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This Arduino project decode ICOM CAT frequency information and switch antennas according to preset values. RX and TX antennas can even be different, a project by ON7EQ

Great shareware software collection for ham radio, includes prefix finders, locators,frequency generators and links to other ham radio software.

This page provides detailed instructions on building a Lindenblad antenna for 137MHz, including practical details, materials needed, and impedance matching. The author shares their own experience and tips for optimizing performance. The content is useful for amateur radio operators interested in constructing their own antenna for satellite communication on the 137MHz frequency.

A Free windows, universal program for RIG control, can read and set mode and frequency on your transceiver. The program can control ICOM, Yaesu and Kenwood transceivers, by DXSoft

Easy to use Audio Spectrum- and PSK31 decoding program specially designed for SWL's who don't need TX or for anyone who just like to monitor PSK31 or analyse signals. Adjustable DSP and Spectrum settings for audio and frequency spectrum analasys or to set it for best decoding of PSK31 signals. By ON6MU

Design your owm HF shiortened dipole. Includes a diagram of a lumped-constant loaded dipole antenna that is intended to fit in available space, rather than requiring a full 1/2 wavelength, at a specified frequency

US Amateur Radio Band Plans by ARRL

Easy Quad calculator, enter center frequency to get a quad antenna size

A ranking of receiving antennas based on noise being evenly distributed in all directions. These rankings are most accurate in the frequency range of AM broadcast, 160 or 80 meter bands

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

LCF online Calculator, calculate relation between Frequency Capacitance Inductance and Reactance

This document serves as a comprehensive guide for amateur radio operators looking to enhance their Yaesu FT-2000 or FT-950 transceivers with pan-adapter capabilities. A pan-adapter is an invaluable tool that allows operators to visualize the frequency spectrum, making it easier to identify signals and improve operational strategies. The guide details the necessary hardware modifications, including the RF Space IF-2000 board and various SDR options, along with their costs and installation procedures. The document caters to operators of varying technical expertise, providing step-by-step instructions and troubleshooting tips. It emphasizes the importance of using a sound card and software like PowerSDR and HRD for optimal functionality. By implementing these modifications, users can monitor multiple frequencies simultaneously, leading to a more productive and enjoyable amateur radio experience. This resource is particularly beneficial for those looking to modernize their equipment and remain competitive in the ever-evolving world of amateur radio.

A three-frequency multi-band dipole that can be extended easily to additional bands. This article includes a multiband fan-dipole antenna for 80-40-20-10 meter band.

Working with SDR#, adjusting frequency correction and basic setup.

Information about the BDXC and how to join, including a club-compiled list giving time and frequency details for all English language dx and media programmes

General purpose RF Wideband PreAmp based on BSX-20 transistor with a frequency range 14-550 MHz

Design for a very low cost 6-digit frequency counter module using of the shelf components

A page about fascinating Very Low Frequency and natural radio, with lots of streaming audio links from remote receivers. Some experimental stereo pairs around the world.

This simple 30m QRSS beacon is built entirely out of junkbox parts, the only component purchased specifically for this project was the 10,140kHz crystal. Hans Summers' 30m QRSS beacon project emphasizes simplicity and low cost, built almost entirely from reused parts. Key components include a 10,140kHz crystal, a 2N3904 transistor from a broken DVD player, and an ordinary LED used for frequency shift. The oscillator is stabilized in a polystyrene box, with power amplification driven by recycled copper PCB. Output power peaks at 360mW, and a custom 50-ohm dummy load manages heat. Though aesthetically unconventional, the beacon works effectively, fulfilling the project's low cost aim.

Using ferrite to reduce radio frequency interference with your PC monitor or antennas with your receivers or transceivers.

It consists of a radiating wire with a length equal to the half-wave of the fundamental frequency for which the antenna is cut.

Low Cost Frequency Counter, Digital Display and DDS-VFO kits

Power supplies, electrical testers, battery analyzers, cable tester, rf generators, spectrum analyzers, Digital/Analog Oscilloscopes, Multimeters , attenuators, frequency counter

A simple circuit which will generate a 700 Hz tone into any FM transceiver allowing an amateur to practice CW with another amateur on a 2 meter simplex frequency.

AOR USA Web site, manufacturer of base and mobile receivers, handheld receivers, digital voice modems, spectrum display units, frequency monitors and antennas

IC‐2300 MARS/CAP mod expanded frequency range 136‐174 MHz

Pictures, photos, source code and plans to build a logging frequency counter

This receive only loop covers a frequency range of about 5 MHz to 22 MHz and is built from readily available parts.

The Icom IC-7300 is a popular HF transceiver among amateur radio operators, known for its advanced features and performance. This modification guide focuses on enabling extended transmission capabilities, specifically for MARS and CAP frequencies. The instructions are based on the work of PA2DB and include detailed steps for removing specific diodes to unlock additional frequency ranges. Before proceeding with the modification, users are advised to take necessary precautions, such as ensuring the radio is powered off and using ESD protection. The guide emphasizes the importance of using appropriate soldering techniques and tools to avoid damaging sensitive components. A video demonstration is also provided to assist users visually in performing the mod. While this modification can enhance the functionality of the IC-7300, it is crucial to note that it may void the warranty and should be undertaken at the operator's own risk. The guide serves as a valuable resource for those looking to expand their operating capabilities with this versatile transceiver.

Differential Global Positioning Service (DGPS) is a land-based augmentation system that receives and processes signals from orbiting GPS satellites, calculates corrections from known positions and broadcasts these corrections via a Medium Frequency (MF) Transmitter to DGPS users in the Broadcast Site's coverage area.

A windows program that scans the SARK-100 and plot the SWR Vs frequency. The data can also be stored as an Excel file. The min and max match frequency is calculated. Donationware

The problem with making your own trapped HF antennas is usually getting the coaxial traps tuned to frequency.

The website offers a comprehensive guide on high-frequency (HF) skywave propagation for amateur radio operators. It explains HF radio propagation fundamentals, including electromagnetic wave properties, HF bands, and propagation modes like skywave, ground wave, and line-of-sight. The site focuses on the ionosphere's critical role, influenced by solar activity, in refracting HF waves for long-distance communication. Real-time monitoring tools such as DX clusters, beacons, and digital modes like FT8 assist users in tracking band activity and propagation conditions globally. Forecasting methods are detailed, highlighting scientific insights into solar-terrestrial interactions and ionospheric variability. The guide also covers advanced topics like NVIS and gray line propagation, ionosonde data, and propagation prediction models, making it a valuable resource for ham radio enthusiasts aiming to optimize communications

Software to control the frequency and the band on the Kenwood TM-D710.

A 160 meter antenna with a base loading coil used to tune the two lower frequency segments of the band.

Windows remote control for Yaesu or Icom. Displays the current transceiver settings frequency, mode, and others on the PC in an old-fashioned way that corresponds to the look of receivers in 70's. DX-Cluster Watch (DCW) is an application that automatically refreshes a web page with the dx-cluster content, parses spot lines from it, keeps a consolidated list and inserts the spots to VLR as frequency markers by OK1FIG

SignalGen is a free (GPL) Linux (Xwindows GUI-based) utility that generates relatively low frequency signals with the use of a PC sound card. It is an entirely suitable replacement for a hardware signal generator if one doesn't require signals of a frequency higher than about 50 KHz. SignalGen creates any frequency between a fraction of one Hertz and an upper limit determined by your sound card's capabilities.

Online professional-grade high-frequency (3-30 MHz) propagation predictions

glfer is a program for reception and transmission of QRSS/DFCW signals. It is composed of two main parts: the spectrogram window, where you can see the spectrum of the received signal vs. time the transmission functions, to emit cw characters at a slow but precisely controlled speed, using the QRSS (slow CW) or DFCW (Dual Frequency CW) modes

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

An interesting project about an Arduino-based frequency counter fot the Kenwood TS-520S

HF Weather Fax lets you receive marine weather radiofascimile transmissions on your iPad, iPhone and iPod Touch. Just connect it to a shortwave radio tune in a weather fax frequency, and watch the images come in.

Website dedicated to Coastal Radio Stations, includes frequency lists for memdium frequencies maritime stations

This web based application will compute circuit values required for an L-C circuit to resonate at given frequency. Also it will compute the resonant frequency if given values for L and C.

This article presents a technical investigation into spurious emissions from the Yaesu FT-847 transceiver when operating on the 70MHz (4-meter) band. The author discovered significant problems with both factory "UK spec" and modified units. Spectrum analysis revealed that when transmitting at 70.2MHz, the radio produces numerous spurious signals, with the most prominent emission at 45.6MHz measuring only 3dB below the fundamental frequency. The study also documents poor power efficiency on 4m (10.3% at 30W output) compared to 6m operation (23.5% at 30W). Tests verified that jumper configurations had no effect on filter selection. The author warns that using these radios on 4m may violate license conditions due to excessive spurious emissions.

An home-brewed morse code CW filter with a central frequency of 800hz and a variable bandwidth from 230hz to 26hz by F5RDH in french.

United States and Canadian call sign/scanner frequency databases, Worldwide airport frequencies, FIPS codes, Mass Media searches for DXing and more!

Amateur Radio Station owned by Matt Strelow. The station is designed for competition in the multi-operator multi-transmitter category of high-frequency DX contests. Running with 7 towers 6 rotators, 8 beverage listening antennas, and 4 spotting verticals

The Vee Beam antenna project presents a versatile solution for hams, enabling operation across all eight High Frequency bands (80m to 10m) with significant gain on 20m to 10m. This easy-to-construct antenna utilizes two long wires at an angle, enhancing directional performance and minimizing ground losses. With a low visual profile, it is discreet and effective for various applications. The design allows for optimal leg lengths and included angles, ensuring robust performance while maintaining simplicity in construction and operation. The V Beam antenna is an aerial that you can use on all eight High Frequency amateur bands (80, 40, 30, 20, 17, 15, 12 and 10m) with an antenna tuner, and which gives significant gain on the five bands from 20 to 10 meters band.

Leading supplier of low and high frequency electronic filter design products for the design of wireless telecommunications equipment, semiconductors and more