What is the difference between direct FSK and audio FSK?
AnswerDirect FSK modulates the transmitter VFO
Direct FSK changes the transmitter's VFO or carrier frequency directly, while audio FSK sends tones through an SSB transmitter.
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Which of the following is a characteristic of using a gamma match with a Yagi antenna?
AnswerIt does not require the driven element to be insulated from the boom
A gamma match can match a Yagi while leaving the driven element electrically connected to the boom, so the element does not have to be insulated from it.
What frequency range is referred to as HF?
Answer3 to 30 MHz
HF means High Frequency and spans 3 MHz through 30 MHz.
What is the name given to an impurity atom that adds holes to a semiconductor crystal structure?
AnswerAcceptor impurity
An impurity that creates holes in a semiconductor crystal is called an acceptor impurity.
What does LUF stand for?
AnswerThe Lowest Usable Frequency for communications between two specific points
LUF means Lowest Usable Frequency for communication between two specific points.
How is squelch adjusted so that a weak FM signal can be heard?
AnswerSet the squelch threshold so that receiver output audio is on all the time
Squelch mutes receiver audio below a signal threshold. To hear a very weak FM signal, lower the threshold until the receiver audio remains open instead of being muted.
Which of the following limits the highest frequency signal that can be accurately displayed on a digital oscilloscope?
AnswerSampling rate of the analog-to-digital converter
The analog-to-digital converter must sample fast enough to represent the waveform accurately. Its sampling rate therefore limits the highest frequency a digital oscilloscope can display correctly.
Which element of a vacuum tube regulates the flow of electrons between cathode and plate?
AnswerControl grid
In a vacuum tube, the control grid varies the electron flow from cathode to plate and therefore controls tube current.
What is the frequency response of the circuit in E7-3 if a capacitor is added across the feedback resistor?
AnswerLow-pass filter
At higher frequencies the capacitor lowers the feedback impedance, reducing closed-loop gain and creating a low-pass response.
Who may select a desired call sign under the vanity call sign rules?
AnswerAny licensed amateur
Any licensed amateur may select a desired call sign under the vanity call sign rules.
How is an interlaced scanning pattern generated in a fast-scan (NTSC) television system?
AnswerBy scanning odd-numbered lines in one field and even-numbered lines in the next
Interlaced NTSC scanning divides a frame into two fields: one scans the odd-numbered lines and the other scans the even-numbered lines.
What is the output PEP of 500 volts peak-to-peak across a 50-ohm load?
Answer625 watts
A 500-volt peak-to-peak sine wave has 250 volts peak and about 176.8 volts RMS. Squaring that and dividing by 50 ohms gives 625 watts.
Which of the following is a customary way to indicate a station is listening on a repeater and looking for a contact?
AnswerThe station’s call sign followed by the word “listening”
On a repeater, a brief call sign followed by “listening” tells others that you are available for a contact without making a full CQ call.
What is the most common configuration of an optoisolator or optocoupler?
AnswerAn LED and a phototransistor
The most common optoisolator pairs an LED with a phototransistor, transferring a signal optically while maintaining electrical isolation.
What is the approximate length of the driven element of a Yagi antenna?
Answer1/2 wavelength
The driven element of a conventional Yagi is approximately one-half wavelength long.
How are the capacitors and inductors of a low-pass filter Pi-network arranged between the network’s input and output?
AnswerA capacitor is connected between the input and ground, another capacitor is connected between the output and ground, and an inductor is connected between the input and output
A low-pass Pi network uses a capacitor from input to ground, a series inductor, and another capacitor from output to ground.
What is component 4 in figure T-2?
AnswerTransformer
Component 4 in figure T-2 is a transformer, represented by magnetically coupled windings.
Why is it not legal to transmit a 3 kHz bandwidth USB signal with a carrier frequency of 14.348 MHz?
AnswerThe upper 1 kHz of the signal is outside the 20-meter band
A 3 kHz-wide USB signal extends upward from the displayed carrier frequency. With the carrier at 14.348 MHz, the upper portion of the emission extends beyond the 14.350 MHz band edge.
How do you join a contact between two stations using the PACTOR protocol?
AnswerJoining an existing contact is not possible, PACTOR connections are limited to two stations
A PACTOR connection is a point-to-point session between two stations, so a third station cannot simply join an existing connection.
Why do most solid-state transmitters reduce output power as SWR increases beyond a certain level?
AnswerTo protect the RF output amplifier transistors
High SWR can produce large reflected-power stresses at the transmitter output. Solid-state radios often reduce power automatically to protect their RF output transistors.
When evaluating RF exposure levels from your station at a neighbor’s home, what must you do?
AnswerEnsure signals from your station are less than the uncontrolled maximum permissible exposure (MPE) limits
A neighbor is part of the general public, so exposure at the neighbor's home must remain below the uncontrolled maximum permissible exposure limits.
What is the function of a power supply bleeder resistor?
AnswerIt discharges the filter capacitors when power is removed
A bleeder resistor provides a discharge path for power-supply filter capacitors after power is removed, reducing the time that dangerous stored voltage remains.
What is the result of increasing the Q of an impedance-matching circuit?
AnswerMatching bandwidth is decreased
Increasing Q makes an impedance-matching network more selective, so the range of frequencies over which it provides a good match becomes narrower.
When may amateur stations transmit information in support of broadcasting, program production, or news gathering, assuming no other means is available?
AnswerWhen such communications are directly related to the immediate safety of human life or protection of property
Amateur stations may support broadcasting, program production, or news gathering only when the communication directly concerns the immediate safety of human life or protection of property and no other means is available.