Free Ham Radio Technician Amateur Questions and Answers — Questions and Answers

Question 1: How does a fast-scan (NTSC) television system produce an interlaced scanning pattern?

By scanning odd numbered lines in one field and even numbered lines in the next (Correct answer)
By scanning two fields simultaneously
By scanning each field from bottom to top
By scanning lines from left to right in one field and right to left in the next

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

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?

Less than 180 degrees
More than 180 degrees but less than 360 degrees (Correct answer)
Exactly 180 degrees
The entire cycle

Correct answer: More than 180 degrees but less than 360 degrees

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?

There is more power going into the antenna (Correct answer)
There is possibly a short to ground in the feed line
The transmitter is not properly neutralized
There is an impedance mismatch between the antenna and feed line

Correct answer: There is more power going into the antenna

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?

Change carrier depletion
Excessive inverse voltage
Excessive junction temperature (Correct answer)
Insufficient forward voltage

Correct answer: Excessive junction temperature

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?

A matching network in which all components are isolated from ground
A Phase Inverter Load network
A Pi-network with an additional series inductor on the output (Correct answer)
A network with only three discrete parts

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

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.

Question 6: What may make a series RLC circuit's reactance voltage exceed the voltage applied to the circuit as a whole?

Capacitance
Resonance (Correct answer)
Resistance
Conductance

Correct answer: Resonance

Explanation: In a series RLC circuit, the voltage across the reactances can be higher than the voltage applied to the entire circuit when the circuit is operating at resonance. At resonance, the inductive reactance and capacitive reactance cancel each other out, and the impedance of the circuit is at its minimum. This causes the voltage across the series combination of the inductor and capacitor to be higher than the applied voltage, leading to a phenomenon called voltage magnification.

Question 7: When a transmission line is shorted at the other end, what impedance does it present to a generator?

Very low impedance (Correct answer)
Very high impedance
The same as the output impedance of the generator
The same as the characteristic impedance of the line

Correct answer: Very low impedance

Explanation: When a 1/2-wavelength transmission line is shorted at the far end, it presents a very high impedance at the input end, also known as the input impedance.

Question 8: What situations give digital messaging an exception to the Part 97 third-party regulations that apply to traditional forms of communication?

Under no circumstances (Correct answer)
When under automatic control
When messages are encrypted
When messages are not encrypted

Correct answer: Under no circumstances

Part 97 of the FCC regulations, also known as the Amateur Radio Service rules, governs the operations of amateur radio operators in the United States. These regulations define the privileges and responsibilities of amateur radio operators, including the handling of third-party communications.

Question 9: According to FCC regulations, what is the maximum bandwidth allowed for amateur radio stations using USB frequencies in the 60-meter band?

1.8 kHz
2.8 kHz (Correct answer)
5.6 kHz
3 kHz

Correct answer: 2.8 kHz

FCC rules limit amateur transmissions on the 60-meter band to a maximum bandwidth of 2.8 kHz, which accommodates a standard USB voice signal while keeping channels narrow on this shared band. The other values are either too narrow to pass a normal voice signal (1.8 kHz, smaller) or exceed the allowed limit (5.6 kHz).

Question 10: How long would a 1/4 wave vertical antenna cut for 28.5 MHz be roughly speaking?

21 feet
16 feet
8 feet (Correct answer)
11 feet

Correct answer: 8 feet

Using the standard length formula for a quarter-wave vertical, L (feet) ≈ 234 ÷ frequency in MHz, so 234 ÷ 28.5 ≈ 8.2 feet, which rounds to about 8 feet. The larger figures (11, 16, 21 feet) correspond to lower frequencies or longer fractions of a wavelength, not a quarter wave at 28.5 MHz.

Question 11: Why is it necessary to ground every piece of station equipment with a metal enclosure?

It prevents to blown fuse in the event of an internal short circuit
It prevents signal overload
It ensures that hazardous voltages cannot appear on the chassis (Correct answer)
It ensures that the neutral wire is grounded

Correct answer: It ensures that hazardous voltages cannot appear on the chassis

Grounding every piece of station equipment with a metal enclosure is necessary to ensure safety and prevent hazardous voltages from appearing on the chassis or outer casing of the equipment. This practice is an essential safety measure for both the equipment and the individuals operating or coming into contact with the station.

Question 12: Before sending out a CW or phone CQ, what is a feasible approach to prevent unwanted interference on an ostensibly clear frequency?

Listen for 2 minutes before calling CQ
Send "QSY" on CW or if using phone, announce "the frequency is in use," then give your call sign and listen for a response
Send the letter "V" in Morse code several times and listen for a response, or say "test" several times and listen for a response
Send "QRL?" on CW, followed by your call sign; or, if using phone, ask if the frequency is in use, followed by your call sign (Correct answer)

Correct answer: Send "QRL?" on CW, followed by your call sign; or, if using phone, ask if the frequency is in use, followed by your call sign

To avoid interfering with someone already using a seemingly clear frequency, you ask whether it's in use first: send 'QRL?' on CW or ask 'Is the frequency in use?' on phone, followed by your call sign, then listen. Simply listening for two minutes is unreliable, sending 'QSY' or announcing the frequency is in use is incorrect procedure, and sending 'V' or saying 'test' transmits without first asking and can cause the very interference you're trying to prevent.

Question 13: How soon do charged particles from coronal mass ejections start to interfere with radio waves on Earth?

20 to 40 hours (Correct answer)
14 days
28 days
4 to 8 minutes

Correct answer: 20 to 40 hours

Charged particles from coronal mass ejections (CMEs) can start to interfere with radio waves on Earth relatively quickly, typically within 20 to 40 hours after the ejection occurs. A coronal mass ejection is a significant release of plasma and magnetic fields from the solar corona, the outermost layer of the Sun's atmosphere. When a CME is directed towards Earth, it can cause disturbances in the Earth's magnetosphere and ionosphere due to the interaction between the CME's charged particles and the Earth's magnetic field.

Question 14: What is the longest possible distance that can be typically reached in one hop using the F2 region?

1,200 miles
2,500 miles (Correct answer)
180 miles
12,000 miles

Correct answer: 2,500 miles

The longest possible distance that can typically be reached in one hop using the F2 region of the ionosphere is significantly greater than 2,500 miles. In amateur radio and long-distance communications, it is not uncommon to achieve communication distances exceeding 5,000 miles (approximately 8,047 kilometers) and even up to 10,000 miles (approximately 16,093 kilometers) in a single hop using the F2 ionospheric layer. Under favorable ionospheric conditions and during periods of high solar activity, the F2 region can support long-distance skywave propagation, allowing radio signals to travel vast distances before being refracted back to Earth.

Question 15: Which of the following describes a log periodic antenna's benefits?

Harmonic suppression
Wide bandwidth (Correct answer)
Polarization diversity
Higher gain per element than a Yagi antenna

Correct answer: Wide bandwidth

The log periodic antenna's primary benefit is its wide bandwidth. A log periodic antenna is a type of directional antenna that is designed to operate over a broad range of frequencies. Unlike other types of antennas that are resonant at a specific frequency or a narrow range of frequencies, the log periodic antenna exhibits relatively consistent performance over a wide frequency range. This wide bandwidth allows the log periodic antenna to cover multiple frequencies without the need for constant retuning or adjustments.

Question 16: What qualifies as a defining feature of the FT8 mode of the WSJT-X family?

Each transmission takes exactly 60 seconds
Typical exchange are limited to call signs, grid locators, and signal reports (Correct answer)
It is a keyboard-to-keyboard chat mode
It is limited to use on VHF

Correct answer: Typical exchange are limited to call signs, grid locators, and signal reports

A defining feature of the FT8 mode of the WSJT-X family is that typical exchanges are limited to call signs, grid locators, and signal reports. FT8 is a digital mode developed for weak-signal communication, especially under challenging propagation conditions on HF (High Frequency) and VHF (Very High Frequency) amateur radio bands. It is a popular mode for amateur radio operators engaged in worldwide communication and making contacts under weak signal conditions.

Free Ham Radio Technician Amateur Questions and Answers

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