frequency counter

80 Meter Pizza Pan Antenna - This is a resonant, half-wave, vertical antenna. It takes up little space in the back yard, was designed for operation on a single frequency 80 meter PSK net, and is reasonably inexpensive to construct by Chuck Hines, K6QKL

Horizontal Half-wave Dipole above a Counterpoise - All antennas that are situated close to the ground are affected by that ground to some extent. This article explain effects and benefits of counterpoise.

From Transmitter to Antenna - A collection of articles on the subject of impedance, impedance matching and high-frequency power transmission by G3YNH

Azimuth Radiation Patterns - Below VHF the change in the radiation characteristics of an antenna will change considerably from frequency to frequency, making antenna selection more complicated.

Earth Systems - In order to resonate at a particular frequency, an antenna needs to be at least one half wave length long. Antennas below a 1/2 wave are dependent on a ground system for resonance as well.

SARL Beacon Project on 40 Meters - The beacon project is a South Africa national system of beacons on the 40 meter band operating on a single frequency

VA3GRR - Radio Beacon - VA3GRR is a radio beacon, operating on the 10 meter amateur band. Its frequency is 28.205.5 MHz. It runs just under 5 watts of power into a vertical half-wave ringo style antenna

Italian IOTA List - Italian IOTA Counters (IIA List)

The Considerate Operator's Frequency Guide - A guide to where on the HF bands various modes and activities are generally found. All frequencies are in MHz

Ham Bands - Simplified U.S. frequency allocations table by K8ZT

K9ZW Blog - With Varying Frequency - Amateur Radio Ponderings

Microset - Power supplies, rf power amplifiers, dummy loads, frequency counters, repeaters antennas manufacturer based in Italy

RFS - Radio Frequency Systems (Formerly Celwave, Cellwave, Cablewave),Wifi antennas, duplexers.

FMI - FMI provides superior solutions in the design and manufacture of frequency control devices including Voltage Controlled Temperature Compensated Crystal Oscillators (VCTCXO), voltage controlled crystal oscillator (VCXO), Temperature Compensated Crystal Oscillators (TCXO), crystal clock oscillators, high temperature oscillators, surface mount and crystal oscillator products, phase locked sources and more.

Allocation of Radio Spectrum - This is the table of contents to a list showing how the radio frequency spectrum is allocated to different users in the United States.

New England Historical Radio Society - The New England Historical Radio Society Inc. is an organization dedicated to the preservation of commercial Morse Radiotelegraphy on medium and high frequency.

Radio Frequency Beacon Finder - This project is a radio frequency receiver that will help the user the trace the direction and distance of transmitter beacon(s) operating at 433MHz frequency by Cornell Univerity

Understanding propagation numbers - Quick reference table on understanding A K SFI indexes and how can be translated in usable frequency opportunities

The KA7OEI FT-817 pages - FT-817 Radio Modifications, Improving the FT-817 Noise Blanker, increasing output power, using rechargeable cells, epanding frequency range

Frequenzdatenbank.de - Frequency database for Germany. Emergency services, aircrafts, radio and paging system with over 2000 frequencies from all over Germany.

Suomen taajuuslista 2000 - DB Frequency Site From Finland. In Finnish

Spectrum Analyzer Real-time FFT - Eight-channel Audio Spectrum Analyzer is a set of Real-Time Multi-Channel Gauges for investigation of data accepted from any ADC you will want or 16-, 24- and 32-bit ADC of sound card. WDM drivers support. FFT Spectrum Analysis, OscilloScope, Frequency counter, AC/DC voltmeter, Signal-to-Noise Ratio, Signal-to-Noise and Distortion, Spurious-Free Dynamic Range, Effective Number Of Bits, Total Harmonic Distortion, Inter-Modulation Distortion, Phase Shift. Special modes of dual-channel FFT spectral analysis: Separate channels spectra, Spectra of digital sum, difference, product of two signals, Spectrum of digital product of original signal and its fundamental, Spectrum of Real and Complex Transfer Function, Cross Spectrum. Standart weighing of spectra according IEC and CCIR. Oscilloscope modes (for dual-channel ADC) are: original signals, sum, difference, dependence of one channel on another, amplitude distribution of input signals.

Enable Low Cost RF Power Amplifiers - A new paradigm for low cost, reliable RF amplifier ‘pallets’ has been enabled by new circuit design, manufacturing and thermal management techniques

Legendary microphones for ham radio - Graph of the frequency response of some of the legendary microphones favoured by radio hams

What's a diplexer? - It's a network that splits a signal to two or more loads, dependent on frequency. It is the simplest form of a multiplexer, which can split a signal into many different signal bands.