1 / 66

General Licensing Class “G7”

General Licensing Class “G7”. Presented by the Your Organization Goes here Your date here. 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

deanna
Télécharger la présentation

General Licensing Class “G7”

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. General Licensing Class“G7” Presented by the Your Organization Goes here Your date here

  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 2

  3. G7 … Practical Circuits G7A • Power Supplies • A power-supply bleeder resistor discharges the filter capacitors providing a safety feature. • Capacitors and inductors are used in a power-supply filter network.

  4. G7 … Practical Circuits G7A • Power Supplies (cont) • An advantage of a switched-mode power supply as compared to a linear power supply is high frequency operation allows the use of smaller components. Interior view of a switched-mode power supply: A - bridge rectifierB - Input filter capacitorsC - TransformerD - output filter coilE - output filter capacitors

  5. G7 … Practical Circuits G7A • Power Supplies (cont) • A 180 degree portion of the AC cycle is converted to DC by a half-wave rectifier.

  6. G7 … Practical Circuits G7A • Power Supplies (cont) (Repeat) • A 180 degree portion of the AC cycle is converted to DC by a half-wave rectifier.

  7. G7 … Practical Circuits G7A • Power Supplies (cont) • A 360 degree portion of the AC cycle is converted to DC by a full-wave rectifier. • The output waveform of an unfiltered full-wave rectifier connected to a resistive load is a series of DC pulses at twice the frequency of the AC input.

  8. G7 … Practical Circuits G7A • Power Supplies (cont) (Repeat) • A 360 degree portion of the AC cycle is converted to DC by a full-wave rectifier. • The output waveform of an unfiltered full-wave rectifier connected to a resistive load is a series of DC pulses at twice the frequency of the AC input.

  9. G7 … Practical Circuits G7A • Power Supplies (cont) • The minimum peak-inverse-voltage rating of the rectifier in a full-wave power supply should be double the normal peak output voltage of the power supply. • The approximate minimum peak-inverse-voltage rating of the rectifier in a half-wave power supply should be two times the normal peak output voltage of the power supply. • A desirable characteristic for capacitors used to filter the DC output of a switching power supply is low equivalent series resistance.

  10. G7 … Practical Circuits G7A • Transmitters • A Balanced modulator circuit is used to combine signals from the carrier oscillator and speech amplifier and send the result to the filter in a typical single‑sideband phone transmitter. • An advantage of a crystal controlled transmitter is a Stable output frequency.

  11. G7 … Practical Circuits G7A • Receivers • A Mixer circuit is used to process signals from the RF amplifier and local oscillator and send the result to the IF filter in a super heterodyne receiver.

  12. G7 … Practical Circuits • Receivers (cont) • Frequency conversion process.

  13. G7 … Practical Circuits G7A • Receivers (cont) • A Product detector circuit is used to process signals from the IF amplifier and BFO and send the result to the AF amplifier in a single-sideband phone superheterodyne receiver.

  14. G7 … Practical Circuits G7A • Receivers (cont) • A direct conversion receiver is suitable for CW and SSB reception but does not require a mixer stage or an IF amplifier.

  15. G7 … Practical Circuits • Receivers (cont) • Compared to previous slide, this receiver has 2 IF’s, 2 mixers, and 2 oscillators, hence the term: Dual-Conversion Receiver.

  16. G7 … Practical Circuits G7A • Receivers (cont) • The simplest combination of stages that can be combined to implement a superheterodyne receiver is a HF oscillator, mixer, and detector.

  17. G7 … Practical Circuits G7A • Receivers (cont) • A Discriminator circuit is used in many FM receivers to convert signals coming from the IF amplifier to audio. Discriminator

  18. G7 … Practical Circuits G7A • Filters • The impedance of a low-pass filter as compared to the impedance of the transmission line into which it is inserted should be about the same. • A Filter might be used to process signals from the balanced modulator and send them to the mixer in a single-sideband phone transmitter. Filter

  19. G7 … Schematic drawing symbols • Symbol 3 represents a fixed resistor. • Symbol 13 represents a single cell battery. • Symbol 4 represents a NPN transistor. • Symbol 5 represents a variable capacitor. • Symbol 6 represents a transformer. • Symbol 11 represents a single pole switch.

  20. G7 … Practical Circuits G7B • Digital circuits • A “flip-flop” circuit is a digital circuit with two stable states. • Digital circuits use the binary number system because binary "ones" and "zeros" are easy to represent with an "on" or "off" state.

  21. G7 … Practical Circuits G7B • Digital circuits (cont) • The output of a two-input NAND gate, given both inputs are “one” is Zero.

  22. G7 … Practical Circuits G7B • Digital circuits (cont) • The output of a NOR gate given that both inputs are “zero” is One.

  23. G7 … Practical Circuits G7B • Digital circuits(cont) • There are 8 states in a 3-bit binary counter. • 000 001 010 011 • 100 101 110 111 • A shift register is a clocked array of circuits that passes data in steps along the array.

  24. G7 … Practical Circuits G7B • Amplifiers • Low distortion is a characteristic of a Class A amplifier. • A Class “C” power stage is appropriate for amplifying a modulated signal for the CW mode. • High efficiency is an advantage of a Class C amplifier

  25. G7 … Practical Circuits G7B • Amplifiers (cont) • The efficiency of an RF power amplifier is determined by dividing the RF output power by the DC input power. • A linear amplifier is an amplifier whose output preserves the input waveform. RF Output Power _____________________ Efficiency = DC Input Power

  26. G7 … Practical Circuits G7B • Oscillators • The basic components of virtually all oscillators are a filter and an amplifier operating in a feedback loop.

  27. G7 … Practical Circuits G7B • Oscillators(cont) • The phase shift of the RC feedback circuit determines the frequency of an RC oscillator. • (Placed in the positive feedback loop.) • The inductance and capacitance in the tank circuit determines the frequency of an LC oscillator.

  28. Element 3 General Class Question Pool Valid July 1, 2007 Through June 30, 2011

  29. G7A01 What safety feature does a power-supply bleeder resistor provide? • It acts as a fuse for excess voltage • It discharges the filter capacitors • It removes shock hazards from the induction coils • It eliminates ground-loop current

  30. G7A02 What components are used in a power-supply filter network? • Diodes • Transformers and transistors • Quartz crystals • Capacitors and inductors

  31. G7A03 What should be the minimum peak-inverse-voltage rating of the rectifier in a full-wave power supply? • One-quarter the normal output voltage of the power supply • Half the normal output voltage of the power supply • Double the normal peak output voltage of the power supply • Equal to the normal output voltage of the power supply

  32. G7A04 What should be the approximate minimum peak-inverse-voltage rating of the rectifier in a half-wave power supply? • One-half the normal peak output voltage of the power supply • Half the normal output voltage of the power supply • Equal to the normal output voltage of the power supply • Two times the normal peak output voltage of the power supply

  33. G7A05 What should be the impedance of a low-pass filter as compared to the impedance of the transmission line into which it is inserted? • Substantially higher • About the same • Substantially lower • Twice the transmission line impedance

  34. G7A06 Which of the following might be used to process signals from the balanced modulator and send them to the mixer in a single-sideband phone transmitter? • Carrier oscillator • Filter • IF amplifier • RF amplifier

  35. G7A07 Which circuit is used to combine signals from the carrier oscillator and speech amplifier and send the result to the filter in a typical single-sideband phone transmitter? • Mixer • Detector • IF amplifier • Balanced modulator

  36. G7A08 What circuit is used to process signals from the RF amplifier and local oscillator and send the result to the IF filter in a superheterodyne receiver? • Balanced modulator • IF amplifier • Mixer • Detector

  37. G7A09 What circuit is used to process signals from the IF amplifier and BFO and send the result to the AF amplifier in a single-sideband phone superheterodyne receiver? • RF oscillator • IF filter • Balanced modulator • Product detector

  38. G7A10 What is an advantage of a crystal controlled transmitter? • Stable output frequency • Excellent modulation clarity • Ease of switching between bands • Ease of changing frequency

  39. G7A11 What is the simplest combination of stages that can be combined to implement a superheterodyne receiver? • RF amplifier, detector, audio amplifier • RF amplifier, mixer, if amplifier • HF oscillator, mixer, detector • HF oscillator, product detector, audio amplifier

  40. G7A12 What type of receiver is suitable for CW and SSB reception but does not require a mixer stage or an IF amplifier? • A super-regenerative receiver • A TRF receiver • A super-heterodyne receiver • A direct conversion receiver

  41. G7A13 What type of circuit is used in many FM receivers to convert signals coming from the IF amplifier to audio? • Product detector • Phase inverter • Mixer • Discriminator

  42. G7A14 Which of the following is a desirable characteristic for capacitors used to filter the DC output of a switching power supply? • Low equivalent series resistance • High equivalent series resistance • Low Temperature coefficient • High Temperature coefficient

  43. G7A15 Which of the following is an advantage of a switched-mode power supply as compared to a linear power supply? • Faster switching time makes higher output voltage possible • Fewer circuit components are required • High frequency operation allows the use of smaller components • All of these choices are correct

  44. G7A16 What portion of the AC cycle is converted to DC by a half-wave rectifier? • 90 degrees • 180 degrees • 270 degrees • 360 degrees

  45. G7A17 What portion of the AC cycle is converted to DC by a full-wave rectifier? • 90 degrees • 180 degrees • 270 degrees • 360 degrees

  46. G7A18 What is the output waveform of an unfiltered full-wave rectifier connected to a resistive load? • A series of DC pulses at twice the frequency of the AC input • A series of DC pulses at the same frequency as the AC input • A sine wave at half the frequency of the AC input • A steady DC voltage

  47. G7A19 Which symbol in figure G7-1 represents a fixed resistor? • Symbol 2 • Symbol 6 • Symbol 3 • Symbol 12

  48. G7A20 Which symbol in figure G7-1 represents a single cell battery? • Symbol 5 • Symbol 12 • Symbol 8 • Symbol 13

  49. G7A21 Which symbol in figure G7-1 represents a NPN transistor? • Symbol 2 • Symbol 4 • Symbol 10 • Symbol 12

  50. G7A22 Which symbol in figure G7-1 represents a variable capacitor? • Symbol 2 • Symbol 11 • Symbol 5 • Symbol 12

More Related