GROL Amplifier and Oscillator Circuits 5

Question 1

An RF amplifier has an input signal of 2 mV and produces an output of 400 mV. What is the voltage gain?

Accepted Answer

200

Answer

Voltage gain = Vout / Vin = 400 mV / 2 mV = 200.

Question 2

A voltage gain of 100 expressed in decibels (dB) equals:

Accepted Answer

40 dB

Answer

Voltage gain in dB = 20 × log₁₀(100) = 20 × 2 = 40 dB.

Question 3

For maximum power transfer between an amplifier's output and the following stage, the source impedance should be:

Accepted Answer

Equal to the load (input) impedance of the following stage

Answer

The maximum power transfer theorem states that maximum power is delivered when the source impedance equals the load impedance — this is the principle behind impedance matching networks.

Question 4

The formula used to calculate the resonant frequency of a parallel LC tank circuit is:

Accepted Answer

f = 1 / (2π√(LC))

Answer

The resonant frequency is f = 1/(2π√LC), where L is inductance in henries and C is capacitance in farads; increasing either L or C lowers the resonant frequency.

Question 5

A high Q factor in a tuned tank circuit indicates:

Accepted Answer

Low energy loss per cycle with narrow bandwidth and high selectivity

Answer

The quality factor Q represents the ratio of energy stored to energy lost per cycle; a high Q means low loss, a sharp resonance peak, and narrow bandwidth.

(GROL) General Radiotelephone Operator License Practice Test

(GROL) General Radiotelephone Operator License Practice Test

GROL Amplifier and Oscillator Circuits 5