DIY Antennas, QRP, SDR & Ham Radio Projects from VU3DXR
Decoding the Motorola GM300 model number provides critical details about the radio’s specifications, such as frequency band, power output, channel capacity, and more. The GM300 model number typically follows Motorola’s standard convention, with the first six characters indicating the base model and the subsequent characters specifying features like RF power, frequency range, channel spacing, and […]
The GM300 series radios are line of two-way radios manufactured by Motorola Solutions. They are popular choice for amateur radio operators due to its features, performance, and affordability. GM300 is also a very durable radio. It is built to withstand the elements and can handle even the most demanding conditions. Similarly, the Motorola GM338 is […]
The halfwave end fed antenna is an attractive option for many radio amateurs as it is able to provide multiband operation without the use of traps or stubs whilst occupying a minimum amount of space. A broad-band matching network is typically used to transform the high impedance of the EFHW feed point to 50Ω suitable […]
DIY Programming cable for a Motorola GM 300 series two-way radio To make a DIY programming cable for a Motorola GM300, you will need the following materials: A USB-TTL adapter An RJ45 Ethernet connector A standard silicon signal diode, such as the 1N4148 An Ethernet cable. Once you have gathered your materials, follow these steps […]
VK3YE’s AGC circuit for ubitx An ubitx AGC board is a circuit board that can be installed in a ubitx transceiver to provide automatic gain control (AGC). AGC is a feature that automatically adjusts the gain of the transceiver’s amplifier to maintain a constant audio output level, regardless of the strength of […]
Rothammels Antenna Book For many years, radio amateurs have been using this reference book, which has acquired a firm place in amateur-radio literature as an “antenna cookbook.” Dating back to the fifties, it has developed into a comprehensive reference book for practical use, which has been published in numerous German-language editions. In the interest of […]
This is a Class E Transmitter designed for the 40-meter amateur radio band, capable of producing approximately 4.6W output power at 80% efficiency. Class E Transmitter Power Supply 11.5V DC supply (Vcc) powers the circuit 470µF electrolytic capacitor provides power supply filtering and decoupling Input Stage 1M input resistor provides high impedance input matching 10µH […]
G4RAW 80M QRP CW Transmitter: The original version was built on tag strip, hence the name. For PA, we can use BD139 instead of 2SC2078. It should have good heat sink. The “G4RAW 80M QRP CW Transmitter” refers to a popular, simple, and low-power (QRP) Continuous Wave (CW) transmitter design for the 80-meter amateur radio […]
VK4FUQ’s optimised sloper antenna for 3.5MHz. Radiator and counterpoise radial are both one-quarter-wave in length (length in metres = 71.37/(frequency in MHz) or in feet 234/MHz). The radial should be at least 5ft (preferably about 8ft) above ground and immediately underneath the radiator. Good quality insulators are need at the top of the preferably non-conductive […]
The inverted rhombic antenna boasts a distinctive half-rhombic configuration. Its directivity focuses toward the terminated end, enhancing signal precision. Developed by Bruce, it demands a non-conductive mast for optimal performance. This design delivers significant gain across the 50 to 70MHz bands. A non-inductive terminating resistor is essential, tailored to the RF power delivered. For SSB […]