noise filter

Multiband wire antennas and ATUs  ^pop - DC1YB experience on multiband wire antennas. In particular examine FD4 windom and G5RV antenna, considering noise levels and matching aspects. Author reviews also the usage of Automatic antenna tuners in TS-50 TS-480 and GC-3000

T2FD, The Forgotten Antenna - The terminated. tilted, folded dipole T2FD is a little known antenna that performs excellently. Compact in size compared to a half­-wave dipole the T2FD provides signal gain, wide frequency coverage, and exceptionally low noise characteristics.

Chokes Explained - A "choke" is the common name given to an inductor that is used as a power supply filter element. They are typically gapped iron core units, similar in appearance to a small transformer, but with only two leads exiting the housing

Remotely-tuned loop antenna for LW and MW - This article describes how to build a loop antenna for low frequency (LF) and medium wave (MW) reception with remote-controlled tuning. The antenna is extremely sensitive and can be built mostly from parts from old radios and tape recorders. Like all loop antennas, it is highly directional, which allows you to null out unwanted noise sources.

DXFun Web Cluster - DX Cluster mainly in spanish, with chat, filtering available upon user registration, propagation reports and solar status, includes also latest dx news.

Amateur Radio Techniques - RF Filters an adjustable j-pole antenna manufacturer based in greece

Micro908 Kit - A re-usable control & computing platform for antenna measurement, PSK31 digital modems, audio filtering, signal source & VFO, memory keyer by AMQRP

Trilithic - Broadband instruments, R and microwave components and filters, field analyzers, spectrum analyzers

Slow CW Sensitivity - DK8KW laboratory tests to get some indication about the ability to communicate with signals below noise level using Slow-CW.

Getting started on RTTY - A complete guide from the station setup, rtty software customization, tips on tuning rtty signals and setting the proper audio level and filters by Andrew G8GNI M5AEX

Phase Noise. - This is perhaps the most important parameter in many oscillators and it deserves an in-depth discussion on what it is, how it affects a system and how it can be minimised in an oscillator design.

Radio Astronomy Supplies - Radio Astronomy Supplies astronomy products since 1994 including radio telescopes, LNA's, noise callibration source, books, videos.

Qucs - Quite Universal Circuit Simulator Priority listing - Qucs, briefly for Quite Universal Circuit Simulator, is an integrated circuit simulator which means you are able to setup a circuit with a graphical user interface (GUI) and simulate the large-signal, small-signal and noise behaviour of the circuit. After that simulation has finished you can view the simulation results on a presentation page or window. Run on Linux.

Audio processor for SSB transceiver - This circuit consists of microphone amplifier and a high pass filter. Suitable to improve signal readability.

Diplexer design notes - Standard diplexer design is based on singly-terminated Butterworth filters.

A low cost UHF/VHF duplexer - Duplexers for dual band radio are usually high pass filter and low pass filter combined in the same box. This circuit is a design within a cost of US$10.

YCCC 6 Band Receive Bandpass filter - This is a 6 band receive only filter designed to protect your receiver front end and provide 45dB reject at the stop bands.

The NVARC Ugly ¯ Filter Project - Project to build sets of band pass transmitting filters for reducing the interference between HF transceivers operated in close proximity

Narrow Band-Pass filter for HF - Band-pass filters can be critical components in competitive stations. This setup may help put your station on the map.

Clean Up Your Signals with Band-Pass Filters - These inexpensive, easily built filters can be the buffer you need between the signals you want to hear and send and those you don’t!

Clean Up Your Signals with Band-Pass Filters part 2 - Part 2—You’re now much closer to saying goodbye to your unwanted signal problems!

Band-Pass Filters for HF Transceivers - Do your multiple-transmitter field day or contest efforts suffer from intrastation interference ?

K2TR Coax Stub Filters - Multi transmitter filters

Easy bandpass filters - Quick and easy bandpass filters for receiver input by George Dobbs G3RJV

Second-Harmonic-Optimized Low-Pass Filters - Sometimes we need a little more output filtering than traditional designs offer. Look at a new filter that can give you that extra boost. QST article by W3NQN