'Receiver Overload', also known as 'Front-End Overload' or 'RF Overload', is a problem where the early stages of a receiver (i.e., RF amplifier or Mixer) are overwhelmed by some strong nearby transmitter. For example, TV reception is affected by an HF transmitter. In the case of 'Overload', the exact transmit frequency does not seem to matter: the effect is the same for a broad range of transmit frequencies. This contrasts with 'Harmonics' where a multiple of a given transmit frequency is the cause of the interference.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Receiver Overload', also known as 'Front-End Overload' or 'RF Overload', is a problem where the early stages of a receiver (i.e., RF amplifier or Mixer) are overwhelmed by some strong nearby transmitter. For example, TV reception is affected by an HF transmitter. In the case of 'Overload', the exact transmit frequency does not seem to matter: the effect is the same for a broad range of transmit frequencies. This contrasts with 'Harmonics' where a multiple of a given transmit frequency is the cause of the interference.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Receiver Overload', also known as 'Front-End Overload' or 'RF Overload', is a problem where the early stages of a receiver (i.e., RF amplifier or Mixer) are overwhelmed by some strong nearby transmitter. For example, TV reception is affected by an HF transmitter. In the case of 'Overload', the exact transmit frequency does not seem to matter: the effect is the same for a broad range of transmit frequencies. This contrasts with 'Harmonics' where a multiple of a given transmit frequency is the cause of the interference.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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key words: TV, OVERLOAD, HF. TV Channels begin at 54 MHz; the HF range ends at 30 MHz. To prevent overload to a TV receiver from an HF transmitter, a HIGH-PASS filter can be installed on the TV receiver to allow higher frequencies through while attenuating lower frequencies. The object of the filtering being to keep the HF signals out of the TV receiver.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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The proximity of a transmitter a short distance from a receiver, especially on the same band, may cause receiver overload. Symptoms can be loss of receiver sensitivity (desensitization) or weird noises.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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key words: IN THE BACKGROUND. In 2014, Innovation, Science and Economic Development Canada chose to replace the word "cross-modulation" with "intermodulation". 'Cross-Modulation' is a special case of overload: it too supposes a strong undesired signal. The peculiarity of 'Cross-Modulation' is that the two signals are heard at the same time: the one you want AND the undesired interfering signal.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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"Intermod" for short, a plague in urban environments. High-powered transmitters used for commercial purposes multiply the possibilities that two or more signals mix and produce a result (product) which OVERLOADS your receiver. The actual mixing may occur in your receiver, in which case filtering might be helpful, or elsewhere altogether. The results: loss of sensitivity, noises and squeals covering the intended signal in your receiver.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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"Intermod" for short, a plague in urban environments. High-powered transmitters used for commercial purposes multiply the possibilities that two or more signals mix and produce a result (product) which OVERLOADS your receiver. The actual mixing may occur in your receiver, in which case filtering might be helpful, or elsewhere altogether. The results: loss of sensitivity, noises and squeals covering the intended signal in your receiver.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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The proximity of a transmitter a short distance from a receiver, especially on the same band, may cause receiver overload. Symptoms can be loss of receiver sensitivity (desensitization) or weird noises.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Cross-Modulation' is a special case of overload. TV Channels begin at 54 MHz; the HF range ends at 30 MHz. To prevent overload to a TV receiver from an HF transmitter, a HIGH-PASS filter can be installed on the TV receiver to allow higher frequencies through while attenuating lower frequencies. The object of the filtering being to keep the HF signals out of the TV receiver.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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TV Channels begin at 54 MHz; the HF range ends at 30 MHz. To prevent overload to a TV receiver from an HF transmitter, a HIGH-PASS filter can be installed on the TV receiver to allow higher frequencies through while attenuating lower frequencies. The object of the filtering being to keep the HF signals out of the TV receiver.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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A frequent cause of interference to home entertainment systems is that the long speaker leads act as antennas and bring radio energy into the audio amplifier stages, audio rectification ensues. Keeping the RF out of the audio circuitry can be achieved by winding the speaker leads on ferrite cores to form a choke (high inductive reactance at RF).
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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"RFI Filter" = Radio Frequency Interference filter. Much like home entertainment systems with their long speaker leads acting as antennas, wire-line telephones with cabling running through the house and streets can easily pickup RF energy. Filters installed at the telephone set usually solve the problem.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Much like home entertainment systems, the long speaker leads in a Public-Address sound system act as antennas and bring radio energy into the audio amplifier stages. Interfering SSB signals are heard as distorted speech in the sound system. Interfering CW signals are heard as on-and-off clicks or hum.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Much like home entertainment systems, the long speaker leads in a Public-Address sound system act as antennas and bring radio energy into the audio amplifier stages. Interfering SSB signals are heard as distorted speech in the sound system. Interfering CW signals are heard as on-and-off clicks or hum.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Properly grounding all station equipment minimizes the radiation of RF which may couple into house wiring and affect other devices in the household.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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key words: ACROSS THE DIAL. This has to be a case of OVERLOAD. 'Cross-Modulation' and 'Audio Rectification' are two manifestations of overload. All other choices would not appear 'across the dial': an 'Harmonic' falls on a precise frequency, 'Splatter' is limited to a few kilohertz.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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key words: STRONG SIGNAL. 'Cross-Modulation' is a special case of overload. Nothing needs to be wrong with the affected receiver or the transmitter. It is simply that the receiver is exposed to more radio energy that it can handle. 'Rectification' leads to 'detection': any semiconductor device may start acting like a diode and perform the two functions.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Long wires act as antennas. The wires should be kept as short as possible. Winding speaker or telephone wires around a 'ferrite core' makes an Inductor (a coil). Inductors oppose (inductive reactance) high frequency AC signals such as radio frequency. The 'ferrite core' makes for more inductance even with only a few turns of wire. Ferrite is a material with electromagnetic properties.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Long wires act as antennas. The wires should be kept as short as possible. Winding speaker or telephone wires around a 'ferrite core' makes an Inductor (a coil). Inductors oppose (inductive reactance) high frequency AC signals such as radio frequency. The 'ferrite core' makes for more inductance even with only a few turns of wire. Ferrite is a material with electromagnetic properties.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Long wires act as antennas. The wires should be kept as short as possible. Winding speaker or telephone wires around a 'ferrite core' makes an Inductor (a coil). Inductors oppose (inductive reactance) high frequency AC signals such as radio frequency. The 'ferrite core' makes for more inductance even with only a few turns of wire. Ferrite is a material with electromagnetic properties.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Long wires act as antennas. The wires should be kept as short as possible. Winding speaker or telephone wires around a 'ferrite core' makes an Inductor (a coil). Inductors oppose (inductive reactance) high frequency AC signals such as radio frequency. The 'ferrite core' makes for more inductance even with only a few turns of wire. Ferrite is a material with electromagnetic properties.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Key-Clicks' in a CW Transmitter have two manifestations. One in DISTANT receivers, caused by "too sharp rise and decay times of the carrier", results in clicks being heard several kHz away from your operating frequency. The other in NEARBY broadcast receivers, caused by the "making and breaking of the circuit at the Morse key" (sparks), results in clicks being heard just like from other electrical devices where currents are switched. The first line of defence is a 'key-click filter' in the keying circuitry, but troubleshooting in later stages may be required in a modern transmitter.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Spurious Emissions': signals radiated at a frequency other than the operating frequency. Two examples: 'Harmonics', energy at integer multiples of the operating frequency. 'Parasitic Oscillations', unwanted oscillation above or below the operating frequency. Proper adjustment and shielding prevent this whole class of transmitter problems called 'Spurious Emissions'.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Spurious Emissions': signals radiated at a frequency other than the operating frequency. Two examples: 'Harmonics', energy at integer multiples of the operating frequency. 'Parasitic Oscillations', unwanted oscillation above or below the operating frequency. Proper adjustment and shielding prevent this whole class of transmitter problems called 'Spurious Emissions'.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Spurious Emissions': signals radiated at a frequency other than the operating frequency. Two examples: 'Harmonics', energy at integer multiples of the operating frequency. 'Parasitic Oscillations', unwanted oscillation above or below the operating frequency. Proper adjustment and shielding prevent this whole class of transmitter problems called 'Spurious Emissions'.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Key word: LOCAL. 'Key-Clicks' in a CW Transmitter have two manifestations. One in DISTANT receivers, caused by "too sharp rise and decay times of the carrier", results in clicks being heard several kHz away from your operating frequency. The other in NEARBY broadcast receivers, caused by the "making and breaking of the circuit at the Morse key" (sparks), results in clicks being heard just like from other electrical devices where currents are switched. The first line of defence is a 'key-click filter' in the keying circuitry, but troubleshooting in later stages may be required in a modern transmitter.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Key word: DISTANT. 'Key-Clicks' in a CW Transmitter have two manifestations. One in DISTANT receivers, caused by "too sharp rise and decay times of the carrier", results in clicks being heard several kHz away from your operating frequency. The other in NEARBY broadcast receivers, caused by the "making and breaking of the circuit at the Morse key" (sparks), results in clicks being heard just like from other electrical devices where currents are switched. The first line of defence is a 'key-click filter' in the keying circuitry, but troubleshooting in later stages may be required in a modern transmitter.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Key word: DISTANCE. 'Key-Clicks' in a CW Transmitter have two manifestations. One in DISTANT receivers, caused by "too sharp rise and decay times of the carrier", results in clicks being heard several kHz away from your operating frequency. The other in NEARBY broadcast receivers, caused by the "making and breaking of the circuit at the Morse key" (sparks), results in clicks being heard just like from other electrical devices where currents are switched. The first line of defence is a 'key-click filter' in the keying circuitry, but troubleshooting in later stages may be required in a modern transmitter.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Key-Clicks' in a CW Transmitter have two manifestations. One in DISTANT receivers, caused by "too sharp rise and decay times of the carrier", results in clicks being heard several kHz away from your operating frequency. The other in NEARBY broadcast receivers, caused by the "making and breaking of the circuit at the Morse key" (sparks), results in clicks being heard just like from other electrical devices where currents are switched. The first line of defence is a 'key-click filter' in the keying circuitry, but troubleshooting in later stages may be required in a modern transmitter.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Spurious Emissions': signals radiated at a frequency other than the operating frequency. Two examples: 'Harmonics', energy at integer multiples of the operating frequency. 'Parasitic Oscillations', unwanted oscillation above or below the operating frequency. Proper adjustment and shielding prevent this whole class of transmitter problems called 'Spurious Emissions'.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Spurious Emissions': signals radiated at a frequency other than the operating frequency. Two examples: 'Harmonics', energy at integer multiples of the operating frequency. 'Parasitic Oscillations', unwanted oscillation above or below the operating frequency. Proper adjustment and shielding prevent this whole class of transmitter problems called 'Spurious Emissions'.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Spurious Emissions': signals radiated at a frequency other than the operating frequency. Two examples: 'Harmonics', energy at integer multiples of the operating frequency. 'Parasitic Oscillations', unwanted oscillation above or below the operating frequency. Proper adjustment and shielding prevent this whole class of transmitter problems called 'Spurious Emissions'.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Unlike 'Overload' where a TV receiver is likely to be affected by a broad range of transmitter frequencies, interference to a single TV channel from a specific band of transmitter frequencies suggests 'Harmonics' are at play. 'Harmonic Radiation' entails integer (whole-number) multiples of the operating frequency. Apart from proper adjustment of the transmitter, a 'Low-Pass' filter with a cutoff frequency of 30 MHz helps curb harmonics out of an HF transmitter. Three times 21 MHz (15 m) affects TV channel 3 [60-66 MHz]. Four times 21 MHz affects channel 6 [82-88 MHz].
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Harmonic Radiation' entails integer (whole-number) multiples of the operating frequency. Harmonics result in 'out-of-band' signals: you may be heard on another harmonically-related band (e.g., 3 times 7 MHz (40 m) = 21 MHz (15 m) ) or interfere with other services. Apart from proper adjustment of the transmitter, a 'Low-Pass' filter with a cutoff frequency of 30 MHz helps curb harmonics out of an HF transmitter.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Harmonic Radiation' entails integer (whole-number) multiples of the operating frequency. Harmonics result in 'out-of-band' signals: you may be heard on another harmonically-related band (e.g., 3 times 7 MHz (40 m) = 21 MHz (15 m) ) or interfere with other services. Apart from proper adjustment of the transmitter, a 'Low-Pass' filter with a cutoff frequency of 30 MHz helps curb harmonics out of an HF transmitter.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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key words: POORLY TUNED TX, MULTI-BAND ANTENNA. Improper adjustment of the transmitter may cause it to put out 'Harmonic Radiation' (integer multiples of the operating frequency). The multi-band antenna will readily radiate these signals at other frequencies.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Harmonic Radiation' entails integer (whole-number) multiples of the operating frequency. Harmonics result in 'out-of-band' signals: you may be heard on another harmonically-related band (e.g., 3 times 7 MHz (40 m) = 21 MHz (15 m) ) or interfere with other services. Apart from proper adjustment of the transmitter, a 'Low-Pass' filter with a cutoff frequency of 30 MHz helps curb harmonics out of an HF transmitter.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Splatter': "unwanted emission immediately outside the normal necessary bandwidth", in other words, you interfere with other stations on adjacent frequencies. Too much microphone gain or too much speech processing may lead to 'Overmodulation', a major cause of 'Splatter'. Overmodulation can also force the Linear Power Amplifier into a non-linear zone of operation which leads to 'Harmonic Radiation'.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Harmonic Radiation' (integer multiples of the operating frequency). Harmonics of several amateur HF frequencies fall right on TV channels: Three times 21 MHz (15 m) affects TV channel 3 [60-66 MHz]. Four times 21 MHz affects channel 6 [82-88 MHz]. Twice 28 MHz (10 m) affects channel 2 [54-60 MHz].
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Splatter': "unwanted emission immediately outside the normal necessary bandwidth", in other words, you interfere with other stations on adjacent frequencies. Too much microphone gain or too much speech processing may lead to 'Overmodulation', a major cause of 'Splatter'. Overmodulation can also force the Linear Power Amplifier into a non-linear zone of operation which leads to 'Harmonic Radiation'.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Splatter': "unwanted emission immediately outside the normal necessary bandwidth", in other words, you interfere with other stations on adjacent frequencies. Too much microphone gain or too much speech processing may lead to 'Overmodulation', a major cause of 'Splatter'. Overmodulation can also force the Linear Power Amplifier into a non-linear zone of operation which leads to 'Harmonic Radiation'.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Harmonic Radiation' (integer multiples of the operating frequency). Harmonics of several amateur HF frequencies fall right on TV channels: Three times 21 MHz (15 m) affects TV channel 3 [60-66 MHz]. Four times 21 MHz affects channel 6 [82-88 MHz]. Twice 28 MHz (10 m) affects channel 2 [54-60 MHz].
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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'Splatter': "unwanted emission immediately outside the normal necessary bandwidth", in other words, you interfere with other stations on adjacent frequencies. Too much microphone gain or too much speech processing may lead to 'Overmodulation', a major cause of 'Splatter'. Overmodulation can also force the Linear Power Amplifier into a non-linear zone of operation which leads to 'Harmonic Radiation'.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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key word: HARMONIC. 'Harmonic Radiation' (integer multiples of the operating frequency). A 'Low-Pass' filter with a cutoff frequency of 30 MHz helps curb harmonics out of an HF transmitter. The 'Key-Click' filter (choke/capacitor) is used at the telegraph key to prevent 'key-click' interference. A 'High-Pass' filter is used on a TV receiver to prevent overload from an HF transceiver.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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key words: LOW-PASS. 'Harmonic Radiation' (integer multiples of the operating frequency). A 'Low-Pass' filter with a cutoff frequency of 30 MHz helps curb harmonics out of an HF transmitter.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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key words: BLOCKS ABOVE AND BELOW. A 'Band-Pass' filter lets frequencies between two design limits pass unaffected. Outside of that range, attenuation is present. A 'High-Pass' filter passes frequencies above a certain limit but attenuates lower frequencies. A 'Low-Pass' filter lets frequencies below its cutoff frequency pass unimpeded but attenuates higher frequencies.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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All filters are designed with a given impedance in mind. The source impedance and load impedance must match the design criteria of the filter for it to function optimally.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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key word: HARMONIC. 'Harmonic Radiation' (integer multiples of the operating frequency). A 'Low-Pass' filter with a cutoff frequency of 30 MHz helps curb harmonics out of an HF transmitter. A 'High-Pass' filter is used on a TV receiver to prevent overload from an HF transceiver.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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key word: HARMONIC. 'Harmonic Radiation' (integer multiples of the operating frequency). A 'Low-Pass' filter with a cutoff frequency of 30 MHz helps curb harmonics out of an HF transmitter. A 'High-Pass' filter is used on a TV receiver to prevent overload from an HF transceiver.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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A 'High-Pass' filter is used on a TV receiver to prevent overload from an HF transceiver. A 'Low-Pass' filter with a cutoff frequency of 30 MHz helps curb harmonics out of an HF transmitter.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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A 'Band-Pass' filter lets frequencies between two design limits pass unaffected. Outside of that range, attenuation is present. A 'Low-Pass' filter lets frequencies below its cutoff frequency pass unimpeded but attenuates higher frequencies. A 'Band-Reject' filter passes everything BUT a narrow range of frequencies.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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A 'Band-Reject' filter passes everything BUT a narrow range of frequencies. A 'Low-Pass' filter lets frequencies below its cutoff frequency pass unimpeded but attenuates higher frequencies. A 'Band-Pass' filter lets frequencies between two design limits pass unaffected. Outside of that range, attenuation is present.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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A 'High-Pass' filter is used on a TV receiver to prevent overload from an HF transceiver. A 'Key-Click' filter (choke/capacitor) is used at the telegraph key to prevent 'key-click' interference. A 'Low-Pass' filter with a cutoff frequency of 30 MHz helps curb harmonics out of an HF transmitter.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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key words: HIGH-FREQUENCY. A 'Low-Pass' filter with a cutoff frequency of 30 MHz helps curb harmonics out of an HF transmitter. The filter allows frequencies BELOW the cutoff to pass freely but attenuates frequencies above the cutoff. The HF segment of the radio spectrum spans 3 MHz to 30 MHz.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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