Free Ham Radio Technician Amateur Questions and Answers

Question 1

How does a fast-scan (NTSC) television system produce an interlaced scanning pattern?

Accepted Answer

By scanning odd numbered lines in one field and even numbered lines in the next

Answer

Explanation:
In a fast-scan (NTSC) television system, an interlaced scanning pattern is generated by scanning the odd numbered lines in one field (1/60th of a second) and then the even numbered lines in the next field. This process is repeated to create a complete video frame (2 fields), resulting in 60 interlaced fields per second (or 30 complete frames per second). The interlaced scanning pattern was developed to help reduce the flicker and improve the perceived motion in television images, while also conserving bandwidth.

Question 2

In a push-pull Class AB amplifier, how long does each active component operate throughout a signal cycle?

Accepted Answer

More than 180 degrees but less than 360 degrees

Answer

Explanation:
Each active element in a push-pull Class AB amplifier conducts for slightly more than 180 degrees but less than 360 degrees of the signal cycle.

Question 3

What does it mean when a transmitter is set to resonance, and the current reading on an RF ammeter connected in series with the antenna feed line rises?

Accepted Answer

There is more power going into the antenna

Answer

At resonance, a rising current on an RF ammeter in series with the feed line means more power is actually being delivered into the antenna, indicating efficient energy transfer. A short to ground, poor neutralization, or an impedance mismatch would instead cause abnormal readings or reflected power rather than the clean increase in feed-line current that signals proper power transfer.

Question 4

What causes a junction diode to fail when there is too much current flowing through it?

Accepted Answer

Excessive junction temperature

Answer

Explanation:
Excessive current causes an increase in temperature in the diode junction, which can ultimately lead to thermal runaway and device failure.

Question 5

Which best defines a Pi-L-network used to match a 50-ohm unbalanced output of a vacuum tube final amplifier?

Accepted Answer

A Pi-network with an additional series inductor on the output

Answer

Explanation:
A Pi-L-network is a Pi-network with an additional shunt inductor on the output, used for matching a vacuum tube final amplifier to a 50-ohm unbalanced output.

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Ham Radio Technician Test Practice Test

Free Ham Radio Technician Amateur Questions and Answers