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This type of filter can be used in a Mode J satellite station (uplink on 2m, downlink on 70cm) to reduce the problem of the uplink signal desensing the receiver

Sherwood Engineering Inc., based in Denver, Colorado, specializes in ham radio accessories and components. The company, located at 1268 South Ogden Street, offers a variety of products including filters, cooling kits, and audio switch boxes. Sherwood Engineering is known for its work with brands such as _Drake_, _Icom_, and Collins, providing components like 455 kHz mechanical and crystal filters. The company has also been involved in producing first-IF roofing filters and DSP protection filters. Sherwood Engineering has a history of over 45 years in the industry, though it has now retired from producing certain products like the SE-3 MK IV. Despite this, the company continues to provide technical resources and presentations on optimizing rig performance, with past events held at venues like the Dayton Contest University in 2014. The company operates Monday through Friday, from 9 a.m. to 5 p.m. Mountain Time, and accepts payments via PayPal, check, or money order. DXZone Focus: Denver | Filters | Icom

The Rock-Mite is a 40m CW kit offered by Small Wonder Labs . It features built-in keyer, direct conversion receiver with a crystal RF bandpass filter, 500 milliwatts of power, and switchable frequency offsets to work around QRM

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.

A homemade tunable bandpass filter for all HF bands from 160m to 10m

As the sunspots return and DX propagation conditions to improve, the age old problem with QRM begins to show up on the amateur bands. Thif filter help you on improving reception

Coaxial stub filters used at W7GJ

GQRX is a free and simple to use SDR receiver which runs on Linux and MacOS X. GQRX comes with a standard FFT spectrum and waterfall display and a number of common filter settings

Ham radio equipment eBay prices, adjusted for trends, filtered for accessories, leaving only condition and auction terms to affect the final price. Also direct links to auctions, searches and recommended sites for research, plus amateur radio station rigs, projects and antenna farm.

Fill out the form to design a bandpass filter as described in the January 1985 issue of Ham Radio Magazine. These filters are generally limited to frequencies above 200 MHZ because their size is slightly longer than 1/4 wavelength

Project of receive only filters optimized for minimal loss and very high rejection of frequencies below 75% of the filter center frequency by K1TTT

Project to build sets of band pass transmitting filters for reducing the interference between HF transceivers operated in close proximity

High pass filter schematics for TVI and examples of finished filters

The County Hunting software, version **6.1**, is designed for amateur radio operators focused on USA-CA Award tracking and logging. This application supports _Windows_ environments and facilitates the import and export of ADIF files, enhancing QSL management by integrating electronic confirmations via LoTW and e-QSL. The software has been updated to align with the new award rules managed by MARAC, following the discontinuation of CQ magazine's involvement. Users can visualize QSLs post-scanning and benefit from enhanced ADIF import functionality. Version 5.4 introduced accelerated county searches via FCC databases, with filters for QSL confirmations and e-QSL enhancements. The software also includes a feature for backing up and restoring QSOs by LoTW confirmations. Visual County tools have been refined, offering improved map interactions and the addition of county flags. The software supports various digital modes including FT8, FT4, and SSTV, and includes functionality for PSK250 and 60m bands. The application is multilingual, with support for Italian, English, French, and Spanish, and provides automated updates and web-based county searches. DXZone Focus: County Hunting | ADIF | Windows | LoTW

A K9AY loop antenna project done with Far Circuits pc boards for the antenna switch and bandpass filter and preamp by K7SFN

This is an interactive filter design package, for designing digital filters

An improved version of DK9NL QRM Killer, with dedicated noise sampling antenna for completely filtering of plasma TV rattle on HF bands

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.

Taking the venerable SMK-1 design to 20m and adding an RF amp, audio filter, and a TiCK Keyer ... by Wayne McFee, NB6M

This article is about the characteristics and use of various filters and ferrites for solving amateur radio electromagnetic compatibility problems involving breakthrough of amateur signals into domestic equipment such as television sets, video recorders stereo sytems etc.

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.

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

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

Notes about generating RF sweep signals on the Arduino for filter testing, a digital version of the old Wobbulator concept

Australia's largest range of Electronic Kits & Components In Stock for the Radio Experimenter, ATV, microwaves, HF Band pass filters

A simple project for an effective home made band pass filter, designed for the portable field day usage

Supplying Toroids, Electronic Parts and Kits to Engineers, Schools and Hobbyists. Capacitos, filters, inductors, qrp products

Article explaining electronic network of low pass filters

How to design narrowband bandpass filters

Communication Coil, Inc. designs and produces custom, high reliability Filter Networks, RF Coils, Chokes, Inductors, Baluns, Toroids and Power Magnetics for communications

Online calculator, Butterworth Bandstop (Notch) Filter Designer

This sweeper built for a narrow bandwidth filter adjustment, use a simple 555 version sawtooth wave generator.

Products and books for the radio hobbist. Antennas, Coax cables, filters,Lightning Protection, Wire & Cable, Books

ScopeIIR: an Infinite Impulse Response (IIR) digital filter design tool for Windows. It designs high-order IIR filters based on analog filter prototypes, and can design lowpass, highpass, bandpass, and bandstop filters.

The direct conversion receiver described consists of only a bandpass filter, mixer IC, VFO and audio filter. With only 22 parts, this simple circuit should take a few hours at the weekend to construct.

Cutting out the noise using a simple coax filter to improve the poor front end filtering

Maker of filters, oscillators, cristals Coils, Toroidal Inductions, Solenoids, Bifilar wound Solenoids, Trifilar Solenoids and Transformers Located in Kansas City, Missouri

Ham rasio shop in Chzeck republic, offer antennas, filters, roators, electronic components, cw keyers, power supplies, and other ham shack accessories

Clean Up Your Signals with Band-Pass Filters

An home made low pass filter for 70 MHz by IK0VAQ

A combined 144MHz Low-Pass and 432 MHz Notch Filter by VE2ZAZ

Radio Filters manufactures low price fm notch filters.

HF receiving systems and components, band pass filters, array controllers, HI-Z pre amplifiers

Will additional coax stubs improve Band Pass Filter performance?

Desgining crystal filters and find out crystal data by measuring it.

An illustrated modification for the Icom IC-R20 receiver to locate and use the unfiltered audio.

Online high pass filter design page with introduction to high-pass filters by K7MEM

Unfilter LF output from the TH215/415 kenwood portable radio

CW and SSB INRAD narrow filters modification

Last 15 minute Reverse Beacon Network spots on live graph, let you filter by dx spot continent or spotter continent, as well as by band and let you reduce bandwidth