low pass audio filter

Harlow & District Amateur Radio Society - Local radio club for Harlow in Essex, England

Manchester amateur radio club - Teaching the RAE with lots of info to help you pass the test For CW, Novice, RAE,.

Ham Radio Community Chapter Priority listing - Ham radio webcam live, solar updates, radio mods, satellite images, audio and video interactive, polls, links, constant events, weather, qrz database, by kd4sai

Virtual Tuner - VirtualTuner.com is a free service that allows you to search through our database of thousands of streaming media and radio sites.

Gisela Dierking NF/HF-Technik Germany - Many interessting accessories, like unversal audiofilter, Mixer interface for sound card, highvoltage powersupply,accessories for 706, hamradio vacation, and more

Industrial Communication Engineers - RF parts, filters, rf switching products.

Nally radio towers - Radio towers with designs made specificaly for Amateur Radio operators, incorporating mounting plates for most common rotators with in tower structure allowing for safety in the use,and tilt over preventing the need for climbing towers during regular maintance

Hellschreiber beacon project - This web site describes a low power beacon system to be used for propagation and performance tests on the lower bands. The beacon offers CW (on-off keyed) modes and FSK modes; the traditional Morse ID mode, and Feld-Hell, another highly noise immune CW mode.

Yaesu 920 & SoundCard - This circuit provides an interface between the Yaesu 920 transceiver and IBM computer sound card which allows data transfer and control of PSK31, RTTY, KEYBOARD CW, and SSTV modes for Amateur Radio

Sunspot activity by NASA - Sunspot cycle closely following prediction by Science @ Nasa

Scanrec Scanner Recorder - Scanner Recorder (Scanrec) is a free audio recorder that is primarily designed to record speech. It has a VOX control that allows the user to save disk space when no sound is present in the signal. Since FM communications has such an effective squelch, the recorder works best with FM. HF ham bands and World Band radio have such a poor signal to noise ratio that the VOX gate on Scanrec might not be very easy to set.

Vox Recorder  ^pop - Vox Recorder is a Windows utility wich allows recording sound from an audio source only when an audio signal is present; its main purpose is to avoid the recording of the silence eventually present at the input. Vox Recorder has been designed in particular for radio-scanner hobbists.

QSO Manager - HF QSO/QSL/Award managment, ADIF Import/Export, full version free to everybody. Requires Access 97 or Access 2000 (with JPEG and TIFF filter installed), screen resolution 800x600/1024x768

BeaconSee - BeaconSee shows you, in real time, worldwide HF band openings on your PC. Analyses the audio signals from your radio, which is tuned to the NCDXF IARU HF beacon network and shows you the signal strength received from each of the 18 beacon transmitters as a plot of frequency spectrum against time.

Free programmable DSP-Filter  ^pop - Free programmable LOW/HIGH/BANDPASS FIR filter in the audio range 0-4kHz

Voice Descramble - This program descrambles band inverted encrypted transmissions, usually found on VHF/UHF. It uses a NCO (numerical controlled oscillator) to re-produce the originally inverted audio band.

RemIcom-B - Freeware RemIcom-B is a very simple ICOM remote program. Display of current frequency, mode and filter ITU HF Band assignment (ITU Region 1, 2 and 3 selectable) HAM HF Band usage analog frequency band display

SSTV1 - SSTV1 Modem software is an AFM modem that runs on the TAPR/AMSAT DSP-93 hardware platform that can be used to receive and transmit Slow Scan Television(SSTV) signals.

Spectra - Accurate spectrum analyzer in the range 0 - 2500 Hz, makes an accurate FFT analysis of an audio signal coming from the soundcard

Vox Actuated Recorder for Windows - Vox Recorder is a Windows utility wich allows recording sound from an audio source only when an audio signal is present; its main purpose is to avoid the recording of the silence eventually present at the input.

Next generation beacon - The next generation beacon platform for the OZ7IGY beacons should encompass both the analog and digital mode, i.e. FSK and MGM in a mixed mode configuration

SSB and CW Filter - A pdf file with schematics of an ssb and cw filter AF amplifier

Mode J Desense Filter - 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

Toroid Pro - Designed by microwave engineers to provide filter, radio,microwave and Ham radio engineers with all relevant information of an inductor and core at his or her finger tips

Homebrew radio receiver  ^pop - Detailed plans of my homebrew receiver. Frequency coverage is from below 300kHz to 30MHz. Pictures, schematics, board layouts, parts lists and more can be found here.