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A very simple experimental short wave radio receiver. This is basically just a crystal radio with two stages of transistor amplification afterwards made with scrap components.

Receivers and transmitters by Collins , Drake , Hallicrafters , Hammarlund , National Receivers

Barest of bones APRS RF position reporter using a Raspberry Pi B+, USB GPS receiver, Baofeng UV-5R, and a mono 3.5mm audio cable between the Pi and the radio

Technical details of the Drake R-4C receiver

KiwiSDR Software-defined receiver at Bjargtangar Iceland covering HF Bands

Vintage radio and scientific apparatus by john jenkins, include antique radios, Horn Loudspeakers, Vacuum Tubes, A.C. Receivers

How to build a complete Single-Sideband amateur radio transceiver from scratch. Article published on hackaday dot com includes an introduction to radio architectures, ssb receivers and tramsitter

FHD22 radio-relay transmitter and receiver by F4DAY

Key details about the superhet or superheterodyne radio reeiver: basic overview; how it works; applications; design notes, all you need to know.

Since 2011, crkits offer radio kits that you cannot find on eBay or AliExpress. Includes HT-1A 20/40m Dual Band CW Transceiver Kit, D4D DSB Transceiver Kit for Digital Mode, R3500D ARDF Receiver, CW Transceiver Kit

N-channel scalable coherent receiver that employs the RTL-SDR technology in order to create inexpensive multi-channel receiving systems.

This FM wireless mike can transmit voice signals to any FM Radio receiver 100 meters away.

Presented is a historical collection of short-wave listening (SWL) QSL cards, primarily from the late 1930s and early 1940s, offering a glimpse into early international broadcasting and the technical pursuits of SWL operators like Les Miles during that era. The resource showcases specific QSLs from stations such as _Broadcasting Corporation of Japan_, _XGOY - The Central Broadcasting Administration_ in Chungking, China, and _Australian broadcasting ship, Kanimbla VK9MI_, each with reception dates and frequencies like 11.90MHz or 9.525MHz. It highlights the self-sufficiency of SWL enthusiasts who constructed and maintained their own radio and test equipment, evoking the sensory experience of vintage valve receivers. The collection provides concrete examples of international broadcast stations active before and during World War II, including _2RO3 - Rome_ and _WRUL - World Wide Broadcasting Foundation_ from Boston. Each QSL entry details the station, location, reception date, and often the frequency, such as 9.63MHz or 11.26MHz, allowing for historical verification of broadcast schedules. The resource also briefly mentions the operational details of the _VK9MI_ offshore radio station, directing readers to further information on its history. This compilation serves as a tangible record of global radio communication during a pivotal historical period.

A 0-30 MHz step attenuator, constructed from switchable Pi attenuation pads, provides a practical tool for evaluating receiver sensitivity and calibrating S-meters. The design utilizes readily available 5% tolerance resistors, with values derived from paralleled components to achieve specific attenuation steps. A schematic (Fig 1) illustrates the circuit, including PCB pad shielding, while a table details required and actual resistor values, along with percentage differences. Measurements of voltage input versus output at various frequencies are used to calculate dB attenuation, presented in a graph (Fig 4). The resource includes formulas for determining output voltage from a known input and a comprehensive 0-40 dB voltage multiplier table, which is crucial for precise signal level management. The project also references external attenuator calculators and equations for further study. Photos (1-3) provide visual guidance for the assembled unit, showing bottom, top, and front views. The project emphasizes the use of **Pi attenuation pads** and **receiver sensitivity** evaluation, offering a hands-on approach to RF signal management.

The ICOM IC-R72E a neat compact communications receiver. Coverage: LW, MW, SW (0.1- 30.0 MHz continuous) discontinued in 1998

Drake R-4 Receiver manual

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.

Amateur Packet Reporting System (APRS) operations often require compact, reliable solutions for transmitting position data, particularly for mobile or portable stations. This resource details the construction of the _Tiny Track-I_, a transmit-only APRS tracker designed for straightforward integration with a VHF radio and a Global Positioning System (GPS) receiver. It enables hams to broadcast their location without the complexity of a full-duplex TNC. The project outlines the printed circuit board (PCB) layout and schematic, based on an original design by N6BG, with a personal PCB drawing by SV1BSX. It includes specific component placement and notes an additional 10uF/10V capacitor (C5) for improved IC voltage decoupling, a modification not present in the original N6BG diagram. The unit connects to a computer or GPS via a DB9 female connector. This tracker is ideal for basic position reporting, offering a simple and effective way to participate in APRS networks. Its small footprint makes it suitable for vehicle installations or field deployments where space is limited, providing a **reliable 9600 baud** data stream for location updates.

A complete review of the Ten-Tec RX340 all mode HF receiver

Gimme Five reloaded, a compact 5 band QRP SSB transceiver in SMD technology. This unit covers 5 bands within the amateur radio spectrum (3.5, 7, 14, 21 and 28 MHz). Receiver is a single conversion unit with an interfrequency of 9 MHz. Transmitter uses 5 stages and has got a power level of 10 watts PEP output.

Sending the Audio from the Receiver to the Recorder, from the Recorder to the EQ, and sending the Audio from the EQ or Recorder to the Transmitter

A review of the Chinese version of uSDX USDR HF QRP Transceiver. Author made an extensive review of receiver and transmitter features.

A detailed review of the Icom IC-R75 30 kHz -6 0 MHz Receiver first introduced in 1999

VHF-UHF receiver covers from 25 to 800 and 900 to 2000 MHz in the following modes: AM, AM-W, FM, FM-W, FM-N, USB and LSB

If your 756 has lots of noise with crackles and sweeping heterodynes, especially noticeable on AM, it may be due to a faulty electrolytic capacitor in the noise-blanker circuit

Homebrew Antennas, Transmitters, Receivers, Converters, Keyers and SWR/RF Current Indicators with photographs an excellent blog with many projects by VU2NAN

Manufacturer of software definded radio receivers, antenna switches, preselectors, antenna splitters based in Italy and USA

Homemade receiver for 80 meters band. The receiver works very well (in fact better than some of its successors), especially the AGC makes listening to 80m QSOs a real pleasure. Sensitivity is not cutting-edge, but on a full-size short-wave antenna it is by fare sensitive enough.

Operating in a Single Operator Two Radios (SO2R) setup, especially with beverage antennas, often exposes the receiving radio's front-end to significant RF energy from the transmitting radio. This resource details a practical, homebrew receiver protection circuit designed to mitigate this risk. The core of the design involves a non-inductive 2W 22 Ohm carbon composition resistor in series with the RX antenna line, followed by two stacks of four fast-switching diodes (e.g., _1N914_) configured in opposite polarizations. This arrangement effectively clamps the incoming voltage to approximately 2.8 V peak-to-peak, safeguarding sensitive receiver input components. The series resistor plays a crucial role by absorbing excess power, preventing the diodes from exceeding their current ratings and potentially failing open, which would leave the receiver unprotected. The author, _N4KG_, measured up to 50 watts of coupled power between 80M slopers on the same tower, highlighting the necessity of such protection. The design is presented as a cost-effective solution to prevent damage to receiver input transformers, with the author noting successful protection of a receiver even after a resistor showed signs of overheating. This simple circuit can be integrated via a transverter plug, offering a robust defense against high RF input.

This is a compact three transistor regenerative general coverage receiver with fixed feedback. The sensitivity and selectivity is relative good, especially on the LF and MW bands, as can be expected with this simple design.

Crystal receivers are radio receivers that work without a power supply or batteries. Gallery of some crystal radio projects

Stand Alone Software Defined Radio, direct sampling receiver from 30 kHz to 1700.00MHz continuous frequency range, LAN interface for remote access

How to modify your scanner or receiver with a discriminator output. If you want to decode and monitor digital (FSK and PSK) systems seriously, a discriminator tap is an absolute prerequisite.

This is a WebSDR receiver, located in Friedrichshafen, Germany (at Lake Constance) using a multiband dipol and a FUNCube Dongle Pro+.

An independent review of the Grundig Yacht Boy 360 portable mediumwave receiver

eHam users review of the Icom IC-R75 receiver

Filters and replacement parts for the Drake R-4C receiver by Sherwood Engineering Inc

eHam.net reviews of the Icom IC-R20 wideband receiver

WebSDR receiver located near Krizevci, Croatia with 0-2 MHz, 60-80 meters band and 40-49 meters band

eHam reviews of the Icom IC R7100 VHF UHF receiver

The build was an experiment to see if a tube receiver could be stable enough to receive digital shortwave radio broadcasts. The tube acts as both an oscillator and mixer, so the receiver is a type of direct conversion receiver.

A very small receiver converter that can be plugged to the backside of the battery powered portable transceiver FT817 from Yaesu. A high performance receiver for 2.3GHz amateur radio signal

A software defined receiver located in Tuscany Italy with a Windom antenna convering HF bands

Tutorial- WSPR receiver with Raspberry Pi and RTL-SDR

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

If You are using a separate receive antennas then you need a good protection circuit to eliminate the possibility of blowing out the receiver front-end while using these auxiliary receive antennas specially on low bands.

I have RFI, now what– Locating it. This article is the first of a three parts article, that covers the problem of locating the RFI source. Author make use of an SDR receiver to locate RFI emissions. Ai interesting RFI location process diagrams helps on following the various phases, permitting the discovery of almost 75% of the RFI issues.

The MiniTioune receiver project, developed by Jean-Pierre F6DZP, consists of the home constructed MiniTiouner hardware which interfaces via a standard USB 2.0 port to a Windows PC running the MiniTioune software. It can be used to receive satellite broadcasts transmissions making it ideal for use on Q-oscar 100 Es hail-2 without any external frequency converters.

List of global weather fax (HF fax) stations, including their locations, call signs, and frequencies. Click on any station's call sign to view its weatherfax broadcast schedule. This site provides various radiofax receiver manuals in PDF format, on the Receivers page.

Super Simple APRS Position Reporter. This project idea has been in response to the more hardware heavy Raspberry Pi projects that involve extra TNC hardware, additional sound cards, and custom cabling. This APRS position reporter is done using a Raspberry Pi B+, USB GPS receiver, Baofeng UV-5R, and a mono 3.5mm audio cable between the Pi and HT.