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Last Updated
03/31/2019
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Detailed entries for one subject from the INDEX TO HOW TO DO IT INFORMATION. |
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RADIO FREQUENCY INTERFERENCE FILTER sa AUDIO FILTER xx AUDIO FILTER xx FILTER (ELECTRONIC) xx RADIO FREQUENCY INTERFERENCE Filtering unwanted RFI (radio frequency interference) out of audio equipment. A simple switchable low pass RFI filter removes ham radio and CB radio interference that is being picked up by a phono cartridge. Improve any audio system by adding an RFI (radio-frequency interference) line filter to the 120VAC outlet box that serves your system. Tip on filtering all zeners (including 3-terminal regulators) to reduce RFI. Your power line, just 60 Hz. A review of interference from AC power lines, fluorescent lamps and switching power supplies that can affect the performance of audio systems. Describes the use of a commercial power-line filter (the Adcom ACE-515 AC enhancer) to reduce the problems. AC line filter for use with a Philips-style CD player. Using differential circuits in AC power supplies and amplifiers to effectively reduce hum and noise. Broadcast-band notch filter uses a series-resonant "wave trap" to eliminate an interfering broadcast signal without affecting receiver sensitivity in the SW bands. Mobile filter eliminates ignition noise from 2 meter walkie-talkie style transceivers which get their power via an automobile cigarette lighter plug. Conquering front-end overload in the TS-940S. Simple filter circuits cure interference caused by a nearby broadcast station. RFI (radio frequency interference) and the novice. Some basic information about its causes and remedies. Part 1. High- and low-pass filters for TVI. VCR inteference. RFI (radio frequency interference) and the novice. Some basic information about its causes and remedies. Part 2. Benefit of ferrite chokes. Build a "synthetic" crystal filter to plug into your headphone jack which does a better job than RC active filters in screening out nearby RF noise. Features two CW bandwidths, two phone bandwidths, and two notch filters. Eliminate powerful AM broadcast-band interference with amateur radio receivers. Using wave traps, a band-rejection filter, and/or a ladder attenuator. Includes construction notes. QRN Squasher MK-II. How to build an inexpensive noise-reduction circuit that will cancel up to 50 dB of local manmade electrical noise with minimal or no reduction in the strength of the desired signal. FM interference filter. Four-bit filter. Simple filter attaches to TV antenna leads and tunes out CB radio interference. Est. cost: $.50. Basic AM trap circuit can prevent AM signals in AC power line from getting into audio equipment. Simple capacitive filter circuit to eliminate RFI spikes from the AC power line. Such spikes can be caused by automatic light controllers. Cure the interference problems common to older, less sensitive radio receivers (antique radios) with this simple wave trap. Tip on need for a power-line outlet box with built-in toroid line filters to prevent computer-induced RFI from affecting telephones, TV, etc. Build a BCB (broadcast band) trap that connects between your antenna and shortwave receiver and blocks strong local BCB signals. Static smasher. Bandpass filter uses a capacitor and an inductor connected in parallel to pass only a narrow band of frequencies. It helps eliminate interference from electrical sources. Rotary switches on the filter allow a choice of 28 different passbands to choose from. Simple quarter-wavelength traps made from 300-ohm TV twin-lead transmission line are used to eliminate cordless telephone (FM) interference on television receivers. TVI filter attaches to your television antenna terminals and filters out CB radio interference. Schmetic for a harmonic trap to help eliminate TV interference caused by your CB radio. High-pass filter for TV set will filter out citizens band signals. Filter circuit to remove CB interference from TV signal. Reduce television interference on 6-, 10- and 11-meter bands with this tuned bandpass filter. Noise and interference filter for shortwave receiver. Active audio filter improves selectivity with a cutoff frequency of 3 KHz. Est. cost: $8. A hi-lo pass filter for a CB transceiver. It drains off dc or low frequency signals caused by static electricity build-up on the antenna and it reduces interference to nearby TV receivers. Active filter sharpens CW reception. Provides 6-dB selectivity of less than 100 Hz. Uses an op-amp in the circuit. Est. cost: $15. CB interference with TV. Part 1. Using a high-pass filter or series-tuned wave trap to overcome "fundamental blocking", a primary cause of TV interference from CB radios. Signal trap filter can eliminate false shortwave signals caused by a nearby AM station. Power line filter to insulate radios from fluorescent lamp interference. Coaxial capacitors can quiet interference caused by electric motors in automobiles. How to install ceramic capacitors in a hi-fi amplifiers power supply in order to eliminate diode transients which can cause interference on the AM band. Active outboard filter for low-cost ham radio rigs improves Morse code readability by improving selectivity and reducing interference. Tip on installing a wave trap to filter out unwanted AM radio signals. Make a lowpass-filter that inserts between microphone and preamp and reduces RF electromagnetic interference getting into ham transmitter. Circuits for a typical LPF (lowpass filter) and HPF (highpass filter) which can help eliminate radio interference and prevent overloading the front end of a receiver. Tunable bandpass filter circuit for use in the 40-meter band. Circuit for an absorptive filter to block television interference, especially on Channel 2 (54-60 MHz). How to overcome AM broadcast band interference. Includes a simple high-pass filter circuit that reduces the amplitude of standard BCB signals before they can overload a high-frequency or shortwave receiver. Make your own filters to eliminate CB interference from TV or stereo sets. Tip: How to add disc capacitors to a hi-fi system to cope with interference from CB or ham sets. How to get rid of RFI (radio frequency interference) in your hi-fi system. Includes use of filters and adjustments to your equipment. Simple and inexpensive way to eliminate harmonic interference utilizes a 1/4-wavelength transmission line stub. Interference traps for shortwave listeners and longwave enthusiasts. Eliminate interference from strong, local, braodcast-band (AM radio) stations. Curing electromagnetic interference. Part 3. How to head off interference before it enters your electronic equipment. Also, how to deal with power-line transients. Using ferrite rings to suppress RFI on external wires. Tips on filtering out a nearby AM radio station's RF that is being picked up by an audio amplifier. | |||||||||
Copyright © by Norman Lathrop Enterprises. All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means (electronic, mechanical, print photocopying, recording or otherwise) without the prior expressed permission of Norman Lathrop Enterprises, except as permitted by law. |
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