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Offset
The 300 to 1000-Hz difference in CW transmitting and receiving frequencies in a transceiver. For a repeater, offset refers to the difference between its transmitting and receiving frequencies.

Ohm
The basic unit of electrical resistance, used to describe the amount of opposition to current.

Ohm's Law
A basic law of electronics. Ohm's Law gives a relationship between voltage (E), current (I) and resistance (R). The voltage applied to a circuit is equal to the current through the circuit times the resistance of the circuit (E = IR).

One-way communications
Transmissions that are not intended to be answered. The FCC strictly limits the types of one-way communications allowed on the amateur bands.

Open circuit
An electrical circuit that does not have a complete path, so current can't flow through the circuit.

Open repeater
A repeater that can be used by all hams who have a license that authorizes operation on the repeater frequencies.

Operator/primary station license
An amateur license actually includes two licenses in one. The operator license is that portion of an Amateur Radio license that gives permission to operate an amateur station. The primary station license is that portion of an Amateur Radio license that authorizes an amateur station at a specific location. The station license also lists the call sign of that station.

Output frequency
A repeater's transmitting frequency. To use a repeater, transmit on the input frequency and receive on the output frequency.

Packet radio
A system of digital communication whereby information is broken into short bursts. The bursts ("packets") also contain addressing and error-detection information.

Parallel circuit
An electrical circuit in which the electrons follow more than one path in going from the negative supply terminal to the positive terminal.

Parasitic beam antenna
Another name for the beam antenna.

Parasitic element
Part of a directive antenna that derives energy from mutual coupling with the driven element. Parasitic elements are not connected directly to the feed line.

Peak envelope power (PEP)
The average power of a signal at its largest amplitude peak.

Pecuniary
Payment of any type, whether money or other goods. Amateurs may not operate their stations in return for any type of payment.

Phone
Another name for voice communications.

Phone emission
The FCC name for voice or other sound transmissions.

Phonetic alphabet
Standard words used on voice modes to make it easier to understand letters of the alphabet, such as those in call signs. The call sign KA6LMN stated phonetically is Kilo Alfa Six Lima Mike November.

Pico
The metric prefix for 10 - 12, or divide by 1,000,000,000,000. PL (see CTCSS)

PL
(Also known as CTCSS - Continuous Tone-Coded Squelch System) A sub-audible tone system used on some repeaters. When added to a carrier, a CTCSS tone allows a receiver to accept a signal.

PNP transistor
A transistor that has a layer of N-type semiconductor material sandwiched between layers of P-type semiconductor material.

Polarization
The electrical-field characteristic of a radio wave. An antenna that is parallel to the surface of the earth, such as a dipole, produces horizontally polarized waves. One that is perpendicular to the earth's surface, such as a quarter-wave vertical, produces vertically polarized waves. An antenna that has both horizontal and vertical polarization is said to be circularly polarized.

Portable device
A radio transmitting device designed to have a transmitting antenna that is generally within 20 centimeters of a human body.

Potentiometer
Another name for a variable resistor. The value of a potentiometer can be changed over a range of values without removing it from a circuit.

Power
The rate of energy consumption. We calculate power in an electrical circuit by multiplying the voltage applied to the circuit times the current through the circuit (P = IE).

Power supply
A circuit that provides a direct-current output at some desired voltage from an ac input voltage.

Priority traffic
Emergency-related messages, but not as important as Emergency traffic.

Procedural signal (prosign)
One or two letters sent as a single character. Amateurs use prosigns in CW contacts as a short way to indicate the operator's intention. Some examples are K for "Go Ahead," or AR for "End of Message." (The bar over the letters indicates that we send the prosign as one character.)

Product detector
A device that allows a receiver to process CW and SSB signals. Propagation -- The study of how radio waves travel.