HAM - Radio Extra Class Test Radio Extra Class 1

Question 1

What is the input impedance of a quarter-wavelength transmission line section terminated with a short circuit?

Accepted Answer

Infinite impedance (open circuit)

Answer

A quarter-wave transmission line acts as an impedance inverter. A short circuit (0 Ω) at the far end appears as an open circuit (infinite impedance) at the input, and vice versa. This property is widely used in antenna matching networks and stub filters.

Question 2

Which filter design exhibits a maximally flat amplitude response throughout the passband, sacrificing roll-off steepness to eliminate ripple?

Accepted Answer

Butterworth

Answer

The Butterworth filter is specifically engineered for a 'maximally flat' passband — no ripple whatsoever. Chebyshev and elliptic filters achieve steeper roll-off at the cost of introducing passband or stopband ripple, while the Bessel filter prioritizes linear phase response.

Question 3

What is the lowest frequency in the 80-meter band at which an Extra class licensee may operate single-sideband phone?

Accepted Answer

3.600 MHz

Answer

FCC Part 97 grants Extra class licensees phone (including SSB) privileges beginning at 3.600 MHz on 80 meters, extending to 4.000 MHz. General class phone begins at 3.800 MHz, so Extra class has an additional 200 kHz of exclusive phone spectrum in the lower portion of the band.

Question 4

What does a receiver's third-order intercept point (IP3) specification describe?

Accepted Answer

The theoretical input power level at which third-order intermodulation products equal the fundamental signal amplitude

Answer

IP3 is a figure of merit for receiver linearity. It is the extrapolated input power where the third-order intermodulation products would theoretically reach the same level as the desired signals. A higher IP3 means the receiver handles strong nearby signals with less intermodulation distortion, which is critical in crowded band conditions.

Question 5

What is the approximate forward gain of a well-designed three-element Yagi antenna referenced to an isotropic radiator?

Accepted Answer

7 dBi

Answer

A three-element Yagi (driven element, reflector, and one director) typically achieves approximately 7 dBi (about 5 dBd) of forward gain. The reflector adds gain and improves front-to-back ratio, while the director narrows the forward lobe and boosts gain further.

HAM - Radio Extra Class Test Practice Test

HAM - Radio Extra Class Test Practice Test

HAM - Radio Extra Class Test Radio Extra Class 1