radio wave is altered or modulated by …
an information signal
In an AM radio transmission, the radio wave is altered to carry useful information by modulating the …
Amplitude of the wave.
Since the transmitter oscillator output fluctuates during modulation to represent the information signal, FM bandwidth is
Greater than AM bandwidth
When two AC signals are mixed together, such as when a carrier wave is modulated by an information signal, three main frequencies result, what are they?
The original carrier wave frequency, the carrier wave frequency plus the modulating frequency, and the carrier frequency minus the modulation frequency.
what does radio transmitters and receivers or other electronic devices manipulate, resulting in the transmission of useful information through the atmosphere or space
they manipulate electricity
The basis of a transmitter in an precise … that creates an AC carrier wave frequency and amplifies it
oscillator
What isolates the desired carrier wave with its information
a receiver
What is a communication radio that transmits and receives?
A transceiver
Three characteristics are of major concern when considering antennas are?
Length, polarisation and directivity.
what can help make an antenna effectively shorter by being placed in series with the transmission line from the transmitter or receiver?
a capacitor
The electric field caused by the voltage in a conductor is parallel to the … of an antenna and is caused by the voltage difference between each end of the antenna
polarization
The three basic types of antennas used in aviation are the
Dipole, macron and loop antenna.
Transmission lines from transmitters to receivers are
coaxial cables
ADS-B stands for
Automatic dependent surveillance broadcast.
ADS-B OUT combines the positioning information available from … receiver with on-board flight status information. exp: location including altitude, velocity and time
GPS
Name 3 advantages of ADS-B over conventional ground-based radar
lower expense to cover entire airspace, more accurate,
weather dies not interferer with GPS signals
ELT stands for
Emergency Locator transmitter
An ELT is activated by excessive
G-forces
Second generation 406 MHz gidital ELT signals are loaded with …
GPS location coordinates
Any purposeful activation of an ELT signal by maintenance personnel is required to only be done
between the top of each hour and 5 minutes after the hour.
name 3 advantages to the 406 MHz ELT format over the original 121,5MHz system
Improved coverage
Improved location accuracy
Identification of false alerts
Shortened response times.
