FREE Ham Radio Extra Class Questions and Answers
What benefit does an oscilloscope have over a digital voltmeter, specifically?
A digital voltmeter can just provide numbers without any indication of time. With a digital voltmeter, even simple waveforms like searching for a peak can be challenging. This is why, in some circumstances, tuning for a peak in a circuit is best done with an analog voltmeter with a needle. An oscilloscope has the benefit of being able to measure complicated waveforms in comparison to a digital voltmeter.
Which ionospheric layer is the nearest to Earth's surface?
D, E, and F are the ionosphere's three levels. The F layer will split into the F1 and F2 layers when there are higher ionization levels. The ionospheric layer that is closest to the Earth's surface is the D layer.
If an oscilloscope records 200 volts peak-to-peak across a 50 ohm dummy load attached to the transmitter output, what is the output PEP from the transmitter?
If an oscilloscope detects 200 volts peak-to-peak across a 50-ohm dummy load connected to the transmitter output, 100 watts are the output PEP from the transmitter. They need the power measured in watts for the calculations, and we are provided 200 volts peak-to-peak across a 50-ohm load. A quick reminder: Watts equal Volts times Amperes. Let's first determine the current. However, the voltage was supplied peak to peak. When using the formula Amperes * Volts = Watts, RMS (root mean square) voltage rather than peak-to-peak voltage is anticipated. Our power formula will be Watts = Voltage 2 / Resistance as we are only given ohms and volts. Get the peak voltage now. 200 Peak-to-Peak Volts / 2 = 100 Volts Peak because Peak Voltage = Voltage / 2. We now convert our volts peak to volts RMS. Volts RMS = Volts Peak / SqRt(2), hence. In light of the fact that 100 Volts Peak / SqRt(2) = 70.7106 Volts RMS, our formula now reads Watts = (100 / SqRt(2)) 2 / 50. Therefore, 5000/50 = 100 Watts. Using basic math, you must first translate the peak-to-peak voltage into a peak voltage: Peak Voltage = Peak-to-Peak Voltage / 2. We now need to convert our peak voltage to RMS voltage. Voltage RMS equals Peak Voltage / SqRt(2) in simple math. With the voltage in RMS at your disposal, you may perform the standard calculation of Watts as Voltage = Voltage 2 / Resistance.
What benefit does employing a ferrite core toroidal inductor provide?
Compared to a few years ago, toroidal inductors are now readily accessible and reasonably priced. They possess many of useful qualities for amateur radio applications. They can be used to match various impedances, such as in an end-fed half-wave antenna. In many interface cables, they are also employed as a choke design to stop the flow of undesired RF. Therefore, all of the benefits of employing a ferrite core toroidal inductor include the ability to get high values of inductance, the ability to tailor the core's magnetic characteristics for a particular frequency range, and the fact that the majority of the magnetic field is confined within the core.
In a 146.52 MHz FM phone transmitter with a 5 kHz dispersion, what is the frequency deviation for a 12.21 MHz reactance modulated oscillator?
We have a 12.21 MHz reactance modulated oscillator with a 5-kHz variation, and we need to compute the frequency deviation. The transmitter will operate at 146.52 MHz. Two steps will be needed to complete this calculation. We must first determine the FM transmitter's multiplication factor. Transmitter frequency divided by oscillator frequency is the multiplication factor. 146.52 MHz divided by 12.21 MHz equals a factor of 12. We can now answer the remaining problem since we know our multiplication factor. Transmitter Deviation in Hz / Multiplication Factor is the formula for frequency deviation. 5000 Hz / 12 = 416.66 Hz as a result. The frequency deviation for a 12.21-MHz reactance-modulated oscillator in a 5-kHz deviation, 146.52 MHz FM phone transmitter is 416.7 Hz, among the options.
How do the gains for the same antenna expressed in dBi and dBd compare?
Use dBi numbers when comparing an antenna's gain to that of an isotropic antenna; use dBd units when comparing your antenna's gain to that of a common reference dipole. You can use antenna modeling tools to see that the difference between dBi and dBd gains for the identical antenna is 2.15 dB. An isotropic antenna is omnidirectional; it radiates the same quantity in all directions, therefore this mismatch is easily explained. A dipole's radiation pattern is a little different because it reveals that the main lobes are located along the antenna's elements.
What is a 22,000 picofarad (pF) capacitor's value in nanofarads (nF)?
A picofarad is equal to 1 x 10-12 and a nanofarad to 1 x 10-9. As a result, 1 nanofarad equals 1,000 picofarads. So, 22 nanofarads are required to equal a 22,000-picofarad capacitor.