History In landline railroad telegraphy, operators traditionally had referred to each other as OM (“old man”). The term YL was coined in 1920 by the American Radio Relay League for young ladies of all ages, as “OM will not fit and … Read More
What is an attenuator? An attenuator is a resistive device that reduces the amplitude of a signal without adding distortion to it. The amplitude of a radio signal is the power, so an attenuator is … Read More
Please consult your national band plan to confirm these frequencies. Some of them may not be within amateur bands in some countries. Analogue SSTV Calling Frequencies 70 cm: (FM) 430.950 MHz SSB SSTV Call Freq. … Read More
Use this page to explain what various functions of a transceiver are and how to use them. Buttons and knobs Ham radio has usually zillions of buttons and knobs and dials on its front panel. … Read More
DTMF Dual Tone Multi-Frequency DTMF is used in ham radio in applications such as IRLP and Echolink, as a means to dial outside numbers via phone patch and as a means for repeater owners to configure the system remotely. It is … Read More
In telecommunications, squelch is a circuit function that acts to suppress the audio (or video) output of a receiver in the absence of a sufficiently strong desired input signal. Squelch is widely used in two-way radios to suppress … Read More
An antenna loading coil is an inductor placed in series with an antenna element in order to lower the antenna’s resonant frequency. A standard dipole antenna is resonant if constructed with a length of one-half wavelength. A vertical antenna (effectively half … Read More
WSPR Weak Signal Propagation Reporter WSPR (usually pronounced “whisper”) is a software application that uses the transmission mode MEPT-JT (Manned Experimental Propagation Transmitter – Joe Taylor). In MEPT transmissions, the radio becomes a beacon that transmits for just under … Read More
Dipoles are one of the first antennas ever created. Indeed, Hertz himself is often credited as the inventor of the dipole, 1886). It’s also the simplest antenna designs out there while staying very powerful and … Read More
A software-defined radio (SDR) is one in which functions such as tuning, filtering and modulating/demodulating are performed by software rather than hardware. The ease with which this is now possible is due largely to advances in digital … Read More