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Microphones convert audio into electrical signals. There are a few types, such as dynamic, which is a speaker working in reverse; and the electret condenser microphone, which often include a tiny pre-amplifier, requiring a few volts at low current to power it.
It is important to note that while microphones may use the same connector, they may be also wired differently. Typically, the push-to-talk operates by the key or button connecting the PPT line to ground. Some connectors include a voltage for powering amplifiers in the microphone, etc. Some with number pads include DTMF chips, others communicate with the radio's processor. Some radios also have a low level received audio output, used when operating digital modes. Others have UP, DOWN, and FAST buttons, to allow tuning from the mike.
The desk-top radios from the Japanese makers use an 8 pin version of the screw-locked round microphone connector used in better CBs, but each uses a different wiring scheme. These have pins on the panel-mounted connector, and socket holes on the "plug". Mobile radios often use an 8 pin RJ-45 one, as used in PC networking.
Hand-helds use a range of connectors, one being the 3.5mm and 2.5mm pair, the larger for headphones or a speaker, the smaller for the microphone. These can be used for speaker-microphones, which can be clipped to an epaulette or jacket, or to a headset with a boom microphone. While there are moulded combination plugs, older Bakelite or hard plastic cased plugs will fit, allowing packet modems to be connected. Some use 4 contact 3.5 mm plugs, with a waterproofing screw-down cover, the Yaesu VX-7R* being an example. Adaptors are also available to allow 2-pin microphones and modems / TNCs to be connected. The microphone connector has a voltage on it, both to power the electret microphone, and to sense when this is drawing current, when the microphone is put into circuit by the PTT switch. To key them with a TNC a resister to ground is switching into this line, while audio is fed via a capacitor, which provides DC isolation.
* Note that the similar looking Vertex-Standard VXA-700 Spirit comes with an adapter for aviation headsets, 6.5 mm (0.25") headphones, and 5.3mm (0.206 "). With standard settings these send the microphone audio to the headphones, so won't work with the handheld speaker-mikes use with the '7R.
For home or mobile radios, RF from the antenna system can sometimes get back into the microphone cable, causing distortion, or other radio misbehaviour. Clipping on a ferrite sleeve may help.
Some radios have microphone gain controls, and if this is set too high for the connected microphone, the signal may become distorted. The same applies with sending packet, RTTY, or other digital modes.
I have used an old green Pye carbon microphone, as seen in "Party under Parliament House", with a HT, but have no idea how it sounded, other than that I was able to make a contact. Carbon microphones are used in old telephones.
The most basic way to send Morse is via a "straight key", as probably seen on movies re the Titanic, using downward pressure to operate the key.
Various keyers use a sideways motion, apparently more ergonomic, with one direction generating dits, the other dahs. Mechanical versions include the famous Vibroplex, while there are electronic keyers which use simple contacts, and generate the Morse elements via an electronic circuit. This function is now built into many radios, such that only the contacts are needed.
The power connection to the radio must be made using heavy copper cable. The length should be kept reasonably short. Both factors reduce voltage drop.Where possible a new cable should be run from the battery, with the positive connected to the stud on the positive battery terminal clamp. The negative connection point should be either the battery negative, or the body at or near the battery strap. The exam also says the engine grounding strap, which may not actually be ideal.
Typically you might crimp one end of the wire from a pre-wired heavy duty fuse holder to an appropriately sized ring terminal, which attaches to the battery, and the other end via a butt connector to fine stranded 6 mm² wire (about 10 AWG), which goes into the vehicle cab via a spare gasket in the firewall. The negative wire is crimped to an eye terminal too. The wires should be kept away from high temperature areas. If you only have a single colour of wire, colour code it using electrical tape or heatshrink. Crimped terminals have yellow, blue, and red colour-coded sleeves, which indicates the wire size, from largest to thinnest, and yellow being suitable for the 6 mm² wire. These are available from automotive shops, but the pressed metal crimpers do not generate sufficient pressure to get a good crimp.
This cable must be fused. A topic of debate is the connection of the negative or return line. This should not be fused, or if it is, use a value higher than the positive line. Note that there may be a secondary ground for the radio, such as via mounting screws or the antenna mount, which becomes the main ground if a fuse in the negative line opens. This is NOT GOOD!
Removed from the exam, a variable frequency whine may appear on either the received audio in your radio, or on your transmitted audio. This is from the alternator (the generator which charges the battery and powers the car's electrical systems). I expect this may be worse on transmit when more current is drawn from the alternator. A filter consisting of an inductor and capacitors can help filter this out.
The whine on transmitted audio is jokingly called a "remote tachometer", as your friends can hear your engine speed vary as you accelerate and change gears.
Regulated supplies maintain a near constant voltage output from low or zero current to the rated current, and thus prevent voltage fluctuations potentially affecting the electronics of the radio. The output of unregulated supplies can float to a high level when the radio is drawing little current due to being in receive mode and squelched. High mains voltages can translate to a higher than usual voltage on the secondary of the transformer, and thus on the output of an unregulated supply, or increase the heat dissipated by a "linear" regulated supply.
Note that "rigs" or radios are far less than 100% efficient. The FT-857D is advertised as 100 watts output up to 29.7 MHz, but the manufacturer recommends a 22 amp supply. While current draw may be significantly lower than this in the low bands using SSB, it really kicks up on AM at 29 MHz, as the finals become less efficient. 13.8 x 22 = 303.6 watts. When buying a supply, take into account that you may want to add a range of "12 volt" or "13.8 volt" powered accessories, and perhaps extra radios for special bands or modes.
The cable from the supply to the radio should be as short and as "chunky" possible. The lowest American Wire Gauge (AWG) or highest number of square millimetres has the lowest resistance. Replacement cables, and parts to make them, can be obtained from Powerwerx. Given fitting the heavier cables into "Powerpoles" is fiddly, pre-made ones may be easier.
Mobile style radios (and some HTs) can be powered from a 12 volt or similar battery. Large "gel" batteries or marine batteries are a popular options, and use lead acid chemistry, with about 2 volts per cell. Some Hams, especially those who carry batteries up mountains for Summits on the Air (SOTA) and the like are using various Lithium technologies, such as those used in remote controlled cars. 4 cells in series provide about 14 volts.
Radios can be tuned in one or more ways.
Radios with SSB and/or CW often have a dial. On old radios this tuned a variable capacitor gang, or some other analogue tuning system. In modern radios it operates a "rotary encoder", which increments the frequency in small steps, such as 0.1 or 0.01 kHz, simulating a real dial.
FM radios may also have a knob, which steps through in steps set in the menu, such as 5, maybe 6.25, 10, 12.5, 15, 25, 30, and 50 kHz; and through memories in memory mode. A button may select larger steps, such as MHz.
Some radios also have a keypad, for "direct entry" of frequencies. The buttons may have multiple functions, so for some you press something like: Enter 14.220. On HTs they may assume frequency entry, so just type 147000 for 147 MHz.
If you are transmitting the keypad becomes a DTMF keypad. Holding a numeral key, pressing F and a number, holding F for a moment, then a number may all initiate different settings, such as turning on or off CTCSS, or selecting the sub-tone; setting the step; or selecting +Repeater, -Repeater, or Simplex.
Outside the exam, older radios, especially HTs have thumb-wheels. An example for 2m might have three wheels. We must assume the first 14, for 140 MHz. The wheels then select MHz, hundreds of kHz, and 10s of kHz. A switch marked +5 adds the final 5kHz. Thus 665 means 146.650 MHz. 712+5 is 147.125 MHz, a WICEN channel. Duplex/Simplex and +/- switches, or +/0/- positions control repeater offset, fixed at 600 kHz. Some radios of this type will only transmit on the Ham bands, some require care not to transmit out of band. The Icom IC-2E and IC-2AT are examples, and these have been exactly copied.
Memories are a great way to store repeater channels, tones, and offsets; net frequencies; call channels; ARNSW / WIA news frequencies; and emergency communications group channels. (Some radios have a "Home" memory button which provides rapid access to a call channel, etc.)
Many radios have some form of scanning function, where the radio steps through many channels per second, looking for a frequency where there is a signal. This is initiated either by holding an up or down button (including on a microphone), or pressing a "SCAN" button. Most radios allow both scanning in "VFO" mode, and through memories. It can be used to zip from one end of the band to the other, and tapping the PTT will stop scanning. The exam however tells you to use a memory for a favourite channel.
Beyond the exam, old PMR (commercial or government two-way radios) may have no frequency control, as the use a single receive / transmit crystal pair to operate on one channel, or one repeater; or they may have a dial to select from a small number of such crystal controlled channels or repeaters. Some may have a have a two digit LED display to select repeaters stored in a fixed EPROM or EEPROM memory, programmed on a PC and PROM programmer. More modern PMR radios can be programmed with a PC and cable. The Tait T500 series, such as the T535, are two channel radios which uses a matrix of diodes for programming, with these selected by bridging a pads with solder. While the multi-channel ones can be a cheap way to get on air, the low channel count ones are a good way of having a radio monitoring the local repeater, while using the main shack radio on other bands.
Some modes, such as AM and FM tolerate a moderate amount of frequency error in the transmit frequency, or in tuning of the receiver. In the case of SSB, with no carrier to reference the signal too, if there is a difference between the suppressed carrier frequency, and the tuning of the receiver, the audio will be unnaturally high, or unnaturally low. A knob, called the RIT, or Receiver Incremental Tuning, which tweaks the receiver. In some radios there is a switch for the RIT, allowing it to be stitched in, if one member of a group is off-frequency. 23 cm FM transceivers may also have a RIT, as getting to this frequency means many multiplication steps from the actual VFO frequency, and an error of a few 10s of Hertz can mean an error of several kilohertz, rather than a fraction of a kilohertz on a 2m radio. In SSB CB land this is called the Clarifier, a term used in the exam.
When a radio is tuned to a frequency on which there is no transmission, there speaker will emit noise or hash, which can be rather tiring. To silence the radio, most have a squelch feature. The sensitivity may be set by a knob or by a menu item. Squelch which does not use CTCSS, DCS or tone-burst is called "carrier squelch". It may be called "mute" on some radios. Noise can increase depending on the weather.
Automatic Gain Controlis used in most radios to limit the level of signals within the receiver. This includes keeping the audio level reasonably constant, despite variation in the received signal strength. Some radios have options to change the speed of AGC response to signal variation.
The Noise Blanker at least partially eliminates impulse interference, such as that caused by automotive ignition systems. These may help reduce pulsing interference from "Woodpecker" over-the-horizon radars which operate on the HF bands. While these ended with the end of the "Cold War", they are reported to be back in operation, with Putin's illegal invasion of Ukraine.
You will hopefully have noticed that we have discussed the bandwidth of different modes, such as CW, SSB, AM, and FM.
Depending on the mode, radios have different filters in the IF stage. Better multi-mode radios have several filters which can be switched in, depending on the mode.
For CW (Morse code) the signal's bandwidth is low, but not zero, as the keying on an off causes some bandwidth. The exam indicates the the IF bandwidth should be 500 Hz.
For SSB this is 2.2 to 3 kHz, with the exam listing 2.4 kHz. For AM around 6 kHz is used, and for FM, it is around 16 kHz, or 10.1 kHz in some cases.
It is possible to purchase extra filters (around US$140) to plug into radios, beside, or replacing existing filters. A prime example is the Collins Mechanical Filters, which were by Rockwell Collins, but they have ceased production, with remaining stock sold to Inrad, and running low. The standard filter in the FT-857D is a ceramic filter, listed as 2.2 kHz. This may not be as sharp as the 2.3 kHz Collins / Inrad one, which is considered an upgrade.
There is a Collins / Inrad 500 Hz one for CW, including for the 857D. Adding the CW filter is valuable, as while DSP can provide narrow filtering, if there are strong signals within the 2.2 kHz or whatever SSB channel width, the receiver's gain will be reduced by the AGC, and the weak signal of the station you are trying to hear will also be reduced. If the 500 Hz filter is fitted, and the strong local signal is outside this, the signal should be more easily received, and the DSP has the best possible signal to work with. If you are listening to a broadcast station (MW, SW, or LW), and the signal is good, a wide setting may sound more natural, especially if there is music.
Outside the exam, but when a strong signal near the frequency you are listening to reduces the sensitivity of the receiver, it is said to be "desensitised". This might happen when packet data is being sent from your checkpoint at fairly high power, while your are listening to weak voice stations on the same band.
PCs, running Windows or various Linux versions, can be used for a range of tasks. Those on the exam are: Logging contacts and contact information, sending and/or receiving CW, and generating and decoding digital signals. Logging can involve manually adding all data, or it can be read from the radio via a "CAT", meaning Computer Aided Transceiver interface; serial; or USB. These can also be used to control the radio; and for programming memories.
The radio and PC can be connected via the soundcard, which generates tones to go to the radio's microphone, and converts audio to digital form, where it can be further processed, or converted to text or images if a data or image mode is being received. An alternative is a USB soundcard; or via modems or TNCs. PCs can read the dits and dahs of Morse code; with accuracy depending partly on the sender's "fist", and These multiple uses trigger the "All of the above" option in the relevant question.
The Raspberry Pi single-board computer are affordable computing devices, with a credit-card sized footprint, or smaller, with many applications in Ham radio. The Pi 400 is a version installed within a keyboard, smaller than a 1980s Z-80 BASIC unit, but far more powerful, and replacing composite video with HDMI. There are a wide range of Linux distributions for these.
Removed from the exam in favour of more questions on using sound-card connections, the Terminal Node Controller is a device with includes a processor which assembles text into "packets", and a modem which converts these to audio tones, and keys the radio. It also demodulates the tones to packets, and so to text. Some contain message storage, and other smart functions. They connect to PCs (or Commodores, or MicroBees) via RS-323C; or to modern PCs via a USB adaptor.
Likewise, from the days of DOS PCs, is the Baycom modem and software, where a small PCB contained a modem chip, but packet assembly and decoding was done in software.
There are a range of mobile 'phone apps for Amateur Radio too.
Macs can also be used, but don't ask me how...
MMDVM (Multi-Mode Digital Voice Modem) Hotspot and Jumbospot are small devices with an antenna which allows a handheld or other radio to connect to D-STAR, P25, DMR networks. Most work on both UHF or VHF bands. Yaesu's System Fusion (C4FM) and NXDN may also be available. The hotspot board plugs into a Raspberry Pi Zero or full-size Raspberry Pi. The better option includes a small OLED display. A setup costs under A$100, or somewhat more if bought fully set up.
They are powered by a Micro USB charger or powerbank, and require a WiFi connection. Range may be a few hundred metres with a resonant antenna.
While home WiFi is typically used, a mobile 'phone's WiFi hotspot function can also be used.
SWR meter, regular power meters, and directional wattmeters, are placed in series with feedline, between transmitter and antenna.
This is because they are generally used to assess the antenna and feedline combination for SWR.
Actual exam questions, from the published NCVEC Technician pool.
Which of the following is an appropriate power supply rating for a typical 50 watt output mobile FM transceiver?
A. 24.0 volts at 4 amperes
B. 13.8 volts at 4 amperes
C. 24.0 volts at 12 amperes
D. 13.8 volts at 12 amperes
The standard smaller motor vehicle has a battery voltage of around 13.8 volts while the engine is operating, or while the high voltage traction battery is charging the "12 volt" accessory battery. Before you put 50 over 13.8, and get a fairly small current, we must remember that radios are not that efficient. Lets say it is 50% efficient, so we need 100 watts. Put 100 / 13.8, and get about 7.25 amps. As the supply's capacity must exceed the current draw of the radio, so the 12 amp unit is needed, answer D.
An oldie, but a goodie, the Yaesu FT-212RH requires 10 amps for its 45 watt output. Icom's 50 watt D-Star rigs can chew through 13 Amps! Always read the manual.
Which of the following should be considered when selecting an accessory SWR meter?
A. The frequency and power level at which the measurements will be made
B. The distance that the meter will be located from the antenna
C. The types of modulation being used at the station
D. All these choices are correct
The frequency and power levels used are the primary factors in choosing a meter, answer A.
The examiner assumes the station equipment is capable of producing a CW, AM, or FM signal, or similar, with a constant power level. However, there are peak reading meters, suitable for use with SSB. Ditto on meters with remote sensing bridges, even commercial products where a broadcast engineer can monitor the forward and reflected power at broadcast sites, and thus SWR. Despite this, the answer for the paper is A.
Why are short, heavy-gauge wires used for a transceiver’s DC power connection?
A. To minimize voltage drop when transmitting
B. To provide a good counterpoise for the antenna
C. To avoid RF interference
D. All these choices are correct
On transmit some radios draw quite high current while transmitting, and thus leads need to be short and heavy to avoid voltage drop. answer A.
The previous version of this question mentioned improper operation, and certainly excessive length of inadequate wire, including that to te vehicle's lighter socket, can cause a FT-857D to misbehave. Thinking back to Ohm's law, heavy, short cable has lower resistance, and thus a lower voltage drop. Hams do at times replace the standard cabling with a shorter and/or chunkier one.
How are the transceiver audio input and output connected in a station configured to operate using FT8?
A. To a computer running a terminal program and connected to a terminal node controller unit
B. To the audio input and output of a computer running WSJT-X software
C. To an FT8 conversion unit, a keyboard, and a computer monitor
D. To a computer connected to the FT8converter.com website
The audio output of the radio is connected to the input of the computer. The PC or Raspberry Pi would need to run software, such as WSJT-X. Answer B.
PCs now usually include a sound-card on the motherboard, as do laptops. These may be marked "line-in" or "microphone". Outputs may be "line-out", or more often a headphone output. The "RIGblaster" products replace the sound-card, and include a USB interface to the PC, and a radio control interface. Low cost USB "sound-cards" are also available, meaning the existing one can be used for speakers and a microphone, and the external device for the radio interface.
A naughty boy (that would be your author) just sneakily registered the until-now bogus FT8converter.com domain, which points at this site.
Where should an RF power meter be installed?
A. In the feed line, between the transmitter and antenna
B. At the power supply output
C. In parallel with the push-to-talk line and the antenna
D. In the power supply cable, as close as possible to the radio
It goes between the transmitter and antenna, in the feed-line, answer A.
Which of the following connections might be used between a voice transceiver and a computer for digital operation?
A. Receive and transmit mode, status, and location
B. Antenna and RF power
C. Receive audio, transmit audio, and push-to-talk (PTT)
D. NMEA GPS location and DC power
The two audio connections, and the PTT line are connected between the radio and the computer, answer C.
Which of the following connections is made between a computer and a transceiver to use computer software
when operating digital modes?
A. Computer "line out" to transceiver push-to-talk
B. Computer "line in" to transceiver push-to-talk
C. Computer "line in" to transceiver speaker connector
D. Computer "line out" to transceiver speaker connector
The computer's audio "line in", is connected to the radio's speaker output, answer C.
This allows the computer to decode a range of digital communications, and things like SSTV, weather fax, pager messages, and Morse (if the radio has a suitable mode). Two soundcards allows you to decode CODEC2 digital voice and hear the audio on the PC's speaker.
Note that sending data, SSTV, or CODEC2 audio requires a connection from the PC's audio out to the radio's audio input; and a PTT line, unless VOX is used.
Which of the following conductors is preferred for bonding at RF?
A. Copper braid removed from coaxial cable
B. Steel wire
C. Twisted-pair cable
D. Flat copper strap
Flat copper strap has both low DC resistance, and a large surface area, so conducts RF well, answer D.
At home use includes connecting ground connections on equipment to an earth plate, and from this to the ground rods. Bonding car bonnets / hoods, boot / trunk lids, and exhaust components to the body can help reduce electrical noise in vehicles.
Coax Braid probably has inadequate cross-sectional area, as well as not being as wide as maybe be desirable. Steel has less conductivity (more resistance) than copper.
How can you determine the length of time that equipment can be powered from a battery?
A. Divide the watt-hour rating of the battery by the peak power consumption of the equipment
B. Divide the battery ampere-hour rating by the average current draw of the equipment
C. Multiply the watts per hour consumed by the equipment by the battery power rating
D. Multiply the square of the current rating of the battery by the input resistance of the equipment
If you have a 50 amp-hour battery, and a radio with an average consumption of 5 amps, 50 / 5 = 10, saying that the radio can be run for 10 hours. Capacity divided by the current draw provides the time the equipment can run, answer B.
What function is performed with a transceiver and a digital mode hot spot?
A. Communication using digital voice or data systems via the internet
B. FT8 digital communications via AFSK
C. RTTY encoding and decoding without a computer
D. High-speed digital communications for meteor scatter
A hotspot allows communication using digital voice (or data) modes via the internet, without using a normal repeater, answer A.
Where should the negative power return of a mobile transceiver be connected in a vehicle?
A. At the 12 volt battery chassis ground
B. At the antenna mount
C. To any metal part of the vehicle
D. Through the transceiver’s mounting bracket
The negative line from the radio should go to the grounding point near the (12 volt) battery, answer A.
Effective and correct grounding prevents excess return currents flowing through the other points mentioned.
What is an electronic keyer?
A. A device for switching antennas from transmit to receive
B. A device for voice activated switching from receive to transmit
C. A device that assists in manual sending of Morse code
D. An interlock to prevent unauthorized use of a radio
This is a unit which assists in sending Morse code, answer C.
What is the effect of excessive microphone gain on SSB transmissions?
A. Frequency instability
B. Distorted transmitted audio
C. Increased SWR
D. All these choices are correct
To high a microphone gain setting can cause the transmitted audio to become distorted, answer B.
Which of the following can be used to enter a transceiver’s operating frequency?
A. The keypad or VFO knob
B. The CTCSS or DTMF encoder
C. The Automatic Frequency Control
D. All of these choices are correct
The keypad or VFO dial, answer A, are generally two ways to enter or select frequency.
AFC is an old drift compensation system.
How is squelch adjusted so that a weak FM signal can be heard?
A. Set the squelch threshold so that receiver output audio is on all the time
B. Turn up the audio level until it overcomes the squelch threshold
C. Turn on the anti-squelch function
D. Enable squelch enhancement
If it is not possible to set the squelch knob (or digital setting) so that it reliably mutes and un-mutes, set it so that the audio is on lall teh time. Answer A.
What is a way to enable quick access to a favorite frequency or channel on your transceiver?
A. Enable the frequency offset
B. Store it in a memory channel
C. Enable the VOX
D. Use the scan mode to select the desired frequency
Store the favourite frequency in the radio's memory, answer B.
What does the scanning function of an FM transceiver do?
A. Checks incoming signal deviation
B. Prevents interference to nearby repeaters
C. Tunes through a range of frequencies to check for activity
D. Checks for messages left on a digital bulletin board
Scan searches a range of frequencies for activity, answer C.
Which of the following controls could be used if the voice pitch of a single-sideband signal returning to your CQ call seems too high or low?
A. The AGC or limiter
B. The bandwidth selection
C. The tone squelch
D. The RIT or Clarifier
The RIT or clarifier adjusts only the receiver, without affecting the transmitter, answer D.
Some radios allow the RIT to be set for the one station in a net who is off channel, then switched in and out as needed.
What does a DMR “code plug” contain?
A. Your call sign in CW for automatic identification
B. Access information for repeaters and talkgroups
C. The codec for digitizing audio
D. The DMR software version
A codeplug contains repeater and talkgroup settings.
What is the advantage of having multiple receive bandwidth choices on a multimode transceiver?
A. Permits monitoring several modes at once by selecting a separate filter for each mode
B. Permits noise or interference reduction by selecting a bandwidth matching the mode
C. Increases the number of frequencies that can be stored in memory
D. Increases the amount of offset between receive and transmit frequencies
It allows appropriate filters to match the mode, and so reduces noise and interference, answer B.
If using a SSB filter for CW, then signals from stations on several nearby frequencies may be audible, as may more noise.
How is a specific group of stations selected on a digital voice transceiver?
A. By retrieving the frequencies from transceiver memory
B. By enabling the group’s CTCSS tone
C. By entering the group’s identification code
D. By activating automatic identification
Digital modes may use codes to identify groups of users. Entering such a code allows you to speak to stations in this group, be it residents of your state, or people using a particular language, or an emergency communications group.
Which of the following receiver filter bandwidths provides the best signal-to-noise ratio for SSB reception?
A. 500 Hz
B. 1000 Hz
C. 2400 Hz
D. 5000 Hz
2400 Hz (2.4 kHz) is the best option, answer C.
Your radio may have slightly different figure, such as 2.3 kHz.
Which of the following must be programmed into a D-STAR digital transceiver before transmitting?
A. Your call sign
B. Your output power
C. The codec type being used
D. All these choices are correct
The protocol requires that the user's callsign be programmed into the radio, answer A.
What is the result of tuning an FM receiver above or below a signal’s frequency?
A. Change in audio pitch
B. Sideband inversion
C. Generation of a heterodyne tone
D. Distortion of the signal’s audio
If an FM receiver is mistuned the audio will be distorted, answer D.
On to the final page: Operating 4
You can find links to lots more on the Learning Material page.
This has taken a fair bit of work to write, so if you have found this useful, there is a "tip jar" below.
Written by Julian Sortland, VK2YJS & AG6LE, March.
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