Module 7.4 Flashcards
What is a dynamometer?
A device designed for power measurement
What energises the moving coil in a dynamometer?
Voltage
What energises the stationary coil in a dynamometer?
Current
How is the moving coil connected in the circuit?
In series with a range resister so that the full load voltage is not applied to it
How is a wattmeter rated?
In volts and amperes
How does a frequency meter work?
A parallel inductor and capacitor in the form of a tank circuit
What is measured in a frequency meter?
Maximum amplitude of voltage across the inductor and capacitor
When is the frequency read from a meter?
When the device has been adjusted for maximum indication on the meter
The capacitor in a frequency meter is variable with
adjustment knob and calibrated in Hertz
What does a frequency counter comprise of?
An accurate clock
A gate circuit
A digital counter
An LCD display
Frequency counters work by
dividing the number of pulses by the time the gate was open
How can the frequency range of a counter be increased?
By adding a prescaler between the signal input and the counter
Frequency counters measure up to 1 GHz. The speed is set by
the maximum speed of the digital logic
What can oscilloscopes be used for?
Displaying time related wave forms
Frequency measurements
Voltage measurements
The oscilloscope works by
Electron gun which projects a stream of electrons between deflecting plates into a phosphorescent coated screen
What does the oscilloscope illumination depend on?
The quantity of electrons and their velocity in impact with the screen
When is a low range pitot static leak test carried out?
Every time the pitot or static system is disturbed
If there is a suspicion of a leak in a low range test what should happen next?
A full range leak check
What is required for a pitot static leak test?
A calibrated ASI and a hand pump as well as a vacuum
What is used for a high range pitot static leak test?
Air data test set
What can an air data test set be used for?
High range leak test
Calibration of instruments
ATC and Mode C altitude report test
What makes up an air data test set?
A pressure pump
Vacuum pump
Altimeter
VSI
ASI
How is the moving coil of a dynamometer connected
In series with a range resistor so the full voltage is not applied
The horizontal coil of wire in a dynamometer measures what?
Load current
What does the frequency meter indicate?
Maximum amplitude of voltage across two components
What is the frequency counter adjustment knob calibrated to?
Resonant frequency for any given setting
In oscilloscopes -
The intensity of the illumination depends on what?
The quantity of electrons in the stream and their velocity on impact with the screen
In oscilloscopes -
The potential at G1 of the CRT in an oscilloscope is negative. What controls the brightness of the illuminated spot?
Adjusting the R1 resistor
In oscilloscopes -
G2 and G3 enables the electron stream to be focused at the screen
Positive potential difference
In oscilloscopes - The position of the spot on the screen is determined by
the simultaneous effect of voltages applied to the X and Y deflecting plates
