Questions I Get Wrong on the Technician Exam - Part 1
Since I'm rounding out my last technician test on the podcast, I thought I'd focus in on the areas I get wrong on the exam.
VHF Frequency Limits
I think this question is really tricky and requires just memorizing the chart of frequency limits. A few things I learned from this question was that the frequencies are separated by a factor of 10 and is always referenced in MHz. That would have ruled out two answers. From there, I just need remember that VHF starts at 30MHz.
- 0.03 to 0.30 MHz is Very Low Frequency (VLF) used in Radio Nav and Maritime Radio. Not used in Ham Radio.
- 0.03 to 0.3 MHz is Low Frequency (LF) used in Long Wave Radio, Maritime Radio and Navigation.
- 0.3 MHz to 3 MHz is Medium Frequency (MF) used in AM Radio, HAM Radio and Navigation.
- 3MHz to 30 MHz is High Frequency (HF) used in CB, Point to Point Radio and Search and Rescue Services and Shortwave Radio.
- 30 MHz to 300 MHz is Very High Frequency (VHF) used in FM Radio and VHF Broadcast TV.
- 300 MHz to 3000 MHz Ultra High Frequency (UHF) used in UHF Broadcast TV, Cell Phones, Microwave Links, Wi-Fi in 2.4 Band, SatComms.
- 3000 MHz to 30000 MHz Super High Frequency (SHF) used in Microwave Links, Wi-Fi in the 5 GHz Band and SatComms
- 30000 MHz to 300000 MHz Extra High Frequency (EHF) used in Microwave Links.
The Ability to Store Energy in a Magnetic Field
This is a tricky question for me because an inductor and a capacitor store energy. The difference between an inductor and a capacitor is that the inductor stores energy in a magnetic field and a capacitor stores energy in an electric field.
- Inductance is the ability of an inductor to store energy and it does this in the magnetic field that is created by the flow of electrical current.
- An inductor, also called a coil, choke or reactor, is a passive two-terminal component that stores energy in a magnetic field when electric current flows through it, typically consisting of an insulated wire wound into a coil around a core.
- Capacitance is the ability of a system to store an electric charge.
- A capacitor is a passive two terminal electrical component used to store energy electrostatically in an electric field.
- This was explained to me by a podcast listener as being like a brick oven that stores heat.
- Admittance is a measure of how easily a circuit or device will allow current to flow. It is a reciprocal of impedance.
- Impedance is the effective resistance of an electric circuit or component to alternating current from the combination of resistance and reactance.
- Resistance is the measure of opposition to current flow in an electrical circuit.
The Approximate Bandwidth of a VHF Repeater FM Phone Signal
This was a question that confused me because I was conflating two different things. Bandwidth is referring to the size of the transmission, not the band space. FM uses 10 to 15KHz to transmit, with the 10 to 15 KHz being the amount of space the transmission takes on the bandwidth. Josh pulled out a radio in FM mode to show me that the radio regulates FM transmissions to not exceed 10 to 15KHz and that's when I finally got it.
That was a round about explanation to basically say I need to associate 10 to 15 KHz to FM.
Thanks for joining me while I bare my lack of knowledge. Come back whenever the next time I decide to post about questions I get wrong on the Technician exam.
Please note: Josh did not review this post so if I have these details wrong, you know why my “technical advisor” is necessary.