Hello everybody and welcome back to Everything Hamradio! Today we are going to continue our series on the Technician Class License Question Pool! Today we will be talking about Multi-Mode Radios.
As always, the correct answers will be in bold. I also recommend that you only read the correct answers when studying for your test. If you do this, when you take your test and you see a question, there will be a better chance that the correct answer will jump out at you easier. Some say that this approach is kind of like cheating, but the way that I see it, you will always be learning something in this hobby and you don’t have to know everything there is to know about the hobby to get your license.
If you would like to purchase a copy of the Technician Class study book, written by Gordon West, WB6NOA with Eric P. Nichols, KL7AJ, that this series is loosely based around, below is a link to it.
Let’s move on to the good stuff, shall we?
T7A02 What is a transceiver?
- A type of antenna switch
- A unit combining the functions of a transmitter and a receiver
- A component in a repeater which filters out unwanted interference
- A type of antenna matching network
A transceiver is a unit that has both a receiver and a transmitter built into one unit. About 30ish years ago, you had to have a separate receiver and transmitter. I’m sure it made for a cluttered desk and/or ham station because not only did you have to have a separate receiver and transmitter but they were big and clunky.
T7A09 Which of the following devices is most useful for VHF weak-signal communication?
- A quarter-wave vertical antenna
- A multi-mode VHF transceiver
- An omni-directional antenna
- A mobile VHF FM transceiver
Weak signal communications is done on VHF Single Side Band(SSB), there for you can’t use a FM transceiver to work it. A Vertical t antenna, also known as an omni directional antenna, will work but a directional antenna works better when working weak-signal communications.
T8A03 Which type of voice mode is most often used for long-distance (weak signal) contacts on the VHF and UHF bands?
Rather than using FM on 2 meter like you would on a repeater or simplex, using Single Side Band(SSB) will allow you to work those long-distance(weak signal) contacts.
T8A07 What is the primary advantage of single sideband over FM for voice transmissions?
- SSB signals are easier to tune
- SSB signals are less susceptible to interference
- SSB signals have narrower bandwidth
- All of these choices are correct
With SSB, you will only use half as much bandwidth as you would when you use the FM mode. This allows for more communications in a smaller spectrum area. Since the weak signal portions of the 6M, 2M, 1 1/4M, and a 432 MHz and 1296 MHz, using as little bandwidth as possible is important.
T8A01 Which of the following is a form of amplitude modulation?
- Packet radio
- Single sideband
- Phase shift keying
Single-Side Band is a type of amplitude modulation. Your voice, when you talk, will increase and decrease the amplitude of your signal. When the amplitude of your transmission increases so does your power output to a certain degree.
T8A06 Which sideband is normally used for 10 meter HF, VHF and UHF single-sideband communications?
- Upper sideband
- Lower sideband
- Suppressed sideband
- Inverted sideband
You will use Upper Sideband on all amateur bands except for 40 meters and above.
T7A08 Which of the following describes combining speech with an RF carrier signal?-
- Impedance matching
- Low-pass filtering
Modulation is the process of combining information, such as your voice, and a radio carrier.
T8A08 What is the approximate bandwidth of a single sideband voice signal?
- 1 kHz
- 3 kHz
- 6 kHz
- 15 kHz
The full bandwidth of a voice signal is approximately 5-6 kHz, and since single sideband uses only half of the full bandwidth, the answer is 3 kHz
T4B09 Which of the following is an appropriate receive filter bandwidth to select in order to minimize noise and interference for SSB reception?
- 500 Hz
- 1000 Hz
- 2400 Hz
- 5000 Hz
Since the approximate modulation of voice on single sideband is 2500-3000 Hz, the best choice of the provided answers is 2400 Hz.
T2B13 Which of the following is true of the use of SSB phone in amateur bands above 50 MHz?
- It is permitted only by holders of a General Class or higher license
- It is permitted only on repeaters
- It is permitted in at least some portion of all the amateur bands above 50 MHz
- It is permitted only on when power is limited to no more than 100 watts
All bands above 50 MHz has at least a small section designated for weak signal communication, normally in the lower portions of the band.
T4B06 Which of the following controls could be used if the voice pitch of a single-sideband signal seems too high or low?
- The AGC or limiter
- The bandwidth selection
- The tone squelch
- The receiver RIT or clarifier
The receiver RIT or clarifier can be used for fine tuning when the voice or CW you are hearing seems too high or low. Always set it to neutral to begin with then turn the knob one way or the other to fine tune the signal for best reception.
T4B07 What does the term “RIT” mean?
- Receiver Input Tone
- Receiver Incremental Tuning
- Rectifier Inverter Test
- Remote Input Transmitter
RIT stands for Receiver Incremental Tuning. It us usually only found on higher end transceivers mobile or base station equipment. It is used to adjust the receive frequency, normally only up to 1kHz, without changing the transmit frequency. This is especially useful when you are working satellite to compensate for the Doppler shift. When you are not working satellite, it is best to keep the knob centered or disabled so that you are receiving and transmitting on the same frequency.
T4A01 Which of the following is true concerning the microphone connectors on amateur transceivers?
- All transceivers use the same microphone connector type
- Some connectors include push-to-talk and voltages for powering the microphone
- All transceivers using the same connector type are wired identically
- Un-keyed connectors allow any microphone to be connected
Many different brands of radios have what appear to be the same microphone connect, unfortunately that is not always true. A small amount of power is normally sent on one pin from the radio to the microphone to power the microphone. Even though the microphone plug on different radios may appear the same, the power may be on a different pin on different brands. If you plug in a Icom microphone into a Yaseu radio, you could inadvertently fry your radio which could lead to a costly repair. You should always make sure that you use the same brand microphone as your radio, or the correct adapter so you don’t damage your radio.
T7A05 What is the name of a circuit that generates a signal of a desired frequency?
- Reactance modulator
- Product detector
- Low-pass filter
A oscillator is a circuit that is designed to create the base frequency of your transmission. It is generally either a quartz crystal or “multivibrator” circuit in digital radios.
T8A05 Which of the following types of emission has the narrowest bandwidth?
- FM voice
- SSB voice
- Slow-scan TV
Out of all these choices, CW uses the smallest amount of bandwidth. FM and Slow-scan TV uses the most amount of these choices, followed by SSB which uses half as much.
T8A11 What is the approximate maximum bandwidth required to transmit a CW signal?
- 2.4 kHz
- 150 Hz
- 1000 Hz
- 15 kHz
While FM uses approximately 5MHz, SSB uses half that at 2,500 kHz, CW uses the least amount of pretty much any other mode in amateur radio using on 150 Hz!
T4B10 Which of the following is an appropriate receive filter bandwidth to select in order to minimize noise and interference for CW reception?
- 500 Hz
- 1000 Hz
- 2400 Hz
- 5000 Hz
While using CW, you can select the smallest filter you have on your radio, at 500 Hz.
T4B08 What is the advantage of having multiple receive bandwidth choices on a multimode transceiver?
- Permits monitoring several modes at once
- Permits noise or interference reduction by selecting a bandwidth matching the mode
- Increases the number of frequencies that can be stored in memory
- Increases the amount of offset between receive and transmit frequencies
When using different modes, it is always best to use the smallest amount of filter to match the type of communications you are using. If you are using CW and you have a filter set for the width of SSB, you could be missing people calling CQ. If you are using SSB, and you have your filter set for CW, you might be hearing a lot more noise than you need to.
T7A01 Which term describes the ability of a receiver to detect the presence of a signal?
- Total Harmonic Distortion
The better your sensitivity is on your radio, the more likely you are hear a weak-signal. The weaker the signal, the harder it is for your radio to detect it.
T7A03 Which of the following is used to convert a radio signal from one frequency to another?
- Phase splitter
A mixer takes the base frequency that your oscillator is putting out and combines it with your voice and sends it out over the air.
T7A04 Which term describes the ability of a receiver to discriminate between multiple signals?
- Discrimination ratio
- Harmonic Distortion
The selectivity of your radio is where your radio will receive and send out on your speakers only the frequency that you want to hear.
T4B12 What is the function of automatic gain control or AGC?
- To keep received audio relatively constant
- To protect an antenna from lightning
- To eliminate RF on the station cabling
- An asymmetric goniometer control used for antenna matching
The AGC is the function that keeps your audio at a relatively constant level. If you yell into the microphone, it’s is not going to help much, but if you are talking and you move away or closer to the microphone, or raise your voice, the AGC will attempt to level it out.
T7A11 Where is an RF preamplifier installed?
- Between the antenna and receiver
- At the output of the transmitter’s power amplifier
- Between a transmitter and antenna tuner
- At the receiver’s audio output
The RF preamplifier is installed between the antenna and receiver. It is used to amplify the incoming signal so the receiver can hear it better.
T7A06 What device takes the output of a low-powered 28 MHz SSB exciter and produces a 222 MHz output signal?
- High-pass filter
- Low-pass filter
- Phase converter
A Transverter is a device that you can use to convert an old CB radio into a 222MHz radio. So if you have some of those older CB radios that had a sideband switch or extra filters, don’t throw them away just yet.
T4A03 Which is a good reason to use a regulated power supply for communications equipment?
- It prevents voltage fluctuations from reaching sensitive circuits
- A regulated power supply has FCC approval
- A fuse or circuit breaker regulates the power
- Power consumption is independent of load
By using a regulated power supply, it will prevent voltage fluctuations from reaching your radio and potentially damaging it.
So that brings us to the end of this section. Next week we will be talking about Run Some Interference Protection! Please share my blog with your friends and if you have not done so already, please subscribe to my email list to get the latest and quickest notifications of any new post that I publish. . If you would rather, you can also sign up for my RSS feed. Please Like me on Facebook, and follow me on Twitter, Google+, LinkedIn and StumbledUpon. Links to all of these can be found under social on the menu.
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Until next time…
73 de Curtis, K5CLM