Avionics Flashcards: Volume 2 - Pt.1
Card Set Information
Avionics Flashcards: Volume 2 - Pt.1
201-215 Self-Test Questions.
Define "triboelectric effect."
The production of an electrostatic charge by friction.
How does higher humidity reduce the ESD danger?
It keeps surfaces moist, thereby increasing the conductivity of the surfaces.
What is the desirable humidity level for ESD protective areas?
How does mounting a component on a circuit board affect the ESD susceptibility?
Doesn't reduce susceptibility.
Which ESDS items must be handled at an approved, static safeguarded workstation?
Why do reparable items require ESD protective packaging?
So no further ESD damage is done to the remaining operating parts of the item being handled.
Define the term static dissipative material.
Provides a static drain fast enough to remove the static charge quickly before any damage is done and slow enough to not produce a damaging discharge current.
Explain what could occur if you sprayed an anti-stat on a circuit board and why.
Circuit malfunctions could occur because of leakage paths formed by the anti-stat.
What are the three principal components of any ESD control workstation?
1. Static dissapative work surface
2. Personnel wrist strap (cuff and cord)
Why should you roll up your long shirt sleeves when working at an ESD control workstation?
This reduces the chances of triboelectric charges developing.
What can you use in an AC outlet to ground ESD control workstations?
The outlet mounting screws.
Can you wear a wrist strap while working on energized equipment?
Describe the proper wear of a personnel wrist strap.
The cuff is worn snug to the wrist, with no clothing between the cuff and your skin. Adjust the strap when necessary to ensure a snug fit.
How often must wrist straps be checked to see if they are functional?
What can you do to improve wrist strap conductivity if you have dry skin?
Use hand or moisturizing creams to obtain better electrical continuity between the wrist strap and wrist.
What is used to test the integrity of the entire wrist strap system?
Wrist strap tester.
When must you wear static dissipative garments?
When handling super-sensitive devices.
What are the units of force when you're developing torque?
Ounces, pounds, grams, and kilograms.
What are the units of distance when you're developing torque?
Inches, feet, millimeters, and meters.
How are the magnitudes of torque most commonly experessed?
Inch-pounds and foot-pounds.
Describe the four types of torque wrenches.
1. Type I - deflecting needle on a fixed scale
2. Type II - uses a dial and indicator
3. Type III - micro-meter like adjustment sleeve
4. Type IV - nonadjustable; preset torque
What's the purpose of balanced torquing sequence?
To prevent warping the assembly being torqued.
When are torque requirements met?
When the minimum torque value is reached.
Under what circumstances should you use a torque wrench to break loose a bolt?
What should you do if you've over-torqued a bolt?
Loosen the bolt and start again.
What fastening device is normally associated with prevailing torque?
Self-locking nuts and screws.
When must you compensate for prevailing torque?
When required by the technical data.
You're preparing to torque a nut to 120-inch-pounds using an extension. What information do you need to find the torque setting?
The length of the torque wrench and the effective length (the length of the torque wrench plus its extension).
Compute the modified torque value for 120-inch-pounds of recommended torque using a 12-inch torque wrench with an 8-inch extension.
What must you do if you drop a calibrated torque wrench?
Have the wrench calibrated before it's used again.
Where can you find guidelines for tool management?
AFI 21-101 and local supplements or policies.
What is TAS?
An Automated Tool Accountability System.
What information can you get from TAS?
The status for a CTK, such as a ll tools are serviceable, tools that are removed for calibration, tools that are broken, removed, and or ordered.
What do you use to inventory a CTK?
A printout of the MIL from TAS.
Where do you document that a tool was removed from a CTK?
In TAS and all of the copies of the MIL.
What is the purpose of the EID?
To identify the base, unit, shop, and CTK that a tool belongs to.
Describe amplitude modulation.
The amplitude of the carrier is varied to represent some sort of information.
What happens in mixing?
Two waveform are combined and two new frequencies are created, the upper side-band and the lower side-band.
What is the process of removing the intelligence from the carrier?
When is it more efficient to use pulse amplitutde modulation?
When using a carrier greater than 1,000 MHz.
What frequency bands are used with pulse amplitude modulation?
Super high frequency and extremely high frequency.
For what is a directional coupler used?
To sample the input signal without the need for moving parts or adjustments.
What are the outputs of a mixer?
There are four output signals. The two original inputs, and the sum and difference of the two inputs.
How does a power divider affect the power and frequency characteristics of a signal that passes through it?
The power is cut in half, but the frequency stays the same.
What is the purpose of an isolator?
Normally to isolate two separate circuits or prevent any feedback in the circuit.
How do you identify what type of filter is shown in a schematic?
By the placement of the slash marks across the wavy lines.
What is the difference between a fixed attenuator and a programmable attenuator?
Fixed attenuator provides contrast attenuation.
Programmable attentuator provides variable attenuation.
What are at least three of the units that can be displayed by the power meter?
6. dB (REL)
How do you use the relative power measurement mode for frequency response testing?
You set the dB (REF) for the transmitter under test, and then monitor any changes in power at different frequencies or settings.
In general terms, what does a power sensor do?
Changes energy from one form into another form.
What are some of the older power sensors?
Bolometers, calorimeters, thermistors, and thermocouples.
What are some of the advantages of a diode detector over a thermistor mount?
Higher sensitivity, reduced noise, less frequency drift, and a lower SWR.
How much more efficient is a detecting diode than a thermistor?
What device determines the power measurement range of a power meter?
The power sensor.
What must you do before you can use the power meter/power sensor system?
Marry (calibrate) them togther as a system.
Why should you not twist a power sensor when installing it?
You may cause major damage to the power sensor's internal circuits.
What is the basic RF power measurement?
What must you do before turning ON the power meter?
Make sure it's set to match the line voltage you're using.
After you've turned the power meter on, what's the first task you must do?
Zero the power sensor.
How much RF input is allowed when zeroing the power sensor?
What happens when you press the dB (REF) switch a second time?
Enters a new reference level.
When taking measurements of a signal, should you make the signal as high and wide as possible, or as short and narrow as possible?
As high and wide as possible.
At what percentage amplitude points do you measure the rise time of a pulse?
Between the 10 percent and 90 percent amplitude points on the leading edge of the pulse.
How much faster should the vertical system of your scope be than the rise time of the applied signal?
2 to 5 times.
At what amplitude point is the time interval measurement taken on the width of a pulse?
The 50% amplitude point of the pulse.
What is the formula for converting time to frequency?
What is the frequency range of the typical spectrum analyzer?
9 kHz to 26.5 GHz.
What must be done to the spectrum analyzer before making measurements?
It must be calibrated.
What piece of test equipment is used to self-calibrate RF devices within systems or test stations?
Generally speaking, what does a counter do?
It accumulates, from an applied signal, input pulses in binary form, and then converts them to decimal form for a digital readout.
What are the basic measurement functions of the universal counter?
Frequency, period, time, totalize, and volts.
What are the most accurate, convenient, and flexible instruments available for making frequency and time interval measurements?
Electronic frequency counters.
What are the five operating modes of the pulse generator?
4. External width
5. External burst
What determines the number of pulses output in EBUR mode?
The parameter valves set by the RANGE/VERNIER rocker switches.
How many control modes can be selected?
What sweeper keys are used to select specific frequency and power levels?
What key selects special functions?
What frequency must the start frequency be, in comparison with the stop frequency?
Must be 100 MHz lower.
What does the CF key select?
What does the ΔF key select?
Frequency span for the center frequency.