One question. One answer. Zero noise.
Interference can result from direct overload by the desired transmitter frequency, from harmonics, or from other unwanted spurious emissions.
Use E = I × R. Two amperes through 10 ohms produces a voltage drop of 20 volts.
Current through the body can injure in several ways at once: it can heat tissue, interfere with normal electrical activity in cells, and trigger involuntary muscle contractions.
Any licensed amateur may select a desired call sign under the vanity call sign rules.
Use P = E × I. Multiplying 12 volts by 2.5 amperes gives 30 watts.
Radio-wave polarization is defined by the orientation of its electric field. A vertically polarized wave has a vertical electric field; a horizontally polarized wave has a horizontal one.
146.520 MHz is the nationally recognized 2-meter FM simplex calling frequency.
A digital-mode hotspot acts as a local RF gateway. A nearby handheld or mobile radio talks to the hotspot, which then links that traffic into an internet-connected digital voice or data network.
The standard abbreviation for megahertz uses uppercase M and H with lowercase z: MHz.
EchoLink requires users to register their amateur call sign and verify that they hold a valid amateur radio license.
A typical VHF FM repeater voice signal occupies roughly 10 to 15 kHz, considerably wider than an SSB voice signal.
PSK stands for Phase Shift Keying, a digital modulation method that conveys data by changing the phase of the carrier.
Use E = I × R. Multiplying 0.5 ampere by 2 ohms gives 1 volt.
One kilohertz is 1000 hertz. Dividing 1,500,000 hertz by 1000 gives 1500 kilohertz.
A transistor can control a larger output signal using a smaller input signal, which lets it provide amplification and power gain.
An energized antenna can develop RF voltage and current high enough to heat tissue at the point of contact, producing an RF burn.
An inductor and capacitor exchange energy between magnetic and electric fields. Together they form an LC resonant or tuned circuit.
When an ohmmeter is connected across a large discharged capacitor, the meter initially supplies charging current. As the capacitor charges, current falls and the indicated resistance rises.
Schematics are designed to show electrical connections and circuit relationships. They do not normally preserve real wire lengths or the physical appearance of components.
The ionosphere contains charged particles that can refract or return HF signals toward Earth, allowing contacts well beyond the normal line-of-sight range.
Component 6 in figure T-2 is the capacitor symbol, represented by two opposing conductive plates.
Moving an antenna can increase the distance between people and strong RF fields or redirect the field away from occupied areas.
A half-wave dipole has its strongest radiation broadside to the wire and much weaker radiation off the ends.
After the exam, the official notice of your new license and call sign comes by email from the FCC with a link to the license grant.