Test Equipment (2018)

Question 1

Name one of the chief causes of test set failure.

Answer 1

Carelessness

Question 2

Although test equipment is repaired at the intermediate-level maintenance activity, most work performed at this level on test equipment consists of

Answer 2

Calibration

Question 3

What is the most delicate part of a piece of test equipment?

Answer 3

Meters

Question 4

List the basic measuring parameters of electronic equipment.

Answer 4

Voltage
Current
Resistance
Power
Frequency

Question 5

What is the most accurate portion of the ohmmeter scale, and why?

Answer 5

The midscale portion of the scale represents the most accurate area because the ohms-calibrated scale is nonlinear

Question 6

When repairing equipment, you should use a meter with the same sensitivity as specified in schematics and wiring diagrams. What is the reason for doing this?

Answer 6

Because of circuit loading, you should use a meter with the same sensitivity to obtain accurate readings.

Question 7

Name the piece of test equipment that consists of a hand-driven dc genera- tor, applies a high voltage to the com- ponent under test, and measures current leakage.

Answer 7

megohmmeter or megger

Question 8

Loading effect is the result of a meter’s sensitivity, and it causes incorrect voltage indications. What relationship exists between a meter’s sensitivity and its loading effect?

Answer 8

the lower the sensitivity of the meter, the greater the loading effect.

Question 9

What is the major difference between a VTVM and a conventional multimeter?

Answer 9

the VTVM uses a vacuum tube in its input

Question 10

A phase angle voltmeter is used to determine the overall accuracy of electronic equipment by measuring phase angles. What is actually measured by the phase angle voltmeter?

Answer 10

A phase measuring device must measure the phase difference between 2 discrete frequencies, regardless of the phase and amplitude to other components of the waveform.

Question 11

Describe the general function of a differential voltmeter.

Answer 11

Its general function is to compare an unknown voltage with an internal reference voltage and to indicate the difference in their values

Question 12

What item of test equipment is used to indicate the frequency of an external signal?

Answer 12

Frequency meter.

Question 13

List the parts of most heterodyne frequency meters.

Answer 13

A heterodyne oscillator, RF harmonic amplifier, crystal-controlled oscillator , a mixer or detector , a modulator , an AF output amplifier, and a means for indicating frequency.

Question 14

Wavemeters are calibrated resonant circuits used to measure frequency. List the three basic kinds of wavemeters.

Answer 14

Absorption, reaction, and transmission.

Question 15

Of the three basic wavemeters, which one is commonly used to measure microwave frequencies?

Answer 15

Transmission.

Question 16

The counter frequency meter is a high-speed electronic counter, with an accurate, crystal- controlled time base. What does this combination provide?

Answer 16

A frequency meter that automatically counts and displays the number of events (hertz) occurring in a precise interval.

Question 17

What does the Model 5245L counter frequency meter measure?

Answer 17

Frequency, period average, ratio of two frequencies, and total events.

Question 18

By what method is dc power determined?

Answer 18

P = IE

Question 19

You use a resistor that is specially designed to dissipate the required amount of power and replace normal loads. List the two types of resistors used for this purpose.

Answer 19

dummy loads

dummy antennas

Question 20

List the major sources of error that affect the overall accuracy of power measurements.

Answer 20

mismatch error
RF losses
instrumentation error

Question 21

The Huntron Trackers 1000 and 2000 are for use on circuit boards and systems with all voltage sources in what condition?

Answer 21

in the power off condition

Question 22

What mode on the automatic transistor analyzer Model 900 has the SonalertTM?

Answer 22

the SND mode

Question 23

What type signal display does the Huntron

Trackers 1000 and 2000 show when the signal fuse is open and the test leads shorted together?

Answer 23

displays short circuit signatures, even with the test leads open

Question 24

When using the Huntron Tracker 2000, why must you make good contact with the test leads?

Answer 24

because the test leads are conductive only at the tips.

Question 25

What is the minimum total shunt im- pedance across the junction of the diode or transistor under test using the automatic transistor analyzer Model 900 to ensure a good test reading?

Answer 25

not less than 270 ohms

Question 26

What is the principal function of the signal generator?

Answer 26

the production of an alternating voltage of the desired frequency and amplitude

Question 27

While various types of FM signal generators are available, many are restricted to special applications. What type is used for general applications?

Answer 27

the sweep generator

Question 28

Most frequency-swept signal generators use a reactance-tube method of modulation. What is the reason for this?

Answer 28

it results in greater flexibility, and the equipment is light and more compact.

Question 29

What is a common application for pulse- modulated generators?

Answer 29

checking receiver performance in radar systems that have a pulse-type emission

Question 30

Signal analyzers can be used in many applications. It is used for what function?

Answer 30

to check the response of an equipment under simulated conditions or specific operations

Question 31

What determination can you make by observing the square wave response?

Answer 31

whether the transmission of low or high frequencies is affected.

Question 32

An oscilloscope probe reduces the loading effect of the O-scope input circuit on the circuit under test. What is the second purpose of the probe?

Answer 32

to reduce the amount of signal voltage applied directly to the O-scope input connection

Question 33

The synchroscope is an adaption of the | oscilloscope. What is the difference of the trace on the synchroscope and oscilloscope?

Answer 33

a trace on the synchroscope is produced only when it is initiated by an input trigger; the O-scope has a continuous sawtooth sweep.

Question 34

Describe what factors a spectrum analyzer exhibits.

Answer 34

a spectrum analyzer is a device for exhibiting the spectrum of modulated waves in the radio-frequency range and microwave region

Question 35

Describe the purpose of the echo box.

Answer 35

it is used in field testing, troubleshooting and adjusting pulsed -type radar systems.

Question 36

What limitation should you consider when you use the echo box?

Answer 36

you need to remember that the echo box presents only relative rather than absolute values of power and sensitivity and only rough values of frequency.

Question 37

Describe some of the main uses for the TDR.

Answer 37

test sets are used to check and troubleshoot aircraft wiring, transmission lines, and antenna systems for shorts, opens, crimps, or bad couplings

Question 38

Describe the basics of TDR.

Answer 38

begins with the insertion of a step of pulse of energy into a system of cable. then, at the point of insertion, the energy reflected is observed.

Question 39

While you can determine different types of discontinuities with the TDR, what else can you determine through proper analysis?

Answer 39

you can determine if the discontinuity is resistive, inductive, or capacitive and whether it is in series or parallel with the load

Question 40

What factor determines the speed at which a wave travels through a transmission system?

Answer 40

the systems velocity constant; a wave travels through air faster than it does through polyethylene

Question 41

By what method does using a TDR help you locate an unacceptable connector?

Answer 41

TDR rapidly shows where mismatches are located; how bad they are; if they are resistive, capacitive, or inductive; and whether in series or shunt.

Question 42

While TDR and FDR provide similar measurements, the FDR eliminates what limitation of the TDR?

Answer 42

FDR checks cables at their actual operating frequencies, eliminating the limitation of TDR discontinuities outside the operating frequencies

Question 43

Describe the means by which the FDR identifies defective systems.

Answer 43

the FDR identifies defective systems by injecting an RF signal into a system and using insertion loss and return loss measurements to classify the system under these as good or in need of repair.

Question 44

When determining cable lengths or distance to faults, what means do you use to determine the number of feet from the cable end to the fault?

Answer 44

the resulting CRT display consists of a series of half-dome ripples. a count of the total number of these ripples multiplied by the calibration factor identifies the location of the fault

Question 45

List the elements of a typical VAST station.

Answer 45

a computer subsystem, a data transfer unit, and a stimulus and measurement section that contains functional building blocks configured to meet the intended test applications

Question 46

List the three levels of detection that ensure rapid confidence tests and easy fault detection.

Answer 46

auto-check self-check self-test

Question 47

What is the purpose of programmed halts?

Answer 47

to allow manual intervention during the course of testing to make adjustments and observations.