noise filter

Flags and Pennants - Excellent low-noise receive antennas originated by EA3VY and optimized for 160 meters by K6SE

Receiving loop for long waves - Cancelling out unwanted noise sources by DL3FP

DXCluster IOTA spots - Live IOTA spots by the dxsummit dx cluster

PE1PKU Peter - technics, radio astronomy, great links, duplex filter

K-Com - comprehensive line of products for rejection of Radio Frequency Interference (RFI) to telephone equipment.

Magnecor - Finally auto ignition noise suppressor wires that really work.

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

Kiwa - Filters and performance upgrades for many receivers

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

W2IHY Audio Products - Band audio equalizer and noise gate compatiable with ICOM, KENWOOD, YAESU and other radios

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.

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.

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

WINRLC - Simple freeware tool to calculate several kinds of HF filters. Use to calculate L-C and R-C band filters and bandpasses, L-C, L-R and R-C highpasses and lowpasses, coils and capacitors.

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

DSPFilter - MM Hamsoft  ^pop - Freeware DSP filter by JE3HHT

Spectran - Program designed to do spectral analysis and real-time audio filtering on reception of audio signals for EME, VLF, SETI applications. Offer support for MTHELL, QRSS, DFCW, NDB, WSJT by I2PHD

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

Lowpass filter for 5MHz - The following lowpass filter was built using the tables in the arrl manual, it is a 5 section one and seems to work ok

KI5YN QLF Filter - The QLF filter is a microprocessor based interface designed to go between a standard Morse code key and a radio transmitter

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

7 MHz SSB Transceiver  ^pop - Circuit diagram and discription of 7 MHz Ham Radio SSB Transceiver. Transceiver using two MC1496, 4.43 MHz Ladder filter, LM386, LM324 and IRF840 in final.

Ham Radio Circuits  ^pop - Circuits of SSB Transceiver, AM DSB Transmitter, Antennas, BFO, VFO, 807, FM Mike, Crystal filter and more.

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