Description : Technical manuals for tape recorders can state the SNR in what three different ways?
Last Answer : a. Root-mean-square (RMS) signal-to-RMS noise. b. Peak-to-peak signal-to-RMS noise. c. Peak signal-to-RMS noise.
Description : What type of reeling system best controls a tape recorder's tape tension during starts and stops?
Last Answer : A tape buffering reeling system
Description : What are the four basic parts of a magnetic tape recorder's tape transport system?
Last Answer : a. Tape reeling system. b. Tape speed control system. c. Electronic subsystem. d. Basic enclosure.
Description : What causes flutter in a tape recorder’s output?
Last Answer : Non-uniform tape motion caused by variations in tape speed.
Description : What number harmonic is the primary harmonic distortion in magnetic tape recorders?
Last Answer : Third-order harmonic.
Description : List four factors that can degrade the frequency response of magnetic tape recorders.
Last Answer : a. A too-high or too-low bias signal level setting for the record head. b. An improper reproduce head gap. c. An improper tape transport speed. d. Poor tape-to-head contact.
Description : Two tape recorders have signal-to-noise ratios (SNRs) of 25-dB RMS and 35-dB RMS respectively. Which of the SNRs can record and reproduce the widest range of input signals and why?
Last Answer : 35-dB RMS because the highest SNR can always record and reproduce the widest range of input signals.
Description : The head driver circuit of a tape recorder’s FM record electronics (figure 5-4) performs what function?
Last Answer : It amplifies the frequency-modulated output from the record oscillator and sends it to the record head.
Description : The equalization and phase correction circuit in a tape recorder’s direct reproduce electronics (figure 5-2) performs what function?
Last Answer : It generates an equalization signal which corrects any frequency response problems in the input signal from the pre-amplifier circuit.
Description : The head driver circuit in a tape recorder’s direct record electronics component (figure 5-1) performs what function?
Last Answer : It takes the signal from the summing network, amplifies it, and sends it to the record head for recording.
Description : What two types of record and reproduce electronics are used by magnetic tape recorders?
Last Answer : . a. Direct record (AM). b. Frequency modulation (FM).
Description : Magnetic tape recorders can have up to three different heads installed. What are the three functions performed by a recorder's heads?
Last Answer : Record, reproduce, and erase.
Description : What method for erasing magnetic tape is much more effective and reliable than using a recorder’s erase head?
Last Answer : Using a magnetic tape degausser
Description : What are two disadvantages of using a recorder’s erase head to erase data recorded on a magnetic tape?
Last Answer : Using an erase head is slow, and it may not completely erase the tape.
Description : After using a tape that was stored in an area where temperatures exceeded 130º F you notice pieces of oxide sticking to the recorder's tape-transport mechanism, to its magnetic heads, and onto the tape. What is the probable cause of these symptoms?
Last Answer : Oxide shedding. At temperatures above 130º F, oxide coating becomes soft and sheds.
Description : Digital magnetic tape recorders used to store and retrieve digital data fall into what three categories?
Last Answer : a. Computer-compatible digital tape recorders. b. Telemetry digital tape recorders. c. Instrumentation digital tape recorders
Description : Which digital data encoding method helps overcome a tape recorder’s low-frequency response problems by recording two logic levels for each incoming data bit?
Last Answer : Bi-phase level encoding.
Description : What type of equipment should you use to demagnetize your recorder's magnetic heads?
Last Answer : A hand-held degausser like the manual degaussers used for degaussing magnetic tape.
Description : Which performance parameter is the minimum amount of optical power required to achieve a specific bit-error rate (BER) in digital systems or a given signal-to-noise ratio (SNR) in analog systems?
Last Answer : Receiver sensitivity.
Description : Why does adding dc vice ac bias voltage to the input signal result in a poor signal-to-noise ratio (SNR)?
Last Answer : With dc bias, the SNR is poor because only a small portion of the magnetism curve is straight enough to use, thus the output signal is weak compared with the natural tape hiss.
Description : What test equipment is designed to generate, modify, or measure a range of parameters of electronic functions of a specific nature required to test a single system or equipment?
Last Answer : Special-purpose electronic test equipment.
Description : Which single phase ac motor will you select for record players and tape recorders? a) Hysteresis motor b) Shaded pole motor c) Reluctance motor d) Two value capacitor motor
Last Answer : Which single phase ac motor will you select for record players and tape recorders? Hysteresis motor
Description : What equipment should you use to de-magnetize a magnetic tape transport?
Last Answer : A hand-held degausser.
Description : A recorder’s harmonic-distortion specification reads 2% third harmonic of a 100-kHz signal at 60 ips. What does this mean?
Last Answer : The recorder has 2% third-harmonic distortion of a 100-kHz signal at 60 ips.
Description : How often should you demagnetize a recorder's magnetic heads?
Last Answer : Every 8 to 25 hours depending on the manufacturer's recommendations.
Description : How should you clean your recorder's magnetic heads?
Last Answer : With a cotton-tipped applicator soaked in either isopropyl alcohol or a head cleaner recommended by the recorder's manufacturer.
Description : A recorder's erase head is always placed in what sequence on the record/reproduce track?
Last Answer : . First, before the record and reproduce heads.
Description : Why are record heads always placed before reproduce heads on recorders?
Last Answer : Allow you to monitor the signals you're recording.
Description : What two specifications determine the maximum frequency that a recorder's record and reproduce heads will be able to transfer?
Last Answer : a. Size of the headgap. b. Speed of the magnetic tape.
Description : Air gap readings should be periodicly taken for electrical generation equipment. The best tool to use to take these measurements is a ___________. A. cloth (non-metalic) tape measure B. dial indicator C. inside micrometer D. tapered, long blade, feeler gage
Last Answer : Answer: D
Description : What equipment uses a calibrated resonant circuit to measure frequency?
Last Answer : Wavemeter.
Last Answer : The full form of SRN is Signal-to-noise ration.
Description : To avoid objectionable noise in a microwave TV link, the SNR should be about:
Last Answer : 25 or more
Description : SNR is: A. Signal to Noise Ratio B. Signal to Net Ratio C. Signal to Noise Rate D. None of above
Last Answer : A. Signal to Noise Ratio
Description : The threshold effect in demodulators is a) The rapid fall of output SNR when the input SNR falls below a particular value b) Exhibited by all the demodulators when the input SNR is low c) Exhibited by all AM suppressed carrier coherent demodulators d) Exhibited by correlation receivers
Last Answer : The threshold effect in demodulators is The rapid fall of output SNR when the input SNR falls below a particular value
Description : The capacity of a standard 4 KHz telephone channel with a 32 dB SNR is
Last Answer : The capacity of a standard 4 KHz telephone channel with a 32 dB SNR is 32953 bits/second
Description : What calibration label is used when actual measurement values must be known to use the test equipment?
Last Answer : CALIBRATED—REFER TO REPORT.
Description : Name the two classes of test equipment.
Last Answer : General-purpose electronic test equipment (GPETE) and special-purpose electronic test equipment (SPETE).
Description : What system is currently used by all branches of the military to identify test equipment?
Last Answer : Joint Electronics Type Designation System (JETDS).
Description : NELAT and VAST are examples of what type of test equipment?
Last Answer : Off-line.
Description : What test equipment continuously monitors electronic systems?
Last Answer : On-line.
Description : List the three groups of test equipment used for fault isolation in 2M repair.
Last Answer : On-line, off-line, and General Purpose Electronic Test Equipment (GPETE)
Description : Why should you avoid using ac-powered test equipment when wearing a wrist strap?
Last Answer : For your own safety.
Description : The frequency response of test equipment refers to what aspect of ac voltage measurements?
Last Answer : the range of frequencies that can accurately be measured.
Description : The input impedance of your test equipment should exceed the impedance of the circuit under test by what ratio?
Last Answer : 10 to 1
Description : What assures the accuracy of your electronic test equipment?
Last Answer : Its calibration.
Description : What amount of flat tape or round cord is required to single lace a group of conductors?
Last Answer : Two and one-half times the length of the longest conductor in the group.
Description : Why is flat tape preferred instead of round cord when wire bundles are laced?
Last Answer : Round cord has a tendency to cut into the wire insulation.
Description : Why is friction tape used in splicing?
Last Answer : As a protective covering over the rubber tape.
Description : When cleaning the parts of a tape transport, why should you switch lint-free cloths and swabs often?
Last Answer : You may transfer dirt or oxide particles from one part of the tape transport to another