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Mirko Pelcl's extensive radio collection features numerous historical transceivers and receivers, with a significant focus on military communications gear. The collection includes notable examples such as the Wireless Set No. 19, various Cold War-era military radios, and even a rare WWII spy radio utilizing a Loewe 3NF tube. Visitors can explore detailed sections dedicated to sets manufactured before 1945, including those used for military exchange, and a separate category for post-1945 radios, particularly those from the former Yugoslavia. The site also delves into specific modifications, like a digital head conversion for the RU-20, and showcases a frequency counter built with a microcontroller. This personal archive provides a unique glimpse into the evolution of radio technology, from early vacuum tube designs to more modern solid-state military transceivers like the PRC-515. The content reflects Mirko's dedication to preserving and documenting these pieces of radio history.

This resource catalogs a significant collection of historical military radio equipment, detailing various sets from World War II and the Cold War eras. It presents information on British, German, Japanese, USA, and other nations' wireless apparatus, including specific models like the _WS-19_, R1155, and WS-18, alongside clandestine spy equipment. The content covers the preservation and restoration of these historical items, with research results published on the site. The site provides dedicated sections for different national origins of equipment, such as "British sets," "German sets," and "North American sets," allowing for focused exploration of specific military communication technologies. It also features specialized pages on topics like the _Enigma machine_, PARASET builds, and historical events such as Arnhem and D-Day, contextualizing the use of these radios in significant military operations. The collection includes detailed descriptions and images of transmitters, receivers, and associated gear. The museum, located in Kidderminster, Worcs, U.K., organizes physical exhibitions and actively seeks new equipment for its collection, emphasizing its role in preserving military radio history.

Xcorder is a windows Freeware audio recorder written by MM0BFF, designed to work mainly with radio receivers but may be used also in several different ways for audio recording needs.

Details Guglielmo Marconi's foundational contributions to radio communication, highlighting his 1898 Patent **7777** which introduced tuning circuits for independent simultaneous communications. Chronicles the historic transatlantic reception of the Morse code letter 'S' on December 12, 1901, from Poldhu, Cornwall, to St. John's, Newfoundland, a distance of over _3,500 kilometers_. The exhibit showcases early Marconi 10-inch spark transmitters, identical to those used on the _Titanic_, alongside Canadian Marconi crystal detector models. It also features high-end commercial receivers like the IP501, weighing **87 pounds** and originally priced at $595.00, demonstrating the robust construction and technological advancements of the era.

SecondHandRadio.com provides a platform for the amateur radio community to buy, sell, and swap used, surplus, and obsolete electronics and electrical equipment. The site facilitates transactions for a wide range of items, including ham radio transceivers, test equipment, shortwave receivers, antennas, and vintage radio components like tubes. Users can place classified advertisements with photos at no cost, catering to individuals, radio clubs, and commercial dealers seeking to liquidate or acquire gear. The platform emphasizes ease of use with a straightforward sign-up process and no associated fees or commissions for listing or selling items. It positions itself as a primary resource for used electronics within the USA, fostering a direct connection between sellers and buyers without intermediary charges. The service supports various categories beyond amateur radio, extending to military radios and antique equipment, thus serving a broad spectrum of radio enthusiasts and collectors.

The 80 metre fox-or/test transmitter is a small low power transmitter which is designed to be used as an alignment aid for running up 80 metre foxhunt or ARDF receivers. It is also usable as a micro transmitter for fox-or-ing events.

For over 50 years, Communications Specialists Inc. has been a cornerstone in specialized radio frequency solutions, initially gaining prominence with their **CTCSS** and **DTMF** tone signaling products widely used in amateur radio repeaters and commercial two-way radio systems. My own experience with their tone boards in various repeater builds confirms their reliability and ease of integration, a testament to their engineering. The company's legacy in tone encoding and decoding is well-established, providing robust solutions for access control and selective calling. Beyond tone signaling, Com-Spec has diversified into niche markets, including wildlife telemetry, pet tracking collars, and specialized tracking systems for model aircraft and rocketry. Their product line features compact transmitters and receivers designed for specific tracking applications, demonstrating a commitment to precision and durability in challenging environments. While some legacy products are no longer available, Com-Spec continues to innovate, as evidenced by the new R-30M receiver, which ships within five days. This focus on specialized RF applications, from tracking Alzheimer's patients to law enforcement, highlights their unique position in the radio communications industry.

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

Low-frequency (LF) radio time signals, operating primarily in the 40–80 kHz range, are broadcast by national physics laboratories for precise clock synchronization. Transmitters like **JJY** (40 kHz, 50 kW; 60 kHz, 50 kW), RTZ (50 kHz, 10 kW ERP), MSF (60 kHz, 15 kW ERP), WWVB (60 kHz, 50 kW ERP), RBU (66.66 kHz, 10 kW), and DCF77 (77.5 kHz, 50 kW) cover vast geographic areas, often several hundred to thousands of kilometers. LF signals offer distinct propagation advantages over higher-band transmissions such as GPS. Their long wavelengths (3–6 km) enable effective diffraction around obstacles like mountains and buildings. The ionosphere and ground act as a waveguide, eliminating the need for line-of-sight and allowing a single powerful station to cover extensive regions. Ground wave propagation minimizes ionospheric variability effects on transmission delay, and signals penetrate most building walls effectively. Robust and low-cost receivers, often priced at 20–30 USD/EUR, are widely used in radio clocks. These receivers typically comprise a tuned ferrite core antenna, a receiver IC (e.g., Atmel T4227, U4223B, MAS1016) for amplification and AM detection, and a microcontroller for decoding the time signal and phase-locking a local clock. Specific components for DCF77, MSF, and WWVB are readily available from vendors like HKW Elektronik and Ultralink.

An explanation of the different procedures and definitions that are commonly used for blocking dynamic range (BDR) measurements. Dynamic range in general is the ratio between the weakest signal a system can handle and the strongest signal the same system can handle simultaneously without an operator switching attenuators or turning volume potentiometers

The 1 watt 20 meter QRP transmitter with VXO. This is a nice QRP transmitter that can be used in combination of one of the simple receivers.