low voltage

low voltage

Antennas : Feed Lines

• SWR: Maximum allowable VSWR - VSWR (voltage-standing-wave-ratio) represents the degree with which an antenna is "matched" to the system impedance. Most modern antennas do not require any tuning for optimum performance. VSWR is one of the easiest parameters to measure and VSWR meters are becoming very popular antenna installation tools
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• Magnetic Loop Antenna Calculator - Free windows program to calculate magnetic loop antenna.This small loop antenna calculator allow to determine capacitance and voltage based on Loop circumference, desired resonant frequency, conductor diameter and the operating power
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• T2FD Antenna - Terminated and twisted folded dipole - T2FD is a 600-900 ohms folded dipole, terminated with resistor. Feed impedance is coupled with 50/600 ohms voltage balun. It is a wide band antenna with rather low SWR over the full designed frequency range: antenna tuner is seldom needed.
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• Long Wire Antenna for portable operations - With the view to establish a quick and easy multi-band antenna deployment for portable and camping operations a simple long wire antenna with an earth or earth plus counterpoise arrangement with a 9:1 voltage unun including a tuner or simply with a tuner is one possible solution. With the 9:1 voltage unun and wire lengths suggested in the below tables the antenna should present non extreme impedances for all HF amateur band frequencies. This page is far from complete and represents the ongoing investigation into this type of antenna. Experiments to date seem to have raised more questions than obvious answers.
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• Antennas for QRP Operation - Antennas for low-power operation resemble those for 100W use. Minor adjustments, like capacitor voltage ratings, may apply, but basic principles persist. Portable antennas, notably Backpack Antennas for weight-conscious setups, hold relevance beyond QRP. While some antennas function acceptably at higher power, efficiency issues arise at QRP levels. Testing antennas at 100W exposes weaknesses, particularly in tuners, crucial for efficient QRP operation.
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• Repair or Replace Electrolytic Capacitors - For low voltage applications, like cathode bypass capacitors, most vintage types have an axial configuration, which is less common today but still available. Electrolytic power supply caps likely constitute the single worst liability in old audio, radio and test equipment. Rap about Electrolytics, Reforming, Chassis-Mount Replacements, Under-Chassis Installation, Rebuilding Capacitors
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• A cheap S Meter - A low-level voltage meter and could even be used for audio purposes.
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• Locating Power Line Noise - RF interference from power lines is caused by arcing as high voltage electricity bridges a gap to a lower ground potential on the power pole. Corroded or loose connections, cracked insulators almost all of the hardware on a power pole can be the source of arcing.
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