frequency

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frequency

533 links - and 9 categories

Antennas : End-Fed : End Fed Half Wave Antenna
  • 40m QRO End Fed Half Wave Antenna Coupler - A medium power End Fed Half Wave Antenna coupler, specifically tuned to the QRP frequency of 7030 kHz. Constructed from coil stock and capacitors, it achieves an impedance ratio of 64:1. The coupler has proven effective for power ranges from 2 to 100 Watts on the 40m band.
    [ Hits: 102 | Votes: 0 | Rating: 0 ]
Antennas : Magnetic Loop
  • Mastering Magnetic Loop Antenna Control - Unveil the secrets of efficient Magnetic Loop Antenna control systems, eliminating the hassle of frequent retuning. With real-time tracking and compatibility with various transceivers, including popular models from Elecraft, ICOM, Kenwood, and Yaesu, this controller ensures seamless frequency adjustment. Explore its high-resolution stepper motor and versatile communication capabilities, revolutionizing amateur radio operation.
    [ Hits: 54 | Votes: 0 | Rating: 0 ]
Antennas : Receiving
  • Chokes and Isolation Transformers for Receiving Antennas  new - Chokes and isolation transformers are essential for receiving antennas to mitigate common mode current, which induces noise and interferes with signal quality. Common mode chokes, formed by winding feedline through ferrite cores, block unwanted current effectively. Proper selection of core material and winding turns ensures resonance near the operating frequency, reducing interference. Isolation transformers further minimize interference, crucial for multi-transmitter stations.
    [ Hits: 52 | Votes: 1 | Rating: 9 ]
Ham Radio : Band Plans
  • Ham Radio Frequencies - This guide explores different radio bands that hobbyists use to talk to each other worldwide. It explains how these bands work and what they're used for. From low-frequency to high-frequency bands, each has its own unique features for people who enjoy communicating through radios
    [ Hits: 72 | Votes: 0 | Rating: 0 ]
Operating Modes : VHF UHF
  • 40 MHz 8m Band Amateur Radio Exploration - The 8m ISM band, a unique frequency range between 10m and 6m, holds potential for amateur radio enthusiasts, yet it remains largely unallocated. This spectrum offers fertile ground for research and self-training. The author's experience with low-power transmissions and WSPR testing highlights the band's capabilities and the need for a narrow, speech-free amateur allocation to encourage experimentation. Discover the world of 8m ISM radio exploration and its future possibilities.
    [ Hits: 72 | Votes: 1 | Rating: 8 ]
Propagation : Beginner's Guide
  • Exploring the Spectrum From HF to UHF Frequencies - During radio's early days, high frequencies were under 30 MHz due to technical limitations. As understanding grew, components improved, allowing for higher frequencies like VHF and UHF up to 3 GHz. The HF band's long wavelengths provide unique propagation challenges influenced by solar activity. VHF and UHF bands face diffraction and reflection issues but offer diverse applications, from amateur radio to 5G and GPS technologies.
    [ Hits: 56 | Votes: 0 | Rating: 0 ]
Propagation : Resources
  • Propagation on 630 Meters and 2200 Meters - This is a theoretical look at propagation on 630-Meters and 2200-Meters using ray tracing software. It expands on the brief discussion in the ARRL Handbooks. The Earth's magnetic field affects 630-Meter and 2200-Meter band propagation. Lower ionization reduces absorption, aiding low-frequency propagation. Differences exist between bands, limited daytime sky-wave propagation. Sunrise/sunset show promise, yet mechanisms are unclear. Ducting possible at night in specific conditions. Negative ions enhance propagation. Inefficient antennas and high man-made noise are anticipated. Groundwave propagation is significant on 2200-Meters.
    [ Hits: 36 | Votes: 1 | Rating: 10 ]
Radio Equipment : HF Transceivers : Icom IC-706
  • Icom 706MK2G Repair  new - After years of reliable performance, a 26-year-old Icom 706MK2G exhibited an unusual deviation during FM transmission, with the actual frequency being 10kHz off from the displayed frequency. Additionally, the power meter showed a sharp dip during transmission. Upon investigation, it was discovered that the FM VCO voltage adjust variable had become dirty and sluggish over time. By adjusting the variable capacitor and cleaning it with switch cleaner, the issue was resolved, restoring stable power output and accurate frequency transmission.
    [ Hits: 15 | Votes: 0 | Rating: 0 ]
Software : Spectrum analyzers
  • Spectrogram - Spectrogram, a PC-based audio frequency spectrum analyzer available from Visualization Software, aids ham radio enthusiasts in aligning receivers like Elecraft K2. Versions are downloadable, with an intuitive interface and customizable parameters. Tutorials by experts like Tom Hammond and John Grebenkemper offer additional guidance.
    [ Hits: 23 | Votes: 0 | Rating: 0 ]
Technical Reference : Arduino
  • Arduino QRP Transceiver: DIY Success on HF Bands - This article introduces an Arduino-based QRP CW Transceiver designed for lower HF bands. The journey begins with the Wotduino, evolving from a keyer to a multi-mode beacon. The development includes a QRP transmitter and culminates in a receiver inspired by Roy Lewallen design. The transceiver, controlled through a control bus features a signal path, modulation, filtering, and adjustable frequency settings. Despite initial testing intentions, successful QSOs on 80 and 40 meters showcase its functional capabilities.
    [ Hits: 104 | Votes: 1 | Rating: 1 ]
Technical Reference : Components : Toroids
  • Measured Data For HF Ferrite Chokes  new - FT-240 toroids measurements. The data was measured using well-calibrated HP instrumentation. All plots have been adjusted to a frequency range of 1-100 MHz on the horizontal axis and a resistance/impedance range of 10-1,000 ohms on the vertical axis. This adjustment facilitates comparison among different materials and aids in determining their suitability for use on the HF ham bands.
    [ Hits: 35 | Votes: 0 | Rating: 0 ]
Technical Reference : Filters
  • Enhancing Frontend Performance with Optimized Band Pass Filters - This article explores the nuanced design challenges of Band Pass Filters (BPF) in radio receivers, balancing low insertion loss, high stop band rejection, and narrow bandwidth. The focus is on the "Series-Trap, Shunt-C" topology, resonator count impact, and meticulous layout design for superior stop band performance across various frequency bands
    [ Hits: 82 | Votes: 0 | Rating: 0 ]
Technical Reference : Radio Frequency Interference
  • Prevention and Suppression of RF Interference to Audio Systems  new - In this study, the author builds upon Muncy's research, demonstrating that radio-frequency current on cable shields affects audio systems through the "pin 1 problem" and shield-current-induced noise (SCIN). An enhanced equivalent circuit for ferrite chokes is proposed, addressing dimensional resonance and inductor self-resonance. Field tests confirm that chokes reduce interference across 500 kHz to 1,000 MHz. Guidelines for diagnosing and mitigating EMI from various sources are provided for product development and field installations.
    [ Hits: 42 | Votes: 0 | Rating: 0 ]

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