home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
HAM Radio 3.2
/
Ham Radio Version 3.2 (Chestnut CD-ROMs)(1993).ISO
/
exam
/
ext20
/
ext7.dat
< prev
next >
Wrap
Text File
|
1991-11-20
|
19KB
|
509 lines
294G-1C7 C 7-9 Not(1 OR 1) = 0|Not(1 OR 0) = 0|Not(0 OR 0) = 1
What is a NOR gate?
A. A circuit that produces a logic "0" at its output
only if all inputs are logic "0"
B. A circuit that produces a logic "1" at its output
only if all inputs are logic "1"
C. A circuit that produces a logic "0" at its output
if any or all inputs are logic "1"
D. A circuit that produces a logic "1" at its output
if some but not all inputs are logic "1"
*
295G-1C8 D 7-9 NOT bubble on output of OR gate|Left side drawn with curved line
What is the schematic symbol for an NOR gate?
| ┌─────── \ ┌───────\
A. ───┤ \ B. \ \
│ ├O── ───┤ \
───┤ / │ ├───
└─────── / ───┤ /
/ /
└───────/
┌───────\
│ \ \ \
C. │ \ D. ───┤ \
───O┤ ├──── │ ├O──
│ / ───┤ /
│ / / /
└───────/
*
296G-1C9 A 7-6 Inverter
What is a NOT gate?
A. A circuit that produces a logic "0" at its output
when the input is logic "1" and vice versa
B. A circuit that does not allow data transmission
when its input is high
C. A circuit that allows data transmission only
when its input is high
D. A circuit that produces a logic "1" at its output
when the input is logic "1" and vice versa
*
297G-1C10A 7-7 One input, one output|NOT bubble on output
What is the schematic symbol for an NOT gate?
| ┌───────\
│ \ \ \
A. │ \ B. ──O┤ \
────┤ ├O─── │ ├───
│ / ──O┤ /
│ / / /
└───────/
┌─────── \ ┌─────── \
C. ───┤ \ D. ──O┤ \
│ ├─── │ ├───
───┤ / ──O┤ /
└─────── / └─────── /
*
298G-1D1 C 7-6 Input Out.| 0 0 0| 1 0 1
What is a truth table?
A. A table of logic symbols that indicate the high logic
states of an op-amp
B. A diagram showing logic states when the digital device's
output is true
C. A list of input combinations and their corresponding
outputs that characterizes a digital device's function
D. A table of logic symbols that indicates the low logic
states of an op-amp
*
299G-1D2 D 7-9 High
In a positive-logic circuit, what level is used to represent
a logic 1?
A. A low level
B. A positive-transition level
C. A negative-transition level
D. A high level
*
300G-1D3 A 7-9 Low
In a positive-logic circuit, what level is used to represent
a logic 0?
A. A low level
B. A positive-transition level
C. A negative-transition level
D. A high level
*
301G-1D4 A 7-9 Low
In a negative-logic circuit, what level is used to represent
a logic 1?
A. A low level
B. A positive-transition level
C. A negative-transition level
D. A high level
*
302G-1D5 D 7-9 High
In a negative-logic circuit, what level is used to represent
a logic 0?
A. A low level
B. A positive-transition level
C. A negative-transition level
D. A high level
*
303G-2A1 D 7-12 A crystal oscillator is a high-stability|single frequency oscillitor. Its output|can be processed into reference signals
What is a crystal-controlled marker generator?
A. A low-stability oscillator that "sweeps" through a
band of frequencies
B. An oscillator often used in aircraft to determine
the craft's location relative to the inner and
outer markers at airports
C. A high-stability oscillator whose output frequency
and amplitude can be varied over a wide range
D. A high-stability oscillator that generates a series
of reference signals at known frequency intervals
*
304G-2A2 C 7-12 What type of circuit divides by two?
What additional circuitry is required in a 100-kHz
crystal-controlled marker generator to provide markers
at 50 and 25 kHz?
A. An emitter-follower
B. Two frequency multipliers
C. Two flip-flops
D. A voltage divider
*
305G-2B1 D 7-13 It divides a signal so that cheap|frequency counters can then count|and display the lower frequency
What is the purpose of a prescaler circuit?
A. It converts the output of a JK flip-flop to that of a RS
flip-flop
B. It multiplies an HF signal so a low-frequency counter can
display the operating frequency
C. It prevents oscillation in a low frequency counter circuit
D. It divides an HF signal so a low-frequency counter can display
the operating frequency
*
306G-2B2 A 7-13 A crystal oscillator is a high-stability|reference
What does the accuracy of a frequency counter depend on?
A. The internal crystal reference
B. A voltage-regulated power supply
C. Accuracy of the ac input frequency to the power supply
D. Proper balancing of the power-supply diodes
*
307G-2B3 B 7-12 Ten
How many states does a decade counter digital IC have?
A. 6
B. 10
C. 15
D. 20
*
308G-2B4 B 7-12 A decade counter digital IC divides an |input signal by 10, ie it produces one|output pulse for every ten input pulses
What is the function of a decade counter digital IC?
A. Decode a decimal number for display on a seven-segment
LED display
B. Produce one output pulse for every ten input pulses
C. Produce ten output pulses for every input pulse
D. Add two decimal numbers
*
309G-3A1 D 7-17 Gain and small size
What are the advantages of using an op-amp instead of LC
elements in an audio filter?
A. Op-amps are more rugged and can withstand more abuse
than can LC elements
B. Op-amps are fixed at one frequency
C. Op-amps are available in more styles and types than
are LC elements
D. Op-amps exhibit gain rather than insertion loss
*
310G-3A2 B 7-17 External components
What determines the gain and frequency characteristics of
an op-amp RC active filter?
A. Values of capacitances and resistances built into the
op-amp
B. Values of capacitances and resistances external to
the op-amp
C. Voltage and frequency of dc input to the op-amp power
supply
D. Regulated dc voltage output from the op-amp power
*
311G-3A3 D 7-17 Audio filters
What are the principle uses of an op-amp RC active filter
in amateur circuitry?
A. Op-amp circuits are used as high-pass filters to block
RFI at the input to receivers
B. Op-amp circuits are used as low-pass filters between
transmitters and transmission lines
C. Op-amp circuits are used as filters for smoothing power-
supply output
D. Op-amp circuits are used as audio filters for receivers
*
312G-3B1 C 7-18 Polystyrene
What type of capacitors should be used in an op-amp RC active
filter circuit?
A. Electrolytic
B. Disc ceramic
C. Polystyrene
D. Paper dielectric
*
313G-3B2 A 7-18 Restrict gain and Q
How can unwanted ringing and audio instability be prevented in
a multisection op-amp RC audio filter circuit?
A. Restrict both gain and Q
B. Restrict gain, but increase Q
C. Restrict Q, but increase gain
D. Increase both gain and Q
*
314G-3B3 D 7-19 In the low-level audio stages
Where should an op-amp RC active audio filter be placed in an
amateur receiver?
A. In the IF strip, immediately before the detector
B. In the audio circuity, immediately before the speaker or
phone jack
C. Between the balanced modular and frequency multiplier
D. In the low-level audio stages
*
315G-3B4 A 7-18 Bandpass
What parameter must be selected when designing an audio
filter using an OP-amp?
A. Bandpass characteristics
B. Desired current gain
C. Temperature coefficient
D. Output-offset overshoot
*
316G-4A1 D 7-20 Noise figure
What factors determine the sensitivity of a receiver?
A. Dynamic range and third-order intercept
B. Cost and availability
C. Intermodulation distortion and dynamic range
D. Bandwidth and noise figure
*
317G-4A2 A 7-21 Noise floor
What is the limiting condition for sensitivity in a
communications receiver?
A. The noise floor of the receiver
B. The power-supply output ripple
C. The two-tone intermodulation distortion
D. The input impedance to the detector
*
318G-4A3 B 7-20 Noise Floor = -174 + 10*Log(BW), BW in Hz|Noise Floor = -174 + 10*Log(400), Use F7|Noise Floor = -174 + 26 = -148 dBm
What is the theoretical minimum noise floor of a receiver with
a 400-Hertz bandwidth?
A. -141 dBm
B. -148 dBm
C. -174 dBm
D. -180 dBm
*
319G-4B1 B 7-22 Preselector
How can selectivity be achieved in the front-end circuitry of
a communications receiver?
A. By using an audio filter
B. By using a preselector
C. By using an additional RF amplifier stage
D. By using an additional IF amplifier stage
*
320G-4B2 B 7-22 SSB
A receiver selectivity of 2.4 kHz in the IF circuitry is optimum
for what type of amateur signals?
A. CW
B. SSB voice
C. Double-sideband AM voice
D. FSK RTTY
*
321G-4B3 D 7-22 Ringing during CW (A1A) reception
What occurs during CW reception if too narrow a filter bandwidth
is used in the IF stage of a receiver?
A. Undesired signals will reach the audio stage
B. Output-offset overshoot
C. Cross-modulation distortion
D. Filter ringing
*
322G-4B4 B 7-22 300 Hz for RTTY (F1B)
What degree of selectivity is desirable in the IF circuitry of
an amateur RTTY receiver?
A. 100 Hz
B. 300 Hz
C. 6000 Hz
D. 2400 Hz
*
323G-4B5 B 7-22 AM
A receiver selectivity of 10 kHz in the IF circuitry is optimum
for what type of amateur signals?
A. SSB voice
B. Double-sideband AM
C. CW
D. FSK RTTY
*
324G-4B6 B 7-22 2.4 kHz
What degree of selectivity is desirable in the IF circuitry of a
single-sideband phone receiver?
A. 1 kHz
B. 2.4 kHz
C. 4.2 kHz
D. 4.8 kHz
*
325G-4B7 B 7-21 Undesired signals
What is an undesirable effect of using too wide a filter bandwidth
in the IF section of a receiver?
A. Output-offset overshoot
B. Undesired signals will reach the audio stage
C. Thermal-noise distortion
D. Filter ringing
*
326G-4B8 A 7-21 Slightly greater then the|received-signal bandwidth
How should the filter bandwidth of a receiver IF section
compare with the bandwidth of the received signal?
A. Filter bandwidth should be slightly greater than the
received-signal bandwidth
B. Filter bandwidth should be approximately half the received-
signal bandwidth
C. Filter bandwidth should be approximately two times the
received-signal bandwidth
D. Filter bandwidth should be approximately four times the
received-signal bandwidth
*
327G-4B9 D 7-22 15 kHz for FM (F3E)
What degree of selectivity is desirable in the IF circuitry of
an emission FM phone receiver?
A. 1 kHz
B. 2.4 kHz
C. 4.2 kHz
D. 15 kHz
*
328G-4B10D 7-23 High-Q filter
How can selectivity be achieved in the IF circuitry of a
communications receiver?
A. Incorporate a means of varying the supply voltage to
the local oscillator circuitry
B. Replace the standard JFET mixer with a bipolar transistor
followed by a capacitor of the proper value
C. Remove AGC action from the IF stage and confine it to
the audio stage only
D. Incorporate a high-Q filter
*
329G-4C1 C 7-26 Largest tolerable/minimum discernible
What is meant by the dynamic range of a communications receiver?
A. The number of kHz between the lowest and the highest
frequency to which the receiver can be tuned
B. The maximum possible undistorted audio output of the
receiver, referenced to one milliwatt
C. The ratio between the minimum discernible signal and the
largest tolerable signal without causing audible distortion
products
D. The difference between the lowest-frequency signal and the
highest-frequency signal detectable without moving the
tuning dial
*
330G-4C2 D 7-26 Dynamic range
What is the term for the ratio between the largest tolerable
receiver input signal and the minimum discernible signal?
A. Intermodulation distortion
B. Noise floor
C. Noise figure
D. Dynamic range
*
331G-4C3 A 7-26 Cross-modulation|Desensitization
What type of problems are caused by poor dynamic range in a
communications receiver?
A. Cross-modulation of the desired signal and desensitization
from strong adjacent signals
B. Oscillator instability requiring frequent retuning, and
loss of ability to recover the opposite sideband, should
it be transmitted
C. Cross-modulation of the desired signal and insufficient
audio power to operate the speaker
D. Oscillator instability and severe audio distortion of all
but the strongest received signals
*
332G-4C4 B 7-26 Blocking dynamic range
The ability of a communications receiver to perform well in
the presence of strong signals outside the amateur band of
interest is indicated by what parameter?
A. Noise figure
B. Blocking dynamic range
C. Signal-to-noise ratio
D. Audio output
*
333G-4D1 C 7-20 Noise generated in the front end
What is meant by the term noise figure of a communications
receiver?
A. The level of noise entering the receiver from the antenna
B. The relative strength of a received signal 3 kHz removed
from the carrier frequency
C. The level of noise generated in the front end and succeeding
stages of a receiver
D. The ability of a receiver to reject unwanted signals at
frequencies close to the desired one
*
334G-4D2 C 7-20 RF stage, ie the front end
Which stage of a receiver primarily establishes its noise
figure?
A. The audio stages
B. The IF strip
C. The RF stage
D. The local oscillator
*
335G-5A1 A 7-14 Input and output signals are|180 degrees out of phase
What is an inverting op-amp?
A. An operational amplifier circuit connected such that the
input and output signals are 180 degrees out of phase
B. An operational amplifier circuit connected such that the
input and output signals are in phase
C. An operational amplifier circuit connected such that the
input and output are 90 degrees out of phase
D. An operational amplifier circuit connected such that the
input impedance is held at zero, while the output impedance
is high
*
336G-5B1 B 7-15 Input and output signals are in phase
What is an noninverting op-amp?
A. An operational amplifier circuit connected such that the
input and output signals are 180 degrees out of phase
B. An operational amplifier circuit connected such that the
input and output signals are in phase
C. An operational amplifier circuit connected such that the
input and output are 90 degrees out of phase
D. An operational amplifier circuit connected such that the
input impedance is held at zero, while the output impedance
is high
*
337G-5C1 D 7-14 For an inverting op-amp circuit|Gain = Rf / R1, Gain = 100K/1K|Gain = 100000/1000, Gain = 100
What voltage gain can be expected from the circuit in Figure 4BG-5
when R1 is 1000 ohms and Rf is 100 kilohms?
A. 0.01
B. 1
C. 10
D. 100
| ┌────/\/\/\/\/\/\───┐
│ Rf │
R1 │ / \ │
O────/\/\/\/\/\/\┴───┤ - \ │
│ \ │
│ ├─────┴───O
│ /
FIGURE 4BG-5 ┌───┤ + / O
│ \ / │
__│___ __│___
/ / / / / /
*
338G-5C2 C 7-14 For an inverting op-amp circuit|Gain = Rf / R1, Gain = 68K/1.8K|Gain = 68000/1800, Gain = 37.8
What voltage gain can be expected from the circuit in Figure 4BG-5
when R1 is 1800 ohms and Rf is 68 kilohms?
A. 1
B. 0.03
C. 38
D. 76
| ┌────/\/\/\/\/\/\───┐
│ Rf │
R1 │ / \ │
O────/\/\/\/\/\/\┴───┤ - \ │
│ \ │
│ ├─────┴───O
│ /
FIGURE 4BG-5 ┌───┤ + / O
│ \ / │
__│___ __│___
/ / / / / /
*
339G-5C3 B 7-14 For an inverting op-amp circuit|Gain = Rf / R1, Gain = 47K/3.3K
What voltage gain can be expected from the circuit in Figure 4BG-5
when R1 is 3300 ohms and Rf is 47 kilohms?
A. 28
B. 14
C. 7
D. 0.07
| ┌────/\/\/\/\/\/\───┐
│ Rf │
R1 │ / \ │
O────/\/\/\/\/\/\┴───┤ - \ │
│ \ │
│ ├─────┴───O
│ /
FIGURE 4BG-5 ┌───┤ + / O
│ \ / │
__│___ __│___
/ / / / / /
*
340G-5C4 C 7-14 For an inverting op-amp circuit|Gain = Rf / R1, Gain = 47000/10
What voltage gain can be expected from the circuit in Figure 4BG-5
when R1 is 10 ohms and Rf is 47 kilohms?
A. 0.00021
B. 9400
C. 4700
D. 2350
| ┌────/\/\/\/\/\/\───┐
│ Rf │
R1 │ / \ │
O────/\/\/\/\/\/\┴───┤ - \ │
│ \ │
│ ├─────┴───O
│ /
FIGURE 4BG-5 ┌───┤ + / O
│ \ / │
__│___ __│___
/ / / / / /
*
341G-5D1 D 7-17 Does not vary
How does the gain of a theoretically ideal operational amplifier
vary with frequency?
A. The gain increases linearly with increasing frequency
B. The gain decreases linearly with increasing frequency
C. The gain decreases logarithmically with increasing frequency
D. The gain does not vary with frequency
*
342G-6.1 C 7-29 Biasing network
What determines the input impedance in a FET common-source
amplifier?
A. The input impedance is essentially determined by the
resistance between the drain and substrate
B. The input impedance is essentially determined by the
resistance between the source and drain
C. The input impedance is essentially determined by the
gate biasing network
D. The input impedance is essentially determined by the
resistance between the source and substrate
*