General Licensing Class “G6”

1. General Licensing Class“G6” Presented by the Opp Amateur Radio Club Opp, AL Wednesday, October 29, 2014

2. General Class Element 3 Course Presentation • ELEMENT 3 SUB-ELEMENTS G1 – Commission’s Rules G2 – Operating Procedures G3 – Radio Wave Propagation G4 – Amateur Radio Practices G5 – Electrical Principles G6 – Circuit Components G7 – Practical Circuits G8 – Signals and Emissions G9 – Antennas G0 – Electrical and RF Safety

3. G6…Circuit Components G6A • Resistors • If the temperature of a carbon resistor is increased, the resistance will change depending on the resistor's temperature coefficient rating. Example of Carbon Resistors Example of a wire-wound resistor • The main disadvantage of using a conventional wire-wound resistor in a resonant circuit is the resistor's inductance could detune the circuit.

4. G6…Circuit ComponentsG6A Resistors (cont) A thermistor is a device having a controlled change in resistance with temperature variations. Example of a Thermistor • Thermistors are commonly used in modern digital thermostats and to monitor the temperature of battery packs while charging.

5. G6…Circuit Components G6A Electrolytic Capacitors An Electrolytic type of capacitor is often used in power-supply circuits to filter the rectified AC. An advantage of an electrolytic capacitor is the high capacitance for given volume. Examples of Electrolytic capacitor Example of Ceramic Disk Capacitors • Ceramic Disk Capacitors • The primary advantage of ceramic capacitors is the comparatively low cost. • Notes concerning different types of Capacitors. • One effect of lead inductance in a capacitor used at VHF and above is effective capacitance may be reduced. • The common name for a capacitor connected across a transformer secondary that is used to absorb transient voltage spikes is Suppressor capacitor.

6. G6…Circuit Components G6A Notes on Inductors The advantages of using a ferrite core with a toroidal inductor are: Large values of inductance may be obtained The magnetic properties of the core may be optimized for a specific range of frequencies Most of the magnetic field is contained in the core [All of these choices are correct] Two solenoid inductors should be placed with their winding axes at right angles to each another to minimize their mutual inductance. It might be important to minimize the mutual inductance between two inductors to reduce or eliminate unwanted coupling. An effect of inter-turn capacitance in an inductor is the inductor may become self resonant at some frequencies. The common name for an inductor used to help smooth the DC output from the rectifier in a conventional power supply is a Filter choke. • While a capacitor opposes changes in voltage, an inductor opposes changes in current.

7. G6A Questions The following questions are taken directly from the Element 3 General Question Pool. These are the same questions that will appear on your test.

8. G6A01 What will happen to the resistance if the temperature of a carbon resistor is increased? • It will increase by 20% for every 10 degrees centigrade • It will stay the same • It will change depending on the resistor's temperature coefficient rating • It will become time dependent

9. G6A02 What type of capacitor is often used in power-supply circuits to filter the rectified AC? • Disc ceramic • Vacuum variable • Mica • Electrolytic

10. G6A03 Which of the following is the primary advantage of ceramic capacitors? • Tight tolerance • High stability • High capacitance for given volume • Comparatively low cost

11. G6A04 Which of the following is an advantage of an electrolytic capacitor? • Tight tolerance • Non-polarized • High capacitance for given volume • Inexpensive RF capacitor

12. G6A05 Which of the following is one effect of lead inductance in a capacitor used at VHF and above? • Effective capacitance may be reduced • Voltage rating may be reduced • ESR may be reduced • The polarity of the capacitor might become reversed

13. G6A06 What is the main disadvantage of using a conventional wire-wound resistor in a resonant circuit? • The resistor's tolerance value would not be adequate for such a circuit • The resistor's inductance could detune the circuit • The resistor could overheat • The resistor's internal capacitance would detune the circuit

14. G6A07 What is an advantage of using a ferrite core with a toroidal inductor? • Large values of inductance may be obtained • The magnetic properties of the core may be optimized for a specific range of frequencies • Most of the magnetic field is contained in the core • All of these choices are correct

15. G6A08 How should two solenoid inductors be placed so as to minimize their mutual inductance? • In line with their winding axis • With their winding axes parallel to each other • With their winding axes at right angles to each another • Within the same shielded enclosure

16. G6A09 Why might it be important to minimize the mutual inductance between two inductors? • To increase the energy transfer between both circuits • To reduce or eliminate unwanted coupling • To reduce conducted emissions • To increase the self-resonant frequency of both inductors

17. G6A10 What is an effect of inter-turn capacitance in an inductor? • The magnetic field may become inverted • The inductor may become self resonant at some frequencies • The permeability will increase • The voltage rating may be exceeded

18. G6A11 What is the common name for a capacitor connected across a transformer secondary that is used to absorb transient voltage spikes? • Clipper capacitor • Trimmer capacitor • Feedback capacitor • Suppressor capacitor

19. G6A12 What is the common name for an inductor used to help smooth the DC output from the rectifier in a conventional power supply? • Back EMF choke • Repulsion coil • Charging inductor • Filter choke

20. G6A13 What type of component is a thermistor? • A resistor that is resistant to changes in value with temperature variations • A device having a controlled change in resistance with temperature variations • A special type of transistor for use at very cold temperatures • A capacitor that changes value with temperature

21. G6…Circuit Components G6B Rectifiers and Solid state diodes The peak-inverse-voltage rating of a rectifier is the maximum voltage the rectifier will handle in the non-conducting direction. The two major ratings that must not be exceeded for silicon-diode rectifiers are Peak Inverse Voltage and Average Forward Current. When two or more diodes are connected in parallel to increase current handling capacity, the purpose of the resistor connected in series with each diode is to ensure that one diode doesn't carry most of the current. The approximate junction threshold voltage of a germanium diode is 0.3 volts. The approximate junction threshold voltage of a silicon diode is 0.7 volts. An advantage of using a Schottky diode in an RF switching circuit as compared to a standard silicon diode is lower capacitance. Q : What is a Rectifier? A : A rectifier is an electrical device that converts alternating current to direct current, a process known as rectification. Rectifiers are used as components of power supplies and as detectors of radio signals. Rectifiers may be made of solid state diodes, vacuum tube diodes, mercury arc valves, and other components.

22. G6…Circuit Components G6B Notes about Transistors: The stable operating points for a bipolar transistor that is used as a switch in a logic circuit are the transistor’s saturation and cut-off regions. It is often necessary to insulate the case of a large power transistor to avoid shorting the collector or drain voltage to ground. In the construction of a MOSFET the gate is separated from the channel with a thin insulating layer. A Field Effect Transistor (FET) is a solid state device and is most like a vacuum tube in its general characteristics. Q : What is a Transistor? A : A transistor is a semiconductor device, commonly used as an amplifier or an electrically controlled switch. Examples of different transistors

23. G6…Circuit ComponentsG6B Notes about Vacuum Tubes: The Control Grid element of a triode vacuum tube is used to regulate the flow of electrons between cathode and plate. The primary purpose of a screen grid in a vacuum tube is to reduce grid‑to‑plate capacitance. Q : What is a Vacuum Tube? A : A vacuum tube is a device used to amplify, switch, otherwise modify, or create an electrical signal by controlling the movement of electrons in a low-pressure space, often not tubular in form Example of a Vacuum Tube

24. G6…Circuit Components G6B Important notes about Batteries: An advantage of the low internal resistance of Nickel Cadmium batteries is high discharge current. The minimum allowable discharge voltage for maximum life of a standard 12 volt lead acid battery is 10.5 volts. It is never acceptable to recharge a carbon-zinc primary cell. A Nickel Metal Hydride is a rechargeable battery. Types of Batteries : • Lead Acid – Car Batteries – UPS batteries • Nickel Cadmium – Older type of rechargeable batteries. • Nickel Metal Hydride – Generally found in high power devices like laptop computers or digital cameras. Rechargable • Carbon-Zinc – Most disposable batteries

25. G6B Questions The following questions are taken directly from the Element 3 General Question Pool. These are the same questions that will appear on your test.

26. G6B01 What is the peak-inverse-voltage rating of a rectifier? • The maximum voltage the rectifier will handle in the conducting direction • 1.4 times the AC frequency • The maximum voltage the rectifier will handle in the non-conducting direction • 2.8 times the AC frequency

27. G6B02 What are the two major ratings that must not be exceeded for silicon-diode rectifiers? • Peak inverse voltage; average forward current • Average power; average voltage • Capacitive reactance; avalanche voltage • Peak load impedance; peak voltage

28. G6B03 What is the approximate junction threshold voltage of a germanium diode? • 0.1 volt • 0.3 volts • 0.7 volts • 1.0 volts

29. G6B04 When two or more diodes are connected in parallel to increase current handling capacity, what is the purpose of the resistor connected in series with each diode? • The resistors ensure the thermal stability of the power supply • The resistors regulate the power supply output voltage • The resistors ensure that one diode doesn't carry most of the current • The resistors act as swamping resistors in the circuit

30. G6B05 What is the approximate junction threshold voltage of a silicon diode? • 0.1 volt • 0.3 volts • 0.7 volts • 1.0 volts

31. G6B06 Which of the following is an advantage of using a Schottky diode in an RF switching circuit as compared to a standard silicon diode? • Lower capacitance • Lower inductance • Longer switching times • Higher breakdown voltage

32. G6B07 What are the stable operating points for a bipolar transistor that is used as a switch in a logic circuit? • Its saturation and cut-off regions • Its active region (between the cut-off and saturation regions) • Between its peak and valley current points • Between its enhancement and deletion modes

33. G6B08 Why is it often necessary to insulate the case of a large power transistor? • To increase the beta of the transistor • To improve the power dissipation capability • To reduce stray capacitance • To avoid shorting the collector or drain voltage to ground

34. G6B09 Which of the following describes the construction of a MOSFET? • The gate is formed by a back-biased junction • The gate is separated from the channel with a thin insulating layer • The source is separated from the drain by a thin insulating later • The source is formed by depositing metal on silicon

35. G6B10 Which element of a triode vacuum tube is used to regulate the flow of electrons between cathode and plate? • Control grid • Heater • Screen Grid • Suppressor grid

36. G6B11 Which of the following solid state devices is most like a vacuum tube in its general characteristics? • A bipolar transistor • An FET • A tunnel diode • A varistor

37. G6B12 What is the primary purpose of a screen grid in a vacuum tube? • To reduce grid-to-plate capacitance • To increase efficiency • To increase the high frequency response • To decrease plate resistance

38. G6B13 What is an advantage of the low internal resistance of Nickel Cadmium batteries? • Long life • High discharge current • High voltage • Rapid recharge

39. G6B14 What is the minimum allowable discharge voltage for maximum life of a standard 12 volt lead acid battery? • 6 volts • 8.5 volts • 10.5 volts • 12 volts

40. G6B15 When is it acceptable to recharge a carbon-zinc primary cell? • As long as the voltage has not been allowed to drop below 1.0 volt • When the cell is kept warm during the recharging period • When a constant current charger is used • Never

41. G6B16 Which of the following is a rechargeable battery? • Carbon-zinc • Silver oxide • Nickel Metal Hydride • Mercury

42. G6…Circuit ComponentsG6C Notes about Intergrated Circuits: Linear voltage regulator is an analog integrated circuit. An operational amplifier is an Analog type of integrated circuit. CMOS is the most commonly used digital logic family of integrated circuits. An advantage of CMOS Logic integrated circuits compared to TTL logic circuits is the low power consumption. Q : What is a Integrated Circuit? A : An integrated circuit (also known as IC, microcircuit, microchip, silicon chip, or chip) is a miniaturized electronic circuit (consisting mainly of semiconductor devices, as well as passive components) that has been manufactured in the surface of a thin substrate of semiconductor material.

43. G6…Circuit ComponentsG6C • Microprocessors • A microprocessor is a miniature computer on a single integrated circuit chip • Memory • Read Only Memory (ROM) • When memory is characterized as “non-volatile” the stored information is maintained even if power is removed. • I/O devices • A Computer and transceiver are two devices in an amateur radio station that might be connected using a USB interface. • Microwave IC’s (MMIC’s ) • Monolithic Microwave Integrated Circuit (MMIC) • Display devices • One disadvantage of an incandescent indicator compared to a LED is the high pwr consumption. • An LED is Forward Biased when emitting light. • A liquid crystal display requires ambient or back lighting.

44. G6C Questions The following questions are taken directly from the Element 3 General Question Pool. These are the same questions that will appear on your test.

45. G6C01 Which of the following is most often provided as an analog integrated circuit? • NAND Gate • Gallium Arsenide UHF Receiver “front end” Amplifier • Frequency Counter • Linear voltage regulator

46. G6C02 Which of the following is the most commonly used digital logic family of integrated circuits? • RTL • TTL • CMOS • PMOS

47. G6C03 Which of the following is an advantage of CMOS Logic integrated circuits compared to TTL logic circuits? • Low power consumption • High power handling capability • Better suited for RF amplification • Better suited for power supply regulation

48. G6C04 What is meant by the term ROM? • Resistor Operated Memory • Read Only Memory • Random Operational Memory • Resistant to Overload Memory

49. G6C05 What is meant when memory is characterized as “non-volatile”? • It is resistant to radiation damage • It is resistant to high temperatures • The stored information is maintained even if power is removed • The stored information cannot be changed once written

50. G6C06 Which type of integrated circuit is an operational amplifier? • Digital • MMIC • Programmable • Analog