AMATEUR RADIO TECHNICIAN CLASS LICENSE COURSE (FOR USE JULY 1, 2018 TO
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AMATEUR RADIO TECHNICIAN CLASS LICENSE COURSE (FOR USE JULY 1, 2018 TO JUNE 30, 2022) PREPARED BY: EARL PAAZIG W8BR
MOST COMMON TERMS USED IN QUESTION POOL amateur antenna band circuit communication control current electrical FCC frequency license operator power radio repeater signals station voltage
EXAM SUBJECT CONTENT Sub-element Exam Questions T1 - FCC Rules 6 T2 - Operating Procedures 3 T3 - Radio wave characteristics 3 T4 - Amateur radio practices 2 T5 - Electrical principles 4 T6 - Electrical components 4 T7 - Station equipment 4 T8 - Modulation modes 4 T9 – Antennas and feedlines 2 T0 – Electrical Safety 3 Total 35
SUBELEMENT T7 – STATION EQUIPMENT 4 Exam Questions - 4 Groups
T7A – STATION EQUIPMENT
TYPICAL STATION CONFIGURATION A STATION MAY BE CONFIGURED TO MEET THE NEED! * Typically every effort should be placed with ensuring that all station equipment is bonded to a common station ground and requirements of the National Electrical Code are met. SWR/Power Meter Radio Microphone Morse Code Key External Power Supply Antenna Switch Dummy Load *Station Ground Computer w/ Sound Card For Digital Modes and/or Computerized Station Control Sound Card Interface Could be TNC in a packet radio station. Speaker or Headphones will be connected to Interface, Computer, or Radio depending on application. Tuner and/or Filter Speaker
RECEIVERS Sensitivity is the term which describes the ability of a receiver to detect the presence of a signal. Selectivity is the term which describes the ability of a receiver to discriminate between multiple signals.
TRANSMITTERS An Oscillator circuit generates a signal at a specific frequency. A Mixer is used to convert a radio signal from one frequency to another.
TRANSCEIVERS A transceiver is a unit combining the functions of a transmitter and a receiver. The push-to-talk (PTT) function is what switches between receive and transmit.
S-METER The S - meter gives a relative signal strength reading of a received signal. MICROPHONE GAIN FREQUENCY HF TRANSCEIVER NOISE BLANKER SQUELCH MODE VFO MEMORY CHANNEL IF SHIFT
MODULATION Modulation describes combining speech with an RF carrier signal. Amplitude Modulation Demo Frequency Modulation Demo http://www.wirebiters.com/wp-content/uploads/2014/01/am-modulation.jpg
TRANSVERTERS A Transverter device converts the RF input and output of a transceiver to another band. For example: RF Input of 10 MHZ with RF Output of 20 MHz.
TRANSMIT AND RECEIVE AMPLIFIERS The function of the SSB/CW-FM switch on a VHF power amplifier is to set the amplifier for proper operation in the selected mode. This switch when set to SSB adds a small delay before switching back to RX after a transmission. When using SSB this helps prevent the amplifiers RX TX relay from constantly switching between RX and TX during pauses in speech as there is no RF carrier to hold the relay open. In FM/AM modes this is not necessary and the switch position can be set to FM. https://www.mirageamp.com/Product.php?productid B-2518-G
TRANSMIT AND RECEIVE AMPLIFIERS An RF power amplifier device increases the low-power output from a handheld transceiver. An RF preamplifier is installed between the antenna and receiver. https://www.mirageamp.com/Product.php?productid B-2518-G
T7B – COMMON TRANSMITTER AND RECEIVER PROBLEMS
INTERFERENCE AND CONSUMER ELECTRONICS You can reduce or eliminate interference from an amateur transmitter to a nearby telephone by putting an RF filter on the telephone. https://www.centurylink.com/home/help/home-phone/get-rid-of-annoying-noises-on-your-phone-line/ jcr content/par/columncontrolmaster 183488998/col0/image copy.img.png/1470438192489.png
PART 15 DEVICES A Part 15 device is an unlicensed device that may emit lowpowered radio signals on frequencies used by a licensed service. http://www.arrl.org/part-15-radio-frequency-devices https://fccid.io/images/device/DC9/-OVS01/ID-Label-Location-Info-F78F5651.jpg Other Radio Services CFR 47: PART 80 - STATIONS IN THE MARITIME SE RVICES (§§ 80.1 - 80.1252) PART 87 - AVIATION SERVICES (§§ 87.1 - 8 7.529) PART 90 - PRIVATE LAND MOBILE RADIO SERVICES (§§ 90.1 - 90.1338) PART 95 - PERSONAL RADIO SERVICES (§§ 95.100 - 95.3385) PART 96 - CITIZENS BROADBAND RADIO S ERVICE (§§ 96.1 - 96.67) PART 97 - AMATEUR RADIO SERVICE (§§ 97.1 - 97.527) PART 101 - FIXED MICROWAVE SERVICES (§§ 101.1 - 101.1527)
OFF FREQUENCY SIGNALS AND DISTORTION If you receive a report that your audio signal through the repeater is distorted or unintelligible: Your transmitter is slightly off frequency Your batteries are running low You are in a bad location (All of these choices are correct)
SYMPTOMS OF OVERLOAD AND OVERDRIVE A broadcast AM or FM radio could receive an amateur radio transmission unintentionally if the receiver is unable to reject strong signals outside the AM or FM band.
OVER-MODULATION If you are told your FM handheld or mobile transceiver is overdeviating, talk farther away from the microphone. Tip: Sometimes just rotating the microphone to talk across it, will often fix it too.
RF FEEDBACK A symptom of RF feedback in a transmitter or transceiver is reports of garbled, distorted, or unintelligible voice transmissions.
CAUSES OF INTERFERENCE The first step to resolve cable TV interference from your ham radio transmission is be sure all TV coaxial connectors are installed properly.
CAUSES OF INTERFERENCE All of the following can cause radio frequency interference: Fundamental overload Harmonics Spurious emissions (All of these choices are correct)
CAUSES OF INTERFERENCE If a neighbor tells you that your station’s transmissions are interfering with their radio or TV reception make sure that your station is functioning properly and that it does not cause interference to your own radio or television when it is tuned to the same channel.
Overload of a non-amateur radio or TV receiver by an amateur signal can be reduced or eliminated by blocking the amateur signal with a filter at the antenna input of the affected receiver. This is typically known as a high pass filter. It passes signals above 50 MHz but attenuates signals below 50 MHz by 30 to 45 dB. https://www.antennas-amplifiers.com/image/cache/catalog/-other/rfi-filter/RFI-Filter-ham-radio-Interference-Choke-720x400.jpg CAUSES OF INTERFERENCE
CAUSES OF INTERFERENCE Rejected Rejected Passed Passed Rejected Passed Rejected A Band-reject filter, a.k.a. Band Stop filter, can reduce overload to a VHF transceiver from a nearby FM broadcast station. https://www.norwegiancreations.com/wp-content/uploads/2016/03/filters.png https://rf-tools.com/lc-filter/ Passed Rejected Passed
CAUSES OF INTERFERENCE If something in a neighbor’s home is causing harmful interference to your amateur station: Work with your neighbor to identify the offending device Politely inform your neighbor about the rules that prohibit the use of devices that cause interference Check your station and make sure it meets the standards of good amateur practice (All of these choices are correct)
T7C – ANTENNA MEASUREMENTS AND TROUBLESHOOTING
STANDING WAVE RATIO (SWR) A standing wave ratio (SWR) is a measure of how well a load is matched to a transmission line. https://upload.wikimedia.org/wikipedia/commons/thumb/7/7d/Standing wave 2.gif/350px-Standing wave 2.gif
STANDING WAVE RATIO (SWR) A reading of 1 to 1 (1:1) on an SWR meter indicates a perfect impedance match between the antenna and the feed line. An SWR reading of 4 to 1 (4:1) indicates an impedance mismatch.
Z0 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 ZL 50 75 100 125 150 200 250 300 500 1000 2000 3000 4000 5000 10000 20000 VSWR 1.0 1.5 2.0 2.5 3.0 4.0 5.0 6.0 10 20 40 60 80 100 200 400 Reflection Coefficient (S11) 0.000 0.200 0.333 0.429 0.500 0.600 0.667 0.714 0.818 0.905 0.951 0.967 0.975 0.980 0.990 0.995 Return Loss (db) 14.0 9.5 7.4 6.0 4.4 3.5 2.9 1.7 0.9 0.4 0.3 0.2 0.2 0.1 0.0 Reflected Power % 0.0 4.0 11.1 18.4 25.0 36.0 44.4 51.0 66.9 81.9 90.5 93.6 95.1 96.1 98.0 99.0 Perfect Impedance Match Tuning Range. Antennas are often spec’d for 2:1 SWR Bandwidth. Transceivers with builtin Antenna Tuners usually work in 3:1 or less range. Impedance Mismatch More than 25% of RF signal reflected back to radio indicates a severe mismatch that needs mitigated.
STANDING WAVE RATIO (SWR) Most solid-state amateur radio transmitters reduce output power as SWR increases to protect the output amplifier transistors. Power lost in a feed line is converted into heat.
MEASURING SWR A Directional wattmeter could be used to determine if a feed line and antenna are properly matched. https://en.wikipedia.org/wiki/Standing wave ratio#/media/File:Bird 43 RF power meter.jpg An antenna analyzer can be used to determine if an antenna is resonant at the desired operating frequency.
DUMMY LOADS A dummy load consists of a noninductive resistor and a heat sink. The primary purpose of a dummy load is to prevent transmitting signals over the air when making tests. https://static.dxengineering.com/global/images/prod/xlarge/mfj-264 us xl.jpg https://en.wikipedia.org/wiki/Dummy load#/media/File:Cantenna.JPG
COAXIAL CABLES AND CAUSES OF FEED LINE FAILURES A disadvantage of air core coaxial cable when compared to foam or solid dielectric types is it requires special techniques to prevent water absorption. Moisture is a problem!
COAXIAL CABLES AND CAUSES OF FEED LINE FAILURES Moisture contamination is the most common cause for failure of coaxial cables. The outer jacket of coaxial cable needs to be resistant to ultraviolet light because ultraviolet light can damage the jacket and allow water to enter the cable. https://en.wikipedia.org/wiki/Coaxial cable#/media/File:Coaxial cable cutaway.svg
T7D – BASIC REPAIR AND TESTING
SOLDERING Rosin-core solder is best for radio and electronic use. A characteristic appearance of a cold solder joint is a grainy or dull surface. Note: This is not desired. https://learn.adafruit.com/assets/1978
Analog Multimeter Digital Auto-ranging Multimeter
USING AND CONNECTING A VOLTMETER A voltmeter is used to measure electric potential or electromotive force. The correct way to connect a voltmeter to a circuit is in parallel with the circuit. https://upload.wikimedia.org/wikipedia/commons/thumb/f/fb/VoltmeterSymbol.svg/1280px-VoltmeterSymbol.svg.png
USING AND CONNECTING AN AMMETER A simple ammeter is connected in series with the circuit. An ammeter is used to measure electric current. https://upload.wikimedia.org/wikipedia/commons/thumb/f/fb/VoltmeterSymbol.svg/1280px-VoltmeterSymbol.svg.png
USING AND CONNECTING AN OHMMETER An ohmmeter is used to measure resistance. Connect it like a voltmeter but make sure battery or power source is off! https://upload.wikimedia.org/wikipedia/commons/thumb/f/fb/VoltmeterSymbol.svg/1280px-VoltmeterSymbol.svg.png
PRECAUTIONS Attempting to measure voltage when using the resistance setting might damage a multimeter. Precautions should be taken when measuring circuit resistance with an ohmmeter -- ensure that the circuit is not powered. Precautions should be taken when measuring high voltages with a voltmeter – ensure that the voltmeter and leads are rated for use at the voltages to be measured.
USE OF MEASURING EQUIPMENT Voltage and resistance are commonly made using a multimeter. When an ohmmeter, connected across an unpowered circuit, initially indicates a low resistance and then shows increasing resistance with time, usually, the circuit contains a large capacitor.
Q&A END OF SECTION
SOURCES USED Study Guide developed by Earl, W8BR, based upon the publicly available question pool Content and graphics previously developed study guides by Earl, N8KBR Special Notes are provided to supplemental information. https://upload.wikimedia.org/wikipedia/commons/thumb/7/7d/Standing wave 2.gif/350px-Standing wave 2.gif https://en.wikipedia.org/wiki/Standing wave ratio#/media/File:Bird 43 RF power meter.jpg https://en.wikipedia.org/wiki/Dummy load#/media/File:Cantenna.JPG https://en.wikipedia.org/wiki/Coaxial cable#/media/File:Coaxial cable cutaway.svg https://learn.adafruit.com/assets/1978 https://upload.wikimedia.org/wikipedia/commons/thumb/f/fb/VoltmeterSymbol.svg/1280px-VoltmeterSymbol.svg.png
