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Dowwnload this free windows programs to design Butterworth, Chebyshev, Elliptic (Caur), Bessel, Legendre and Linear Phase low-pass, high-pass, band-Pass, and band-reject filters. Coupled Resonator band-pass filters

Freeware real time DSP filter particularly for applications of amateur radios , IIR, FIR filter, low-pass, high-pass, band-pass filter, band suppressor (notch filter) individually adjustable

Do your multiple-transmitter field day or contest efforts suffer from intrastation interference ?

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!

The page provides detailed information on coax stub filters for multi-transmitter setups, including specific lengths for different bands and types of coax. It also references additional technical notes for further analysis.

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

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

This is a 6 band receive only filter designed to protect your receiver front end and provide 45dB reject at the stop bands. This is a 6-band receive only filter designed to protect your receiver front end and provide 45dB reject at the stop bands. Stop band reject may be limited by the relay isolation. Worse case isolation is at 28 MHz or 35 dB or better. Relay K3/K8 protects the filter during transmit via the PTT line. A 25-50ms delay must be used between transmit and PTT. Do not rely on your radio to provide adequate delay with out using the PTT. You logging software must be set to allow a delay between PTT and time of 1st transmit. This filter will not work with VOX or QSK keying as you will damage the filter.

The document is a technical guide on designing RF filters for radio frequency applications. It covers topics such as interference suppression, band-pass filters, and low pass filters, with a focus on filter design and circuit filters.

Part 2 You're now much closer to saying goodbye to your unwanted signal problems!

A home made antenna tuner based on the W6JJZ basic concept that ,atches balanced loads without the use of lossy baluns, can provide band-pass filtering and harmonic attenuation.

Third-order Cauer filters can boost performance of multi-transmitter, multi-operator contest stations to the next level. The filters are practical and you don’t need expensive test equipment to align them.

Tips on winding wire coils used as inductive loads, traps, band-pass filters, are implemented in a number of amateur radio projects especially antenna projects

Clean Up Your Signals with Band-Pass Filters, a two-parts article published in this PDF file from a June 1998 QST article

Clean Up Your Signals with Band-Pass Filters

Passive Band-Pass Filter, low-pass filter calculator

Cavity is often required at a busy site to not only prevent its receiver from being overloaded by off-frequency signals, but also be a good neighbour and prevent low-level signals from your transmitter from getting into other users receivers - not to mention the preventing of those other signal from getting back into your transmitter to generate spurious signals in its own right.

This webpage caters to EMRFD owners, offering insights into building popcorn receiver band-pass filters with Ladpac programs and EMRFD Chapter 3 knowledge. Through practical experiments and Ladpac tools, the author explores coupling capacitors' impact on filter response and return loss optimization. The content emphasizes empirical approaches, encouraging builders to embrace experimentation and learn from mistakes. Detailed examples and workflow suggestions aid hobbyist-level designers in creating customized filters, fostering a deeper understanding of filter design principles.

Andrew Roos (ZS6AA) details his practical approach to building a Single Operator Two Radio contest station within suburban constraints. The article explains how he leveraged a Force-12 C-31XR triband beam's unique separate feed arrangement to operate on two bands simultaneously. Using band-pass filters and an antenna switch, he achieved sufficient isolation between bands without requiring multiple towers. The setup includes automatic band selection, audio switching, and computer control. Testing during the 2007 CQ WPX CW contest confirmed the system's effectiveness, demonstrating that competitive SO2R operation is achievable with limited space and budget.