Technician License Class Chapter 5 Amateur Radio Equipment

Generalized Transceiver Categories Single Band VHF or UHF FM Dual Band VHF/UHF FM Multimode VHF/UHF Multiband HF and VHF/UHF Handheld (HT) FM (VHF, UHF, or Both)

Single Band FM Transceiver Probably the most common starter rig. Operates from 12 volts dc, requires external power supply. Requires an external antenna. Can be operated mobile or as a base station. Usually either 2 meters or 70 cm bands. Up to approximately 65 watts output.

Dual Band FM Transceiver Same as the single band transceiver but includes additional band(s). Most common are 2 meter and 70 cm bands. Could add 6 meters, 222 MHz or 1.2 GHz. Depending on antenna connectors, might require separate coax for each band or a duplexer for single coax.

Multimode Transceiver Can be single or multiband. Main difference is that these rigs can operate on all major modes SSB/AM/FM, CW, Data, RTTY etc. More features add complexity and cost. Most flexible type of rig. It will allow you to explore new modes as you gain experience. Best for weak-signal communications.

Multiband HF Transceiver Covers many bands – can be limited to HF or can be HF/VHF/UHF. Also covers all modes. Frequently 100 watts on HF, some power limitations on high bands (50 watts). Larger units may have internal power supplies, smaller units need external power supply (13.8 V).

Handheld (HT) Transceiver Small handheld FM units. Can be single band or dual band. Limited power (usually 5 watts or less). External RF power amplifier. Includes power (battery) and antenna in one package. An attractive first starter rig – but make sure it is what you want.

Rig Vocabulary We will now go through some jargon and vocabulary specific to the functions and controls of a transmitter and receiver. This is a way to discuss how to operate a transceiver. These controls, though separate, are combined in a transceiver.

Transmitter Controls & Functions Main tuning dial (both TX and RX): Controls the frequency selection via the variable frequency oscillator (VFO). Could be an actual dial or key pad or programmed channels. Variable frequency step size (tuning rate, resolution). Could have more than one VFO (control more that one frequency at a time).

Transmitter Controls & Functions Mode selector (both TX and RX for multimode rigs). Multimode rigs only. AM/FM/SSB (LSB or USB) CW Data (RTTY) Could be automatic. Based on recognized band plan.

Transmitter Controls & Functions Microphone controls Gain How loudly you need to talk to be heard. Speech Compressor or Speech Processor Compacting your speech into a narrow amplitude range to enhance “punch.”

Transmitter Controls & Functions Microphone controls Too much gain or compression can cause problems. Over-deviation Over-modulation Splatter

Transmitter Controls & Functions Automatic Level Control (ALC). Automatically limits transmitter drive (output level) to prevent problems associated with too much gain or compression. Also can control external power amplifier operation.

Transmitter Controls & Functions Transmitter on/off. Push-to-Talk (PTT). Voice-Operated Transmission (VOX). VOX Gain. VOX Delay. Anti-VOX. Key Jack.

Transmitter Controls & Functions Microphones (Mic). Hand microphones. Desk microphones. Pre-amplified desk microphones. Speaker-microphones. Headsets or boom-sets. Internal microphones. Some microphones include PTT & power. Not all microphones use same connector. If same connector, not all wired the same.

Transmitter Controls & Functions Morse Keys. Straight key. Semi-automatic (Bug). Electronic keyer and paddle. Electronic keyer often built into transceiver. Computer keyboard.

Transmitter Controls & Functions

Transmitter Controls & Functions Transmit Meter. Output power. ALC Level. SWR Final amplifier stage current.

Receiver Controls & Functions AF Gain or Volume Controls the audio level to the speaker or headphones. RF Gain Controls the strength of radio signal entering the receiver. Used to limit (attenuate) very strong local signals. Usually operated in the full-open position. Not always best practice.

Receiver Controls & Functions Automatic Gain Control (AGC) Automatically limits the incoming signals during signal (voice) peaks. Prevents peaks from capturing the receiver and limiting reception of lower level portions of the incoming signal. Fast setting for CW. Slow settings for SSB and AM. Not used for FM.

Receiver Controls & Functions Squelch. Turns off audio to speaker when signal is not present. Open – allows very weak signals to pass through (along with noise). Tight – allows only the strongest signals to pass through. Advance the squelch control until the noise just disappears. Used primarily for FM.

Receiver Controls & Functions Filters Bandwidth filter Used to narrow the width of signal that is passed. Can attenuate adjacent interference. Notch filter Very narrow filter that can be moved over an interfering signal to attenuate it. Noise blanker or limiter Limits signal spikes that are frequently associated with random naturally generated noise.

Receiver Controls & Functions Receiver Incremental Tuning (RIT). a.k.a. – Clarifier. Used to adjust receiver frequency a small amount without changing the transmit frequency. A single-sideband signal sounds “funny” if slightly off frequency.

Receiver Controls & Functions Receive Meter. Signal strength. Measured in “S” units. S1 to S9, dB over S9. S9 = 1 mV at antenna terminals. S9 = -73 dBm. 0 dBm = 1 mW into 50Ω load. Increase of 1 S-unit = Increase of 6 dB.

Receiver Controls & Functions Receivers can be limited to ham bands or can cover other parts of the spectrum. General coverage receivers cover a wide area of the spectrum and can be used for shortwave listening (SWL).

Handheld Transceivers Single, dual and multiband versions (with increasing cost and complexity). Some have expanded receiver coverage (wide-band receive). Very portable and self-contained. Internal microphone and speaker. Rubber duck antenna. Battery powered.

Handheld Transceivers Nice to have handheld accessories: Extra battery packs. Drop-in, fast charger. Extended antenna. External microphone and speaker. Headset.

T2B03 - Which of the following describes the muting of receiver audio controlled solely by the presence or absence of an RF signal? A. Tone squelch B. Carrier squelch C. CTCSS D. Modulated carrier

T4A01 - Which of the following is true concerning the microphone connectors on amateur transceivers? A. All transceivers use the same microphone connector type B. Some connectors include push-to-talk and voltages for powering the microphone C. All transceivers using the same connector type are wired identically D. Un-keyed connectors allow any microphone to be connected

T4B01 - What may happen if a transmitter is operated with the microphone gain set too high? A. The output power might be too high B. The output signal might become distorted C. The frequency might vary D. The SWR might increase

T4B02 - Which of the following can be used to enter the operating frequency on a modern transceiver? A. The keypad or VFO knob B. The CTCSS or DTMF encoder C. The Automatic Frequency Control D. All of these choices are correct

T4B03 - What is the purpose of a squelch control on a transceiver? A. To set the highest level of volume desired B. To set the transmitter power level C. To adjust the automatic gain control D. To mute receiver output noise when no signal is being received

T4B04 - What is a way to enable quick access to a favorite frequency on your transceiver? A. Enable the CTCSS tones B. Store the frequency in a memory channel C. Disable the CTCSS tones D. Use the scan mode to select the desired frequency

T4B05 - Which of the following would reduce ignition interference to a receiver? A. Change frequency slightly B. Decrease the squelch setting C. Turn on the noise blanker D. Use the RIT control

T4B07 - What does the term “RIT” mean? A. Receiver Input Tone B. Receiver Incremental Tuning C. Receiver Inverter Test D. Remote Input Transmitter

T4B08 - What is the advantage of having multiple receive bandwidth choices on a multimode transceiver? A. Permits monitoring several modes at once 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

T4B09 - Which of the following is an appropriate receive filter to select in order to minimize noise and interference for SSB reception? A. 500 Hz B. 1000 Hz C. 2400 Hz D. 5000 Hz

T4B10 - Which of the following is an appropriate receive filter to select in order to minimize noise and interference for CW reception? A. 500 Hz B. 1000 Hz C. 2400 Hz D. 5000 Hz

T7A09 - Which of the following devices is most useful for VHF weak-signal communication? A. A quarter-wave vertical antenna B. A multi-mode VHF transceiver C. An omni-directional antenna D. A mobile VHF FM transceiver

T7A10 - What device increases the low-power output from a handheld transceiver? A. A voltage divider B. An RF power amplifier C. An impedance network D. A voltage regulator

T7B01 - What can you do if you are told your FM handheld or mobile transceiver is over deviating? A. Talk louder into the microphone B. Let the transceiver cool off C. Change to a higher power level D. Talk farther away from the microphone

T8D10 - Which of the following can be used to transmit CW in the amateur bands? A. Straight Key B. Electronic Keyer C. Computer Keyboard D. All of these choices are correct

Data Modes a.k.a. – Digital modes. Connecting computers via ham radio. Some systems use radio to connect to internet gateways. The bulk of the work is done by specialized modems or computer software/sound card. Terminal Node Controller (TNC). Multiple Protocol Controller (MPC).

Digital Modes Error Correction. Bit Error Rate (BER). BER = number of bit errors / total number of bits. Forward Error Correction (FEC). Adds extra information so that data can be reconstructed. (e.g. - MFSK-16) Automatic Repeat Request (ARQ). If error detected, asks sending station to retransmit data. (e.g. - packet radio)

Popular Digital Modes Radioteletype (RTTY) PSK31. Packet Radio. Automatic Packet Reporting System (APRS). Winlink. And many, many more….

Automatic Packet Reporting System

Data Station Setup

Internet Gateway

T4A06 - Which of the following would be connected between a transceiver and computer in a packet radio station? A. Transmatch B. Mixer C. Terminal node controller D. Antenna

T4A07 - How is the computer’s sound card used when conducting digital communications using a computer? A. The sound card communicates between the computer CPU and the video display B. The sound card records the audio frequency for video display C. The sound card provides audio to the microphone input and converts received audio to digital form D. All of these choices are correct

T7B12 - What does the acronym “BER” mean when applied to digital communications systems? A. Baud Enhancement Recovery B. Baud Error Removal C. Bit Error Rate D. Bit Exponent Resource

T8C11 - What name is given to an amateur radio station that is used to connect other amateur stations to the Internet? A. A gateway B. A repeater C. A digipeater D. A beacon

T8D01 - Which of the following is an example of a digital communications method? A. Packet B. PSK31 C. MFSK D. All of these choices are correct

T8D02 - What does the term APRS mean? A. Automatic Position Reporting System B. Associated Public Radio System C. Auto Planning Radio Set-up D. Advanced Polar Radio System NOTE: This is an error in the question pool. The correct answer should read: “Automatic Packet Reporting System”.

T8D03 - Which of the following is normally used when sending automatic location reports via amateur radio? A. A connection to the vehicle speedometer B. A WWV receiver C. A connection to a broadcast FM sub-carrier receiver D. A Global Positioning System receiver

T8D06 - What does the abbreviation PSK mean? A. Pulse Shift Keying B. Phase Shift Keying C. Packet Short Keying D. Phased Slide Keying

T8D07 - What is PSK31? A. A high-rate data transmission mode B. A method of reducing noise interference to FM signals C. A method of compressing digital television signal D. A low-rate data transmission mode

T8D08 - Which of the following may be included in packet transmissions? A. A check sum which permits error corrections B. A header which contains the call sign of the station to which the information is being sent C. Automatic repeat request in case of error D. All of these choices are correct

T8D09 - What code is used when sending CW in the amateur bands? A. Baudot B. Hamming C. International Morse D. Gray

T8D11 - What is a “parity” bit? A. A control code required for automatic position reporting B. A timing bit used to ensure equal sharing of a frequency C. An extra code element used to detect errors in received data D. A “triple width” bit used to signal the end of a character

Break

Power Supplies House power is ~120 VAC, 60 Hz. Most modern radios require ~12 VDC. Actually 13.8 VDC. A power supply is a device that converts 120 VAC power to the desired DC voltage or voltages.

Power Supplies Unregulated supply. Regulated supply. Simple circuit. Voltage can vary over a wide range with changing load current. Regulated supply. More complex circuit. Voltage is nearly constant with changing load. Modern rigs work best with a regulated power supply.

Power Supplies Regulated Power Supplies. Linear. Large & heavy. Inefficient. Generate heat. Easy to repair. Less expensive.

Power Supplies Regulated Power Supplies. Switching. Small & lightweight. Very efficient. More difficult to repair. More expensive.

Power Supplies Ratings: Continuous current. Intermittent current. How much current can be supplied over the long term. Intermittent current. How much surge current can be supplied over the short term. Voltage regulation. How well the power supply can handle rapid current changes.

Mobile Power Wiring Fuse BOTH positive & negative leads close to the power connection. Connect negative lead to battery or to battery ground connection. Use grommets or sleeves to protect wires where they pass through firewall. Do NOT assume that all metal body parts are grounded.

Mobile Power Wiring Mobile installations can suffer from noise from the vehicle electrical system. Receive Interference. Ignition noise. Regular noise pulses when spark plugs fire. Alternator whine. High-pitched whine that varies in frequency with engine speed. Transmit Interference.

Generators & Inverters For emergency & portable operations, commercial AC power may not be available. Generator. Converts mechanical energy to electrical energy. Inverter. Converts DC voltage to AC voltage.

Generators & Inverters For emergency & portable operations, commercial AC power may not be available. Generator. Converts mechanical energy to AC or DC electrical energy. Inverter. Converts DC voltage to AC voltage.

Generators & Inverters Motor-Generator Sets. AC generator connected to small gasoline engine. Old technology. Less Expensive. Typically very noisy. Output voltage not pure sine wave. Distorted output may damage sensitive electronic equipment.

Generators & Inverters Motor-Generator-Inverter Sets. DC generator connected to small gasoline engine & DC voltage fed to an inverter. New technology. More expensive. Relatively quiet. Output voltage is pure sine wave. Safe for sensitive electronic equipment.

Generators & Inverters

T4A03 - Which is a good reason to use a regulated power supply for communications equipment? A. It prevents voltage fluctuations from reaching sensitive circuits B. A regulated power supply has FCC approval C. A fuse or circuit breaker regulates the power D. Power consumption is independent of load

T4A10 - What is the source of a high-pitched whine that varies with engine speed in a mobile transceiver’s receive audio? A. The ignition system B. The alternator C. The electric fuel pump D. Anti-lock braking system controllers

T4A11 - Where should a mobile transceiver’s power negative connection be made? A. At the battery or engine block ground strap B. At the antenna mount C. To any metal part of the vehicle D. Through the transceiver’s mounting bracket

T5A06 - How much voltage does a mobile transceiver usually require? A. About 12 volts B. About 30 volts C. About 120 volts D. About 240 volts

T6D05 - What type of circuit controls the amount of voltage from a power supply? A. Regulator B. Oscillator C. Filter D. Phase inverter

T7B09 - What could be happening if another operator reports a variable high-pitched whine on the audio from your mobile transmitter? A. Your microphone is picking up noise from an open window B. You have the volume on your receiver set too high C. You need to adjust your squelch control D. Noise on the vehicle’s electrical system is being transmitted along with your speech audio

Batteries Create electrical energy through a chemical reaction. Primary cell. Chemical reaction is not reversible. Cannot be recharged. Secondary cell. Chemical reaction is reversible. Can be recharged.

Batteries Cell voltage depends on chemicals used. Capacity rated in Ampere-hours (AH) or milliampere hours (mAH). 500 mAH battery will provide: 500 mA for 1 hour. 50 mA for 10 hours. 25 mA for 20 hours. 5 mA for 100 hours. etc.

Batteries Lead-Acid. Secondary cell. Approximately 2.12 Volts per cell. “12V” battery = 6 cells in series. Open-Circuit at full charge: 12.6 V to 12.8 V Open-circuit at full discharge: 11.8 V to 12.0 V Loaded at full discharge: 10.5 V Float Charge: 13.8 V Daily Charge: 14.2 V to 14.5 V

Batteries Lead-Acid. If overcharged will release hydrogen gas. Remember the Hindenberg! ALWAYS use in well-ventilated area! Gassing threshold ~14.4 V.

Batteries Gel-Cell. a.k.a. – Sealed lead-acid (SLA). Electrolyte is in a gel form rather then liquid. Sealed so does not vent hydrogen gas. Avoid over charging to prevent build up of internal pressure.

Other Types of Batteries Chemistry Cell Voltage Type Carbon-Zinc (obsolete) 1.5V Disposable Alkaline Disposable* Nickel-Cadmium (NiCad) 1.2V Rechargeable Nickel-Metal-Hydride (NiMH) Lithium Ion (LI-Ion) 3.6V

Battery Charging Some batteries can be recharged, some cannot. Use the proper charger for the battery being charged. Batteries will wear out over time. Best if batteries are maintained fully charged. Over-charging will cause heating and could damage the battery.

Handheld Transceiver Batteries Battery packs – packages of several individual rechargeable batteries connected together. NiCd (nickel-cadmium). NiMH (nickel-metal hydride). Li-ion (lithium-ion). For emergencies, have a battery pack that can use disposable batteries (usually AA size).

T6A10 - What is the nominal voltage of a fully charged nickel-cadmium cell? A. 1.0 volts B. 1.2 volts C. 1.5 volts D. 2.2 volts

T6A11 - Which battery type is not rechargeable? A. Nickel-cadmium B. Carbon-zinc C. Lead-acid D. Lithium-ion

T0A08 - What is one way to recharge a 12-volt lead-acid station battery if the commercial power is out? A. Cool the battery in ice for several hours B. Add acid to the battery C. Connect the battery to a car’s battery and run the engine D. All of these choices are correct

T0A09 - What kind of hazard is presented by a conventional 12-volt storage battery? A. It emits ozone which can be harmful to the atmosphere B. Shock hazard due to high voltage C. Explosive gas can collect if not properly vented D. All of these choices are correct

T0A10 - What can happen if a lead-acid storage battery is charged or discharged too quickly? A. The battery could overheat and give off flammable gas or explode B. The voltage can become reversed C. The “memory effect” will reduce the capacity of the battery D. All of these choices are correct

Radio Frequency Interference (RFI) Radio frequency signals (RF) causing interference with the proper operation of an electronic device. Your transmitted signal can interfere with electronic devices, even if it is operating properly. Radio frequency signals generated by electrical devices can interfere with your receiver.

Radio Frequency Interference (RFI) Filters. Used to prevent interfering signals from entering a piece of equipment. High-Pass -- Passes frequencies above a frequency. Low-Pass -- Passes frequencies below a frequency. Band-Pass -- Passes frequencies within a frequency range. Band-Reject -- Passes frequencies outside of a frequency range.

Radio Frequency Interference (RFI) RF choke. a.k.a. – Common-mode choke. a.k.a. – Ferrite choke. Special type magnetic material (ferrite) placed around a conductor or cable. The “lump” in computer cables. Prevents RF from entering or leaving a piece of electronic equipment via the cable.

Radio Frequency Interference (RFI) Ferrite choke.

Types of RFI Direct detection. The presence of a strong RF signal can interference with an electronic device even if the transmitter is operating properly. Often caused by the device acting as a receiver even when it is not designed to. Semiconductors in the device can act as diode detectors. This is called direct detection.

Types of RFI Direct detection. Telephones. Stereos. Direct detection is most common type of RFI. Low-pass filter at telephone wall jack. Ferrite choke on telephone cord. Stereos. Touch-activated lamps. Electronic doorbells.

Types of RFI Overload. Very strong off-frequency signals can overwhelm the input stages of a receiver. Interfering signal may be heard regardless of frequency (channel) receiver is tuned to. Problem lies within the receiver. Add filters to receiver input. e.g. – Add band-reject (notch) filter to prevent a 2-meter signal from interfering with broadcast TV. Adding filters to transmitter will not help.

Types of RFI Harmonics & Spurious Emissions. All transmitted signals contain harmonics and other spurious emissions (spurs). Goal is to reduce strength of harmonics & spurs as much as possible. Good transmitter design. Proper operation.

Types of RFI Harmonics & Spurious Emissions. Problem lies within the transmitter. Install low-pass filter or band-pass filter between transmitter and antenna to reduce harmonics. Filtering may not reduce strength of spurious emissions (non-harmonic) if close to transmitter frequency. Adding filters to receiver input will not help.

Types of RFI Cable TV Interference Usually the result of broken shielding somewhere in the cable. Loose connections. Broken connections. Corroded connections. Usually solved by proper cable maintenance by cable supplier.

Types of RFI Noise Sources. Most interference to amateur radio receivers is not from transmitters, but from “unintentional radiators”. Electrical arcs (motors, thermostats, electric fences, neon signs, etc.). Power lines. Motor vehicle ignitions or alternators. Switching power supplies. Computers, networks, and TV sets.

Types of RFI Intermodulation. Two signals combine (mix) to produce an interfering signal. Find circuit where mixing is occurring. Add filter(s) to eliminate one or both of the signals being mixed.

Dealing with RFI Make sure you operate your equipment properly. Eliminate interference in your own home first.

Dealing with RFI Take interference complaints seriously. Make sure that you’re really not the cause. Demonstrate that you don’t interfere within your own home. Offer to help eliminate the RFI, even if you are not at fault. Consult ARRL RFI Resources for help and assistance.

What the Rules Say RFI from and to unlicensed devices is the responsibility of the users of such devices. Bottom line – If your station is operating properly, you are protected against interference complaints. BUT – Be a good neighbor because they may (probably) not be familiar with Part 15 rules and regulations.

T4A04 - Where must a filter be installed to reduce harmonic emissions? A. Between the transmitter and the antenna B. Between the receiver and the transmitter C. At the station power supply D. At the microphone

T4A05 - What type of filter should be connected to a TV receiver as the first step in trying to prevent RF overload from a nearby 2 meter transmitter? A. Low-pass filter B. High-pass filter C. Band-pass filter D. Band-reject filter

T4A09 - Which would you use to reduce RF current flowing on the shield of an audio cable? A. Band-pass filter B. Low-pass filter C. Preamplifier D. Ferrite choke

T7B04 - What is the most likely cause of interference to a non-cordless telephone from a nearby transmitter? A. Harmonics from the transmitter B. The telephone is inadvertently acting as a radio receiver C. Poor station grounding D. Improper transmitter adjustment

T7B05 - What is a logical first step when attempting to cure a radio frequency interference problem in a nearby telephone? A. Install a low-pass filter at the transmitter B. Install a high-pass filter at the transmitter C. Install an RF filter at the telephone D. Improve station grounding

T7B06 - What should you do first if someone tells you that your station’s transmissions are interfering with their radio or TV reception? A. Make sure that your station is functioning properly and that it does not cause interference to your own television B. Immediately turn off your transmitter and contact the nearest FCC office for assistance C. Tell them that your license gives you the right to transmit and nothing can be done to reduce the interference D. Continue operating normally because your equipment cannot possibly cause any interference

T7B07 - Which of the following may be useful in correcting a radio frequency interference problem? A. Snap-on ferrite chokes B. Low-pass and high-pass filters C. Band-reject and band-pass filters D. All of these choices are correct

T7B08 - What should you do if a “Part 15” device in your neighbor’s home is causing harmful interference to your amateur station? A. Work with you neighbor to identify the offending device B. Politely inform your neighbor about the rules that require him to stop using the device if it causes interference C. Check your station and make sure it meets the standards of good amateur practice D. All of these choices are correct

Electrical Grounding Make sure your home is “up to code.” Most ham equipment does not require special wiring or circuits. Use 3-wire power cords. Use circuit breakers, circuit breaker outlets, or Ground Fault Interrupter (GFI) circuit breakers. Use proper fuse or circuit breaker size. Don’t overload single outlets.

RF Grounding Amateur radio stations require a separate “RF” ground. Lack of a proper RF ground can result in: RF burns when touching equipment while transmitting. RF feedback resulting in distorted audio on transmitted signal. Erratic operation of computer equipment.

RF Grounding All equipment should be connected to a common ground. Ground should be as short as possible. Use wide, flat copper strap or braid.

Lightning Protection Install a separate ground rod by each leg of your tower. Do NOT run ground rods through concrete base. Ground rods should be bonded to the tower leg & to each other. Connect to station ground.

T7B11 - What is a symptom of RF feedback in a transmitter or transceiver? A. Excessive SWR at the antenna connection B. The transmitter will not stay on the desired frequency C. Reports of garbled, distorted, or unintelligible transmissions D. Frequent blowing of power supply fuses

T4A08 - What type of conductor is best to use for RF grounding? A. Round stranded wire B. Round copper-clad steel wire C. Twisted-pair cable D. Flat strap

Questions?

Technician License Class Next Session Chapter 7 Licensing Regulations Chapter 8 Operating Regulations