hi tech

235 links

160 meter antenna problems and solutions - The quarter-wave Marconi working against ground is a popular and inexpensive antenna for 160 meters. A lot of newcomers to the band favor this simple antenna because it's easy to put up, it isn't too big, and it works.
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20 meter short loaded vertical antennas - Loading is a way to lower the resonant frequency of an antenna radiator. This technique is typically used in antennas that have radiating elements that are too short for the desired resonance frequency. In this excellent article the author experiment loaded vertical dipoles for 20 meters band
[ Hits: 232 | Votes: 1 | Rating: 9 ]

An 8x2 Element Array Antenna For 144 MHz - This stacking offers a well known simple phasing technique. All elements can be fed in parallel by open wires provided that they are fed in phase. This can be achieved by twisting the open wire phasing-lines at 180 degrees.
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The Story of the Broadband Dipole - A dipole can be broadbanded by a number of techniques including by matching with resonant sections of transmission feed lines.
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Patented RF choke test - A reproduction test of a a binocular ferrite core and winds a total of 7 turns is a patented rf choke with an unusual winding, although this winding scheme reduces the inductance, it might result in a much larger bandwidth over which the choke has a sufficiently large impedance. The Author test this model by reproducing the choke.
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Drive-On Antenna Mast For POTA - This antenna mast mount uses two Reese hitch extensions that are welded on to a piece of 2 inch square tube. It comes apart in two pieces. The vertical pipe on the left is welded on to a 2 inch piece of square tube that fits into the Reese hitch extension.
[ Hits: 156 | Votes: 1 | Rating: 9 ]

Which part of a dipole radiates most? - The title may seem a strange question. Still, it is often said that the part where the current is largest, radiates most. And from that a rule of thumb follows, saying that if you don't have enough space to hang a complete half-wave wire dipole then try to make the central part hang as freely as possible.
[ Hits: 157 | Votes: 1 | Rating: 9 ]

A Versatile SOTA Antenna Tuner - This is a detailed, technical piece, intended mostly for makers and more creative activators, who enjoy building and using their own tools on the summits. A multiband portable antenna tuner supporting 10W, small and light, suitable for SOTA operations
[ Hits: 265 | Votes: 2 | Rating: 10 ]

Pikes Peak Radio Amateur Association (PPRAA) - The Pikes Peak Radio Amateur Association (PPRAA) is an American Radio Relay League (ARRL) Special Service Club located in Colorado Springs, Colorado. The PPRAA is a social and technical membership organization which provides educational and recreational activities for its members intended to further their knowledge in the art of radio communications.
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Radio Scouting K2BSA - Radio Scouting is the intersection of Scouting and amateur radio. As such it introduces Scouts to the fun, technology and magic of amateur radio. It does this through the power of the world’s largest Scouting event, Jamboree on the Air, with over 700,000 Scouts engaged in connecting with one another through amateur radio the third weekend of October.
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History of the Radio - The history of the radio is a fascinating one that changed how the world connected and communicated from distances both far and near. History of the Radio from Inception to Modern Day
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Portable Operating Tips for Ham Radios - This article is from the book Ham Radio For Dummies and features some tips for portable amateur radio operations, on Field Day or generic outdoor operation, like selecting the proper antenna and portable power.
[ Hits: 79 | Votes: 1 | Rating: 10 ]

Elecraft K4 Transceiver - Official Elecraft K4 Transceiver page at Elecraft web site with technical specifications, news, manuals and software updates for the K4, HF High performance direct sampling SDR Radio transceiver by Elecraft
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VARA - VARA HF is a soundcard modem that can be found on the HF bands exchanging traffic (Winlink). VARA implements an High Speed Data Mode and comes in 2 separate programs VARA FM and VARA HF. VARA is a High Performance HF modem based on OFDM modulation. VARA Modem, brings state of the art Military grade technology to new and existing HF data. Introduces a new standard of technology available for Amateur and Commercial use. Designed for operation within a SSB Bandwidth of 2400 Hz.
[ Hits: 105 | Votes: 1 | Rating: 10 ]

A Morse Code Practice Oscillator - Maybe not state-of-the-art technology but the author offers a quick and easy project for a Morse code practice oscillator using a 555 timer chip
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Morse Code Practice Oscillator - In this project, we blend old school and new school tech to create a Morse code oscillator that you can use to practice keying Morse code. We start by milling out a double-sided board on the Bantam Tools Desktop PCB Milling Machine, then we solder on a series of components, and finally test our skills of yesteryear communication
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Demonstrating AM sidebands - Amateur radio courses teach that in amplitude modulation, sidebands arise. This can be proven mathematically, and nowadays with an SDR one can easily see them.
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Understanding computer-generated RFI - Radio Frequency Interference (RFI) has always been a source of concern for the Radio Amateur. Until the recent introduction of complex circuitry in the home, our communications gear has been the main source of potential RFI. In this computerized age of ours, increasingly complex and sensitive receivers are being barraged by these and other sources of RFI.
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Stop RFI from Solar PV Systems - Stop EMI RFI Interference in Off Grid Solar PV Systems, in this article the author provides hints on tracking down the EMI or RFI source, shielding and grounding in order to eliminate interferences on the whole HF and VHF ham radio bands
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A Simple Hybrid Software Defined Radio - This Hybrid SDR is a combination of a current technology analog radio techniques, used with a direct conversion software defined radio to create a single conversion "hybrid" radio that is usable over a wide range of frequencies
[ Hits: 115 | Votes: 0 | Rating: 0 ]