Vacuum Tubes

71. What is the real measure of valve's amplification capability?

1. Plate resistance
2. Transconductance
3. Amplification factor
4. Gain

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72. What is the solid state equivalent of cold cathode diode?

1. Zener diode
2. LED
3. Varactor
4. Photodiode

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73. What is the solid state equivalent of thyratron?

1. FET
2. SCR
3. BJT
4. UJT

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74. What is the typical life span of an oxide coated emitter?

1. 500 hours
2. 200 hours
3. 1000 hours
4. 10000 hours

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75. What is the typical operating temperature of an oxide coated cathode?

1. 750°
2. 500°
3. 1200°
4. 1000°

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76. What is the typical plate efficiency of Class A amplifier?

1. 50 %
2. 75 %
3. 30 %
4. 10 %

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77. What is the typical value of ac plate resistance for a triode?

1. 1000 Ω
2. 100 kΩ
3. 1000 kΩ
4. 10 Ω

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78. What is the unit of transconductance?

1. Ohm
2. Siemen/m
3. Volt
4. Siemen

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79. What is the work function of an oxide coated cathode?

1. 4.0 electron-volts
2. 2.63 electron-volts
3. 4.52 electron-volts
4. electron-volts

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80. What operation results in severest distortion?

1. Class C
2. Class B
3. Class A
4. Class AB

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