6.1 Demonstrate knowledge of e.m.c. in respect of problems that can be caused when an amateur station operates in close proximity to other electronic equipment.
6.2 Describe and explain interference sources.
6.3 Describe and explain the various paths by which interfering signals can arrive at domestic TV, radio and audio equipment.
6.4 Describe and explain methods of improving the immunity of affected equipment.
6.5 Describe and explain methods of improving the amateur station design to reduce e.m.c. problems.
6.6 Explain the steps to be taken when investigating e.m.c. problems.
6.7 Describe and explain the e.m.c. considerations relating to the installation of transmitters in vehicles.
6.1 E.M.C.: the ability of a device, equipment or system to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbances to anything in that environment. and E.M.C.: problems that are likely to occur when an amateur station operates in close proximity to other electronic equipment.
6.2 Equipment used in an amateur station that is capable of generating broad band and narrow band interference.
6.3 Interfering signal paths: r.f., i.f., audio and mains borne
6.4 Methods of improving the immunity of affected equipment
6.4.1 use of toroidal chokes and filters (mains, high pass, low pass, bandpass, notch or band-stop)
6.4.2 characteristics of filters, bandwidth, insertion loss and impedance
6.4.3 screening, lead lengths, and fitting ferrite rings and beads and bypass capacitors.
6.5 Improving station design
6.5.1 r.f. grounding
6.5.2 station mains filtering
6.5.3 screening
6.5.4 monitoring output power and calculations of field strengths
6.5.5 use of minimum transmitted power
6 .5.6 monitoring output transmission for spurious and harmonic levels, including key clicks
6.5.7 location of antennas and masts
6.5.8 type and size of antennas
6.5.9 use of screened feeder cables, balanced lines and baluns.
6.6 Method of approach and basic checks required when investigating e.m.c. problems.
6.7 E.M.C. considerations for mobile installations
6.7.1 location of transceiver and connection to 12V supply
6.7.2 routing of d.c. power and antenna cables
6.7.3 location and grounding of antenna
6.7.4 possible effects of r.f. on vehicle electronic systems.
7.1 Define the basic terms.
7.2 For electromagnetic waves
7.2.1 explain their generation
7.2.2 state the relationship between electric and magnetic components.
7.3 For the ionosphere, troposphere and upper atmosphere
7.3.1 describe in simple terms the structure of the ionosphere
7.3.2 explain in simple terms, the refracting and reflecting properties of the ionosphere and the troposphere
7.3.3 explain the factors which affect the ionization of the upper atmosphere
7.3.4 state the effect of variations of ionization of the upper atmosphere on the propagation of electromagnetic waves.
7.4 Describe, in simple terms, ionospheric (or skywave), ground wave and tropospheric propagation.
7.5 Explain fading and forms of fade out.
7.6 For radio waves
7.6.1 state their velocity in free space
7.6.2 state the relationship between velocity, frequency and wavelength
7.6.3 calculate frequency and wavelength from given data.
7.7 For antennas and transmission lines
7.7.1 describe and explain their operation and construction
7.7.2 explain the principles of coupling and matching antennas to transmitters and receivers
7.7.3 identify from diagrams typical coupling and matching arrangements: antenna tuning units (a.t.u.); simple types based on the parallel tuned circuit; networks.
7.8 Describe balanced and unbalanced feeders and explain the principles of propagation of radio waves along transmission lines; the causes and effects of standing waves.
7.1 Explanation of basic terms: ionosphere, troposphere, atmosphere, field strength, polarization, maximum usable frequency, critical frequency, skip distance, sunspot cycle.
7.2 Generation of electromagnetic waves; relationship between electric and magnetic components.
7.3 Structure of the ionosphere. Refracting and reflecting properties of the ionosphere and troposphere. Effect of sunspot cycle, winter and summer seasons, and day and night on the ionization of the upper atmosphere; effect of variations of ionization on the propagation of electromagnetic waves.
7.4 Ground wave, ionospheric and tropospheric propagation.
7.5 Fade out and types of fading, including selective fading. Polarization, absorption and skip.
7.6 Velocity of radio waves in free space; relationship between velocity of propagation, frequency and wavelength; calculation of frequency and wavelength.
7.7 Receiving and transmitting antennas. Operation and construction of typical antennas, including multiband and directional types: end fed, dipole, ground plane, Yagi and quad. Their directional properties; polar diagrams. Coupling and matching.
7.8 Transmission lines: balanced and unbalanced feeders; elementary principles of propagation of radio waves along transmission lines; velocity factor, standing waves.
8.1 For the measurement of a.c., d.c. and r.f. voltages and currents
8.1.1 state the types of instrument in common use; analogue and digital meters, multimeters, oscilloscopes
8.1.2 explain how errors can be caused by the effects of the instrument on the circuit.
8.2 Explain the method of measurement of d.c. power input and r.f. power output of power amplifiers. Explain how power may be expressed in dBW. Calculate, from given values, d.c. power input, r.f. power output, efficiency and dissipation.
8.3 For frequency measuring instruments (absorption wavemeters, crystal calibrators and digital frequency meters)
8.3.1 state the purposes for which they are used
8.3.2 state their relative accuracy
8.3.3 describe in detail their use at an amateur transmitting station.
8.4 Describe the construction of dummy loads and explain their use.
8.5 Explain the purpose and method of using a standing wave ratio meter.
8.6 Describe the method of using an oscilloscope to display waveforms.
8.1 Types of instrument used for the measurement of ac., d.c. and r.f. voltages and currents errors in measurement; analogue and digital meters, multimeters, oscilloscopes.
8.2 Measurement of
8.2.1 d.c. power input to power amplifiers
8.2.2 r.f. power output of power amplifiers
8.2.3 efficiency and dissipation.
8.3 Purposes, operation and use of absorption wavemeters, crystal calibrators and digital frequency meters; relative accuracies.
8.4 Dummy loads, their construction and use in adjusting transmitters.
8.5 Circuit and use of standing wave ratio meters.
8.6 Setting up and use of an oscilloscope to examine and measure waveforms.
(Reproduced by kind permission of The City & Guilds of London Institute)
