Amateur Radio License - Stanford University
Amateur RadioLicenseSafety
Test Format 35 questions from a pool of 300 You need to get 26 right (74%) Multiple choice Calculators allowed (but you don’t really need one) You have to take this on-line
Test No Stanford test due toCovid Several online sites hamstudy.org has a list You schedule ityourself Not as much fun
Free Radio For Stanford affiliates Baofeng UV5R Programmed with all thelocal repeaters
Todays Topics Digital Radio Safety: Chapter 9 Electrical Safety RF Exposure Mechanical Safety
Digital Radio
Digital Radio Repeaters that use the internet (VoIP) DStar (ICom, Kenwood) C4FM, Wires (Yaesu) DMR — Digital Mobile Radio(Lots of companies)
Echo Link and oIPRepeater HandheldRadio Linked repeaters using “Voice over IP” (the internet) Type in access code, address of the repeater to link to usingDTMF tones (same tones a phone uses) Acts like one big repeater, even though far apart IRLP is RF on both ends, Echo Link can use a computer
Digital Mobil Radio lFMHandheldRadioRepeaterInternetServerRepeater HandheldRadioDigitalFMRepeater HandheldRadio
DMR Each user has an ID Your repeater tells the network you are there You can connect to an individual user directly (rare) You can connect to a “talk group” (most common)
HandheldRadioRepeaterInternetRepeater TAC 310ServerTAC 310RepeaterRepeaterTAC 310 TAC 310 is a talk group I tell my repeater I want to access TAC 310 by selecting iton the radio, and hitting the PTT button momentarily Other people do the same for their repeaters. We all hear all the traffic on the talk group, all over theworld.
DMR Lots of talk groups, can be based on geography,interest, or organization Your local repeater may be transmitting several talkgroups at the same time, but you’ll only hear theone you selected. You can also listen to everything You can send text to specific users, as well as SMSmessages to/from phones
DMR Radios Looks just like the UV-5R Radioddity DMR internals 65 A real challenge to program Don’t get the DM-5R! It costsabout the same, but doesn’twork on DMR networks
DMR HotspotsZumspot Raspberry Pi-Zero and RF daughtercard Acts like a DMR repeater(100 mW) It connects to the DMR servers overWiFi Also does DStar, C4FM, P25 110 Non-trivial to program
Zumspot
QRZ
Electrical Hazards
Electrical Hazards Shocks Burns Even smallcurrents cancause problems
Electrical Safety Avoid contact Most modern equipment is low voltage, low hazard Old equipment (tube amps for example) can behigh voltage, quite hazardous
Mitigating Electrical Hazards If power is required: Remove jewelry. Avoid unintentional touching of circuitry. Never bypass safety interlocks. Capacitors hold a charge even when power is off. Storage batteries are dangerous when shorted
Mitigating Electrical Hazards Turn off power when working inside equipment! Make sure equipment is properly grounded andcircuit protected! Keep one hand in pocket when working aroundhigh voltage circuits.
Responding to ElectricalInjury REMOVE POWER! Have ON/OFF switches and circuit breakersclearly marked. Call for help. Learn CPR and first aid.
Lightning Safety Antennas are not struck any more frequently thantrees or tall structures. Ground all antennas. Use lightning arrestors. Disconnect antenna cables and power cords duringstorms. Disconnect telephone lines from computer modems.
What health hazard is presented bycurrent flowing through the body?(T0A02)A. By heating tissueB. It disrupts the electrical functions of cellsC. It causes involuntary muscle contractionsD. All of these choices are correct
What health hazard is presented bycurrent flowing through the body?(T0A02)A. By heating tissueB. It disrupts the electrical functions of cellsC. It causes involuntary muscle contractionsD. All of these choices are correct
In the US, what is connected to the greenwire in a three-wire electrical AC plug?(T0A03)A. NeutralB. HotC. Safety groundD. The white wire
In the US, what is connected to the greenwire in a three-wire electrical AC plug?(T0A03)A. NeutralB. HotC. Safety groundD. The white wireWhite is neutral, black or red is hot
Which of these precautions should be takenwhen installing devices for lightning protectionin a coaxial cable feedline? (T0A07)A. Include a parallel bypass switch for each protector sothat it can be switched out of the circuit when runninghigh powerB. Include a series switch in the ground line of eachprotector to prevent RF overload from inadvertentlydamaging the protectorC. Keep the ground wires from each protector separate andconnected to station groundD. Ground all of the protectors to a common plate which isin turn connected to an external ground
Which of these precautions should be takenwhen installing devices for lightning protectionin a coaxial cable feedline? (T0A07)A. Include a parallel bypass switch for each protector sothat it can be switched out of the circuit when runninghigh powerB. Include a series switch in the ground line of eachprotector to prevent RF overload from inadvertentlydamaging the protectorC. Keep the ground wires from each protector separate andconnected to station groundD. Ground all of the protectors to a common plate whichis in turn connected to an external ground
What kind of hazard might exist in a powersupply when it is turned off anddisconnected? T0A11A. Static electricity could damage the groundingsystemB. Circulating currents inside the transformer mightcause damageC. The fuse might blow if you remove the coverD. You might receive a shock from the charge storedin large capacitors
What kind of hazard might exist in a powersupply when it is turned off anddisconnected? T0A11A. Static electricity could damage the groundingsystemB. Circulating currents inside the transformer mightcause damageC. The fuse might blow if you remove the coverD. You might receive a shock from the chargestored in large capacitors
Which of the following establishesgrounding requirements for an amateurradio tower or antenna? (T0B11)A. FCC Part 97 RulesB. Local electrical codesC. FAA tower lighting regulationsD. Underwriters Laboratories’ recommendedpractices
Which of the following establishesgrounding requirements for an amateurradio tower or antenna? (T0B11)A. FCC Part 97 RulesB. Local electrical codesC. FAA tower lighting regulationsD. Underwriters Laboratories’ recommendedpractices
RF Exposure
RF Exposure Exposure to high levels of RF can cause problems. If precautions are taken, RF exposure is minimaland not dangerous. RF energy can heat body tissues. Heating depends on the RF intensity andfrequency.
RF Power Density Actual transmitter power. Higher power, higher risk.Antenna gain and proximity. Beam antennas focus available energy. Physical proximity or standing in the beam increasesrisk.Mode duty cycle. More time at high power level, higher risk.
Antenna Proximity Controlled Environment: You know where people are standing in relation to yourantenna and you can do something about it. More power is allowed because you can makeadjustments if needed.Uncontrolled Environment: You have no idea, or have no control of people nearyour antenna. Less power is allowed because you have to assumethe worse case scenario.
RF Exposure and Frequency When body parts act like antennas, those partsabsorb RF energy at certain frequencies(wavelengths) more efficiently and increase risk. RF exposure risk varies with frequency. More caution is dictated at some frequencies morethan other frequencies.
RF Exposure and Frequency
Mode DutyCycle Higher duty cycle,greater RF exposure
RF Exposure Evaluation All fixed stations must perform an exposure evaluation.Several methods are available to do this. At lower power levels, no evaluation is required. Varieswith frequency – example: below 50 W at VHF. Relocating antennas is one way to reduce RF exposure Also, regardless of the exposure evaluation results,make sure that people cannot come into contact withyour antennas – RF burns are painful
Evaluation ThresholdsBand(m)Power (W)80, lower500405002022510502501.25500.7700.232000.13, higher250
Which of the following frequencies has thelowest Maximum Permissible Exposurelimit? (T0C02)A. 3.5 MHzB. 50 MHzC. 440 MHzD. 1296 MHz
Which of the following frequencies has thelowest Maximum Permissible Exposurelimit? (T0C02)A. 3.5 MHzB. 50 MHzC. 440 MHzD. 1296 MHz
What is the maximum power level that an amateurradio station may use at VHF frequencies beforean RF exposure evaluation is required? (T0C03)A. 1500 watts PEP transmitter outputB. 1 watt forward powerC. 50 watts PEP at the antennaD. 50 watts PEP reflected power
What is the maximum power level that an amateurradio station may use at VHF frequencies beforean RF exposure evaluation is required? (T0C03)A. 1500 watts PEP transmitter outputB. 1 watt forward powerC. 50 watts PEP at the antennaD. 50 watts PEP reflected power
What factors affect the RF exposure ofpeople near an amateur radio antenna?(T0C04)A. Frequency and power level of the RF fieldB. Distance from the antenna to the personC. Radiation pattern of the antennaD. All of these choices are correct
What factors affect the RF exposure ofpeople near an amateur radio antenna?(T0C04)A. Frequency and power level of the RF fieldB. Distance from the antenna to the personC. Radiation pattern of the antennaD. All of these choices are correct
Why do exposure limits varywith frequency? (T0C05)A. Lower frequency RF fields have more energy thanhigher frequency fieldsB. Lower frequency RF fields do not penetrate thehuman bodyC. Higher frequency RF fields are transient in natureD. The human body absorbs more RF energy atsome frequencies than at others
Why do exposure limits varywith frequency? (T0C05)A. Lower frequency RF fields have more energy thanhigher frequency fieldsB. Lower frequency RF fields do not penetrate thehuman bodyC. Higher frequency RF fields are transient in natureD. The human body absorbs more RF energy atsome frequencies than at others
Which of the following is an acceptable methodto determine that your station complies withFCC RF exposure regulations? (T0C06)A. By calculation based on FCC OET Bulletin 65B. By calculation based on computer modelingC. By measurement of field strength using calibratedequipmentD. All of these choices are correct
Which of the following is an acceptable methodto determine that your station complies withFCC RF exposure regulations? (T0C06)A. By calculation based on FCC OET Bulletin 65B. By calculation based on computer modelingC. By measurement of field strength using calibratedequipmentD. All of these choices are correct
Why is duty cycle one of the factors usedto determine safe RF radiation exposurelevels? (T0C10)A. It affects the average exposure of people toradiationB. It affects the peak exposure of people to radiationC. It takes into account the antenna feedline lossD. It takes into account the thermal effects of the finalamplifier
Why is duty cycle one of the factors usedto determine safe RF radiation exposurelevels? (T0C10)A. It affects the average exposure of people toradiationB. It affects the peak exposure of people to radiationC. It takes into account the antenna feedline lossD. It takes into account the thermal effects of the finalamplifier
Physical Safety
Driving Amateur radio exempt from CA cell phone law Doesn’t cover two way radios People still get ticketsMake sure equipment is secure, that you canoperate it safely
Antenna Towers Power lines and trees Lightning and grounding Climbing towers
Tower Installation Clear of trees and power lines. If it falls it won’t hit anyone or cross power linesNo closer than 10 feet from power line if the towerfalls over. Towers should use proper grounding techniques.
Tower Work Proper clothing, hard hat and eye protection. Climbing harness. Gin pole: used for lifting tower sections andantennas. Don’t climb a crank-up tower supported by itscable. Don’t work alone.
Under what circumstances is it safe toclimb a tower without a helper orobserver? (T0B03)A. When no electrical work is being performedB. When no mechanical work is being performedC. When the work being done is not more than 20feet above groundD. Never
Under what circumstances is it safe toclimb a tower without a helper orobserver? (T0B03)A. When no electrical work is being performedB. When no mechanical work is being performedC. When the work being done is not more than 20feet above groundD. Never
Which of the following is an importantsafety precaution to observe when puttingup an antenna tower? (T0B04)A. Wear a ground strap connected to your wrist at alltimesB. Insulate the base of the tower to avoid lightningstrikesC. Look for and stay clear of any overhead electricalwiresD. All of these choices are correct
Which of the following is an importantsafety precaution to observe when puttingup an antenna tower? (T0B04)A. Wear a ground strap connected to your wrist at alltimesB. Insulate the base of the tower to avoid lightningstrikesC. Look for and stay clear of any overheadelectrical wiresD. All of these choices are correct
What is the minimum safe distance from apower line to allow when installing anantenna? (T0B06)A. Half the width of your propertyB. The height of the power line above groundC. ½ wavelength at the operating frequencyD. So that if the antenna falls unexpectedly, no partof it can come closer than 10 feet to the powerlines
What is the minimum safe distance from apower line to allow when installing anantenna? (T0B06)A. Half the width of your propertyB. The height of the power line above groundC. ½ wavelength at the operating frequencyD. So that if the antenna falls unexpectedly, nopart of it can come closer than 10 feet to thepower lines
What is considered to be a propergrounding method for a tower? (T0B08)A. A single four-foot ground rod, driven into theground no more than 12 inches from the baseB. A ferrite-core RF choke connected between thetower and groundC. Separate eight-foot long ground rods for eachtower leg, bonded to the tower and each otherD. A connection between the tower base and a coldwater pipe
What is considered to be a propergrounding method for a tower? (T0B08)A. A single four-foot ground rod, driven into theground no more than 12 inches from the baseB. A ferrite-core RF choke connected between thetower and groundC. Separate eight-foot long ground rods for eachtower leg, bonded to the tower and each otherD. A connection between the tower base and a coldwater pipe
Why should you avoid attaching anantenna to a utility pole? (T0B09)A. The antenna will not work properly because ofinduced voltagesB. The utility company will charge you an extramonthly feeC. The antenna could contact high-voltage powerwiresD. All of these choices are correct
Why should you avoid attaching anantenna to a utility pole? (T0B09)A. The antenna will not work properly because ofinduced voltagesB. The utility company will charge you an extramonthly feeC. The antenna could contact high-voltage powerwiresD. All of these choices are correct
That’s It! Good luck with the exam!
Radio Repeater Repeater Internet Server TAC 310 TAC 310 TAC 310 TAC 310 is a talk group I tell my repeater I want to access TAC 310 by selecting it on the radio, and hitting the PTT button momentarily Other pe
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Radio in the US only to 1936—but contains 184 pages. The 1800s—Prehistory The last few years of the 19th century set the stage for rapid development of commercial radio and established the foundations of Amateur Radio. There were numerous early contribu-tors to the radio art, such as the great Oersted, Ampere, Faraday, Henry, and others .
