noise filter

Common Mode Choke Theory - A common mode choke may be used to reduce a type of electrical noise known as common mode noise. Electro-magnetic interference (E.M.I.) in the circuit's environment is one source of electrical noise.

A Horn Antenna for 2.4 GHz. - This Antenna is not really practical for AO-40 reception, but horn antennas have a number of qualities useful in microwave antenna testing and noise figure measurements.

The K6STI Receiving Loop - This relatively unknown antenna does an amazing job pulling weak low band signals out of man-made noise backgrounds

G/T Simulations - by VE7BQH - Here you will find information on how antennas behave when stacked G/T is an important figure-of-merit for the antenna's overall receive performance, because it balances forward gain (G) against received thermal noise (T).

6m Half wave vertical - This antenna is very useful for receiving or scanning purposes, but you can use it for transmitting, too. It is 2,94m long and has a pi-configuration (Collins-Filter) for the matching.

eham DX Spots - DX Spots web cluster interface with filtering features available to eham subscribers

BHI Ltd - Noise eliminating products. Remove unwanted background noise and interference leaving only the speech. Clear communications, listen stress free. Dsp noise cancellation solutions.

RFAC Solutions - RF Connectors Cable Assembly Attenuators Filters High Power VHF Amplifiers, Adapters MMCX MCX SMA SMB SMC BNC TNC N from RFAC Solutions

SSB Electronic USA - manufactures and distributes HF, VHF, UHF and SHF equipment covering 10MHz. - 47.0GHz. Our products include: Wireless LAN / WAN Bidirectional Linear Amplifiers, Low Noise Preamplifiers - LNA's, RF Linear Amplifiers, Relays, Transverter Systems, Frequency Translation Systems, Downconverters, Antennas, Parabolic Dishes, Coaxial Cable, Relays, Antenna Switches, Microwave Test equipment, PC controlled Receivers, Microwave Linear Amplifiers including models for Telemetry, Wireless, and CDMA applications.

Heinz Bolli AG - Antenna tuners, components, filters and baluns manufacturer based in germany

Communication Concepts, Inc. - Provide components to the amateur who wants to construct their own gear and to the professional who wants to save money and time in prototyping their circuit design, Filters, HF Amplifiers, Splitter Combiners, VHF Amplifiers, ATV

Radiofilters - Radio Filters manufactures low price fm notch filters.

International Crystal Manufacturing Company - International crystal manufacturing provides quartz crystals, oscillators, precision crystals, filters, tcxos / vctcxos, qcm crystals, and other frequency control products. read details about our crystals and frequency control products and services.

Sherwood Engineering Inc. - Cooling kits, drake filters, speach processors, audio switch boxes, synchronous AM detectors,

Less White Noise - FT-897D Modification - Modification for FT-879D to remove the white noise spreaded far above 3 kHz by Petr OK1FIG

All American - Distributor of electronic components, ull range of semiconductors (active components), including relays, circuit breakers, transistors, diodes, memory devices, microprocessors, microcontrollers, and other integrated cuircuits, as well as passive components, such as capacitors, resistors, inductors, and electromechanical products, including cable, switches, connectors, filters, and sockets.

FreqTweak - FreqTweak is a tool for FFT-based realtime audio spectral manipulation and display for Linux. It provides several algorithms for processing audio data in the frequency domain and a highly interactive GUI to manipulate the associated filters for each. It also provides high-resolution spectral displays in the form of scrolling-raster spectrograms and energy vs frequency plots displaying both pre- and post-processed spectra.

A low pass filter circuit - A simple 7 element, Chebyshev low pass filter, rolls of at 30MHz. Attenuation is better than -40dB at 60MHz, -65dB at 90MHz, -80dB at 120MHz.

A diode-switched band-pass filter - High speed silicn diodes work well as RF switches. This article describes how to use diodes for selecting two or more filters ARRL QST article by W1FB

Band filters by PA9M - Band filters for PA6Z made by PA9M, designed by W3NQN.

Hombrewing an HF Transceiver - This page will describe the construction of a multi band SSB transceiver with all its components Band Pass Filter, Oscillator/Modulator unit, RX/TX Mixer TX Amp I.F. Amplifier AGC VFO Driver amplifier Receive audio amplifier Final amplifier Low pass filter Digital display and VFO stabiliser

Common-Mode Noise - Receiving Common Mode Noise shows how lack of a balun can contribute to system noise

Automotive RFI elimination - ARRL pdf file on how remove car noise from your radio. Modern vehicles are RF noisy environments. Come learn how to identify and silence yor mobile noise sources, by WA6PDP

ARRLWeb: Solving Ignition Noise RFI - Solving Ignition Noise RFI article. Help on removing noise interfences caused by ignition

Alternators & Batteries - Influence of batteries on RFI and noise generation by k0bg