FREE Ham Radio Technician II Questions And Answers
How is a complicated impedance converted to a resistive impedance by an impedance-matching circuit?
By eliminating the reactive component of the impedance and adjusting the resistive component to a desired value, an impedance-matching circuit converts a complex impedance to a resistive impedance. Remember that capacitors and inductors are responsible for the "reactive" portion of the impedance, and impedance matching will enable us to convert the signal to entirely resistive. Ironically, to remove the reactive component of the impedance, you must employ inductors or capacitors.
An isotropic antenna is what?
As a benchmark for antenna gain, an isotropic antenna is a hypothetical, omnidirectional antenna. The isotropic antenna radiates uniformly in ALL directions in theory. In contrast to our hypothetical isotropic antenna, real antennas produce radiation patterns and gain in different directions.
When the line is open at the other end, what impedance does a 1/4-wavelength transmission line present to a generator?
You'll occasionally need to know why a feedline isn't working the way you expect it to. When the line is open at the far end, a 1/4-wavelength transmission line has an extremely low impedance to a generator.
Which of the following carrier frequencies is prohibited for LSB AFSK transmissions on the RTTY 17-meter band and the 18.068–18.110 MHz data segment?
The sideband will extend BELOW 18.068 if you transmit on the 18.068 lower side band because it is lower, hence your signal will be out of the permissible range if you do so.
As both 18.100 MHz and 18.107 MHz are inside the side, they are both fine. Even though 18.110 MHz is on the edge of the band, it is acceptable since for lower side band the transmitted signal would fall below 18.110 MHz and yet be within the band.
What is the phase connection between a series resonant circuit's resonance voltage and current?
When the voltage across a series resonant circuit and the circuit's current are both at resonance, the voltage and current are in phase. Remember that the frequency at which the capacitive reactance equals the inductive reactance is the resonance in an LC or RLC circuit.
What mathematical formula should be used to determine the power lost by a series linear voltage regulator?
The voltage regulator aids in ensuring that the voltage in your circuit remains constant. The voltage difference from input to output multiplied by output current is the equation for estimating the power dissipated by a series linear voltage regulator.
Which of the following best depicts how a receiving filter might block signals coming from an adjacent channel?
Filters are an excellent tool for bringing in faint signals or obtaining only the signal you are interested in hearing at the time. Filters assist the radio focus on the signal in a specific section of the spectrum or eliminate erroneous signals that may be produced by mixing. The capability of a receiving filter to block signals coming from an adjacent channel is referred to as form factor.
How can the noise produced by a car alternator be reduced in both conducted and radiated forms?
Direct connection to the battery reduced the impact of the alternator on the power signal, while coaxial capacitors assisted in removing the AC noise from the radio's DC power circuit.
What is the normalization procedure in relation to a Smith chart?
A Smith Chart is frequently used to establish the length and location of an impedance matching stub. The Smith chart assists in reassigning impedance values in relation to the prime center through a procedure known as normalization. Here, the crucial concept is impedance.
To employ a hairpin matching system, how must the driving element of an antenna be tuned?
Because mismatches result in signal loss, you want to match your antenna's and feedline's impedance to that of your transceiver as nearly as you can for best performance. A hairpin match is a U-shaped piece of cable that is widely used in the well-known tape measure yagi antenna used to operate satellites. It is used to match driven parts of a yagi antenna. Imagine a hairpin as an inductor or a coil. Because capacitance and inductance cancel each other out, an antenna's driving element must be calibrated in order to use a hairpin matching system, which requires capacitive reactance.
In a fast-scan (NTSC) television system, how frequently are new frames transmitted?
30 frames per second is the standard frame rate for US television signals.
What occurs as the length of a long, unterminated wire antenna increases in terms of its radiation pattern?
The radiation pattern is influenced by the wire length; as the length of an unterminated long wire antenna increases, the lobes line more with the wire's direction. An excellent receiving antenna is a long wire, especially on low bands like 160 and 80 meters.
When during the day does transequatorial propagation work best?
Transequatorial transmission is most effective in the afternoon or early evening, so if you want to make a South American correct, you might want to get up early or wait till then.
Which of the following geopolitical definitions best fits "Line A"?
Amateur stations are not permitted to transmit in the 420-430 MHz range in the contiguous 48 states or north of Line A. This is to safeguard other users and the public safety in Canada.
What is the main benefit of an inductor with a toroidal core rather than a solenoidal core?
While solenoidal inductors have a bar shape, toroidal inductors have a ring shape. The shape of a toroidal core inductor confines the majority of the magnetic field within the core material, which is its main benefit.
Where are the rectangular coordinates for the impedance of a pure resistance plotted?
The phase angle of a circuit incorporating resistance, inductive, and/or capacitive reactance is frequently displayed using polar coordinates. To graph the impedance of a circuit, the X axis represents the resistive component and the Y axis represents the reactive component. The impedance of a pure resistance is displayed on rectangular coordinates.