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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 *