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Noise Canceller kit originally developed about 1989 by G4WMX and GW3DIX and improved by DK9NL and DG0KW.The VK5TM Noise Canceller is another version of the design, with the HF Vox circuit removed and a couple of other minor changes, including the use of SMD JFETs and a double-sided pcb.

Morse code quote of the day

An economical way of building an SSB filter. The circuit is for a filter with a 6 DB band width of roughly 2.2 KHz.

QSL gallery mostly for the deleted countries, old prefix, Antarctic stations and also for the very old cards prior 1945

A forum thread about tuning with the Kenwood TL-922 TL-922A Power amplifier

Mods.dk modifications for the Kenwood TS-690

This project is an APRS iGate for digipeater aboard the ISS. As the ISS pass over the iGate location, the TNC decoded the audio tones and creates data packets the Raspberry Pi can receive.

Forum post on differences between the Acom 1010 (single 4CX800) and Acom 1011 (Two 4CX250B)

Jose B Rivera, N2LRB, shares his initial experiences with the Icom IC-7300, recounting a shift from skepticism to appreciation for the transceiver. He details how the radio's impressive Sherwood Engineering test results, ranking it #12, significantly influenced his decision, especially considering its competitive price point against higher-end options like the Elecraft K3s. The review highlights the IC-7300's strong receive capabilities, a key factor in N2LRB's purchasing decision, and notes the advantages of its SDR architecture for future updates. He describes the straightforward setup process, from unboxing and connecting PowerPole connectors to making a first contact with N0HQ, a special event station. N2LRB expresses satisfaction with the radio's clear audio and ease of tuning, even if the pan-adapter's utility for his operating style remains to be fully explored. He concludes that the IC-7300 offers exceptional value, providing SDR features and receive performance comparable to more expensive rigs at half the cost.

Test equipment and ham radio related manuals

A facebook group where all women and girls in ham radio can gather together to share the common interest of amateur radio.

A 600 volts power supply for QRO

Baofeng UV-5R uses RS232 to communicate or programming with the PC software and you can make your own programming cable with a few components.

Programming memories manually the Baofeng UV-5R

Demonstrates the fundamental principles for connecting a personal computer to a ham radio transceiver, specifically for utilizing sound card-based digital mode software like those in the MM Hamsoft suite. It details the basic hardware setup, emphasizing the use of shielded leads and proper audio routing from the radio's output to the sound card's input, and from the sound card's output to the radio's microphone or data input. The resource highlights the critical need for transmit attenuation, suggesting a 100:1 voltage divider to prevent overdriving the transmitter's audio stage, and mentions the optional addition of ferrite beads and decoupling capacitors for RFI mitigation. The guide also points to external resources for more detailed pin-outs and interface schematics, such as a specific QSL.net page, and recommends consulting the help files within MM Hamsoft programs for interfacing specifics. It underscores that while the process is straightforward, understanding the audio level management and proper cabling is key to successful operation. The author, VE5KC, provides practical advice drawn from common issues encountered by operators setting up digital mode stations.

A cavity filter, often a critical component in _duplexer_ designs, functions as a sharply tuned resonant circuit, allowing only specific frequencies to pass while attenuating others. These filters are essential for maintaining signal integrity in environments where multiple transmitters and receivers operate simultaneously on closely spaced frequencies, such as in repeater stations. The article details how these filters, sometimes referred to as _notch filters_, achieve high Q factors, which are crucial for their performance. Understanding the principles of cavity filters is fundamental for any amateur radio operator involved in repeater operation or designing custom RF front-ends. The discussion covers the basic circuitry and operational characteristics that enable these devices to provide significant isolation, often achieving **-80 dB** or more between transmit and receive paths. This level of isolation is vital for preventing receiver desensitization and intermodulation distortion. Properly tuned cavity filters ensure that a repeater can transmit and receive simultaneously on different frequencies without self-interference, a common challenge in VHF/UHF operations.

How much better is an N over SO-239 at VHF/UHF, a discussion topic at eham

Distributed Antenna Systems technology used for gaining better coverage and using a lower power.

Gridmaker takes your ADIF-file and searches for all the grids on the specified band. It then makes files for use in DXAtlas

Ham radio classifieds in Austria

Articles about TM-D710 radio modifications at Mods.dk

Smart antennas or the adaptive antenna array and smart antenna technology used with SDR, cognitive radio, MIMO, and other new technologies.

Online Constant - k Lowpass Filter calculator

A portable decoder for METEOR M weather satellite LRPT signal, available for windows and Linux

This is a popular discussion forum for ham radio operators

ICNIRPcalc allows you to calculate safety distances for many know amateur radio antennas with respect to ICNIRP limits by DL9KCE

Butterworth Highpass Filter Designer

A summary, overview or tutorial covering the basics of Meteor Scatter or Meteor Burst Communications, a form of radio signal propagation often used at VHF.

Near Vertical Incidence Skywave propagation is a form of radio wave propagation used on the MF and HF bands to provide radio communications and broadcasting coverage over short distances, especially where the terrain contains obstacles.

Article on Yagi and Log periodic antennas by Tom, K1JJ

The basics of radio receiver dynamic range performance used for specifying the performance of radio receivers used in radio communications systems.

An overview of the development of the Morse key for sending the Morse Code, from the first camelback keys, through straight keys and sideswiper keys to the semi automatic keyers including the Vibroplex to the modern electronic keyer.

T30AQ Online Log Search

Article on antenna feed impedance and the importance of matching RF andtennas to feeders, including notes on Radiation resistance, loss resistance, and efficiency are also detailed.

Upload an ADIF fiel and plot all worked grids in an online map. Support filtering by band, year and can export the output directly into a google map, or a google earth KML file

About antenna or aerial resonance and bandwidth and the impact of RF antenna resonance and bandwidth on radio communications systems.

STØR Souther Sudan dx pedition july 2011

Articles and review on the Yaesu FT 817 by OZ9AEC

A linear regulated power supply 2A, 20 V designed mainly to get used to soldering and have something usefull as final result.

UV5R / UV82 series UV5R, UV82, GT3, BFF8, F8HP, etc Keypad Layout and Functions

Introduction to shortwave propagation

The details of the spark gap transmitter and its history: how it was invented, developed and used.

Article on propagation basics. The ground wave used for radio communications signal propagation on the long, and medium wave bands for local radio communications

The _Touch CPO_ circuit offers a unique method for Morse Code practice, eliminating the need for a physical key. It leverages the versatile IC555 timer, configured as an astable multivibrator, to generate an audio tone. Users can adjust the tone's frequency by manipulating a 100 K variable resistor connected between pins 7 and 6 of the IC555, providing flexibility in the practice experience. Volume control is achieved via a 10 K variable resistor, while a 1 K Ohms preset at pin 4 of the IC555 allows for fine-tuning the touch plate's sensitivity. The design connects the touch plate to the base of a BC147B transistor, a configuration noted for its flexibility regarding the length of wire between the transistor and the touch plate. The author's prototype successfully used a 9 cm wire with a 3 x 6 cm aluminum plate. This project also suggests an alternative application as a touch-operated doorbell, demonstrating the circuit's adaptability. The design emphasizes simplicity and ease of construction, making it accessible for hams interested in DIY electronics.

The low band, VHF, UHF and microwave chats

A short introduction to amateur radio portable operations bu VKFAQ.

All the essentials about the Dip Meter or Grid Dip Oscillator used for many RF measurements including detecting resonance, locating RF emissions, and making many RF measurements.

overview of radio signals and radiowave propagation and how different areas of the atmosphere affect radio communications.

Dopller effects on satellite tracking