One question. One answer. Zero noise.
DMR uses two time slots on one 12.5 kHz radio channel, allowing two separate digital voice conversations to share the same RF channel.
On-the-air test transmissions must identify the transmitting station.
FCC compliance can be demonstrated by accepted calculations, computer modeling, or calibrated field-strength measurements.
A diode conducts readily in its forward direction and blocks current in the reverse direction under normal operation.
Selectivity is a receiver's ability to separate the desired signal from other signals on nearby frequencies.
To measure current, the meter must become part of the current path so the same current flows through the meter and the component.
When calling a specific station through a repeater, say that station’s call sign first and then give your own call sign so everyone knows who is calling whom.
Coaxial feed-line loss can increase because of water intrusion, mismatch-related current and voltage effects from high SWR, and additional connector losses.
If the FCC cannot reach you by email, the station license may be revoked or the operator license may be suspended.
A potentiometer is a variable resistor with an adjustable contact. Audio volume controls commonly use it to vary the signal level.
Antenna gain describes how strongly an antenna concentrates radiation in a specified direction compared with a reference antenna.
LEO means Low Earth Orbit. Many amateur satellites in LEO circle Earth in roughly 100 minutes.
Ionospheric propagation can change a signal into elliptical polarization, so the arriving wave is not purely vertical or horizontal. Either antenna orientation can therefore receive some of the signal.
If the amateur transmitter is operating properly but a nearby broadcast receiver is overloaded, filtering at that receiver's antenna input can reject the amateur signal before it reaches the receiver circuitry.
Water changes the electrical properties of coaxial dielectric material and can corrode conductors. Moisture contamination is therefore a common cause of coax failure.
Use I = E ÷ R. Dividing 120 volts by 80 ohms gives 1.5 amperes.
Amateur radio is explicitly intended to develop technical and communication skill, not simply provide another personal communications service.
The Net Control Station manages the flow of a directed net by opening the net and directing communications among stations that check in.
The standard abbreviation for kilohertz uses a lowercase k, uppercase H, and lowercase z: kHz.
High charge or discharge rates can create damaging heat and may cause gases to be released, depending on battery chemistry and condition.
Use R = E ÷ I. Dividing 90 volts by 3 amperes gives 30 ohms.
Auroral backscatter reflects VHF signals from disturbed regions near the aurora. The rapidly changing path produces a distinctive rough or raspy sound.
A transformer transfers AC energy magnetically between windings. A step-down transformer can convert 120 volts AC to a lower AC voltage.
Phonetics improve intelligibility when voice conditions are difficult, but the rules do not make a particular phonetic alphabet mandatory for ordinary identification.