filter design

9 element yagi for 2 meters band  ^pop - A simple design of a 9 elem. yagi antenna for 2 meters band

H5ANX Mk4 Delta Loop Design - Delta loop antennas design by Sajid Rahim

A Vertically Polarized Delta Loop for 40m  ^pop - Practical contruction and designing notes of a delta loop for the 40 meters band

Plumbers Delight J Pole Antenna Project - This article was reprinted to assist new hams at building their own 2 metre antenna. This design is very rugged and can be built for a few dollars with most of the parts available at your local Home Depot.

MOXON Antenna Project - The MOXON antenna can provide radio amateurs with an excellent antenna system that is easy to homebrew and usually does not require any adjustment if made according to the dimensions specified by its designer. A typical MOXON rectangle can be built in a few hours, using X type of spreaders arrangement as discussed on this web site.

Moxon equation - Designing moxon rectangles by equation and by model L. B. Cebik, W4RNL

A Portable Multi-Band Magnetic Loop Antenna  ^pop - Described here is a simple multi-band magnetic loop antenna designed for 20, 30 and 40 metres, but by changing the overall length of the wire coverage of other bands is feasible

ARTRA QRP Kits - Lots of homebrew kits, you can buy kits or download as free, Association des Réalisation et Techniques RadioAmateurs. Transceivers, filters, converters, frequency meters, antenna analyzers, ATV receivers, interfaces

PROCOM Antennas - Manufacturer of communications antennas, bandpass filters, RF combiners, receiver multicouplers, diplexers, duplexers, RF connectors, RF circulators, RF isolators, RF couplers and SWR meters

ASTER Teleservices - Telecommunication Infrastructure jobs including the Tower and Foundation design

Timewave manuals - Timewave Documents for User Download, PK-900 Multimode Data Controller, PK-232 Multimode Data Controller, DSP-232 Multimode Data Controller, DSP-9 Noise Reduction and Bandpass Filter, Audio Signal Processor and Noise Reduction Filter, Audio Signal Processor and Noise Reduction Filter for Yaesu SP-5 and SP-6 Speakers

Eurofrequence Dierking in Germany - Accessories, like universal audiofilter, Mixer interface for sound card, highvoltage powersupply, accessories for 706, hamradio vacation,Roger Beep, Microphons, Headsets and more. Please look

ERP Calculator Plus - ERP Calculator is an Amateur Radio software utility designed to perform a side-by-side comparison of two Ham Radio antenna systems. ERP Calculator comes pre-programmed with data files including published data for several popular brands and types of coax cable as well as several popular antenna system brands and models. ERP Calculator displays values of ERP, Antenna Power Gain, Antenna Feed point Power, Antenna System Gain in dB, Antenna Gain in dBd, SWR Attenuation in dB, SWR Power Attenuation, Coax Loss in dB, and Coax Power Loss

AC6LA MoxGen - MoxGen will show you the dimensions and generate an antenna model file for a 50 ohm Moxon Rectangle antenna, given the design frequency and wire size

Spectrum Lab  ^pop - DL4YHF's Audio Spectrum Analyser Spectrum Lab or Speclab started as a simple FFT program running under DOS a long time ago, but it is now a specialized audio analyzer, filter, frequency converter, hum filter, data logger and more. Can be used for MTHELL QRSS, DFCW, PSK, MSK, Castle

MorseGen - MorseGen is a simple program the purpose of which is to generate Morse Code at whatever speed you feel comfortable reading, for practice purposes. It wasn't designed to be a tutor for those who know no Morse at all, although you might find it useful for that purpose. It doesn't have a feature for sending small character groups over and over, although this can easily be achieved by creating text files containing the character groups you want to practice.

Big Fat Tail Productions - PocketSat is a full-featured satellite tracking application for PalmOS and PocketPC devices. It is designed to be usable by both experienced satellite trackers as well as novices who are interested in knowing when they can simply look up and see satellites.

Ferrite information - Ferrite Toroidal Cores, Magnetic Properties of Ferrite Materials, EMI - RFI Suppression Design Considerations, Ferrite Beads, Ferrites for RFI Ferrite Cores for RFI Suppression by CWS ByteMark

80m SSB & CW transceiver - The 80m SSB & CW transceiver design is based on an already proven concept used in ATLAS amateur transistorised transceivers from 70's

144 MHz preamplifier with BF981 - Design of a preamplifier for 144 MHz with 1 dB NF and 23 dB gain using BF981. This amplifier is using a low cost silicon MOSFET (BF981 from Philips) to give more than 20 dB gain with around 1 dB noise figure on 2 meter.

23cm dual stage preamp - A modification / combination of the DJ9 BV & I5TDJ 144 MHz preamp designs

Using ferrites for interference suppression - This tutorial is meant to shed some light on the use of ferrites, and also presents some comparative frequency domain measurements both to illustrate some of the points, and to give designers an idea of what they might expect in using and specifying a ferrite component

TVI filters - These filters are in use by hundreds of VHF weak signal operators and have been proven to be an effective solution for fundamental overload problems.

6m High Pass TVI filter - Are you suffering from TVI? Then why not try this filter for size. It is a three-stage high-pass filter that blocks low-frequency 50MHz signals while letting through UHF TV.

Build A Vector Network Analyzer - The VNA (vector network analyzer) is an essential tool for measuring the complex impedance of a circuit at a given frequency. Article on how to build a Impedance analyzer.