From QRZ.Com, the Icom handout, and Part 97 Of The FCC Rules -
Ham Radio Glossary - An overview of amateur radio terms.

S/N
Signal To Noise Ratio

SAR
Search And Rescue

SASE
"Self Addressed, Stamped Envelope"; for more information, please see
QRZ's "QSL Corner" at http://www.qrz.com/qsl.html.

Scan
Continually sweeping frequencies looking for signals.

Scan Edge.
End and start frequencies for a scanning range.

Semi Duplex
An operation mode in which transmits and receives are
accomplished on different frequencies alternatively.

Sensitivity
Indicates how weak a signal the reciver will pick up.

Set mode.
An peration mode used for radio to set less frequently used control
features.

SFI
See "Solar Flux Index"

SHF
(super-high frequency). The frequency range 3-30 GHz.

Simplex
Communicating directly from radio to radio (without the use of an
intermediary repeater). This term is normally used in the context of environments that frequently use repeaters. With simplex, the frequency
is identical to all stations on that frequency.

Simplex Repeater
A radio that has a digital audio store-and-forward relay system. Produces results similar to that of a conventional repeater.

Slug
A short, cylindrical unit that is inserted into a Bird® Wattmeter (or
similar) that allows the unit to read power (watts) for a particular
frequency range. A slug always has a finite frequency range and a maximum
power rating. By swapping out different slugs, the wattmeter can be used
for many different frequencies and power ranges.

Skywarn
Trained volunteer severe storm spotters for the National Weather Service.

SMA
Sub-Minature a connector)
A type of antenna connector used on VHF/UHF portable rigs, such HT's.

Solar Flux Index
A measurement of radio emission from the sun. HF propagation conditions
are considered good when this number is high and the A- and K-index numbers
are low.

SP
Speaker

Space station
An amateur station located more than 50 km above the Earth's surface.

Space telemetry
A one-way transmission from a space station of measurements made from the measuring instruments in a spacecraft, including those relating to the functioning of the spacecraft.

Special Event
A radio operating event, usually on HF, in which a group or organization celebrates an event or holiday by making contacts and offering special QSL cards or certificates to confirm the contact. Ham Radio magazines, such as
QST, usually publish a monthly list of Special Events.

Split
A mode in which the transmit and receive frequency is different.

Spurious emission
An emission, on frequencies outside the necessary bandwidth of a
transmission, the level of which may be reduced without affecting the information being transmitted.

SQL
Squelch. A function muting audio output for set conditions.

SSB
Single Sideband

SSTV
Slow Scan Television. Graphics Communication using narrow bandwidth.

Straight Key
A device for sending Morse Code, consisting of a single arm making contact
with another point to complete a circuit and key a transmitter (thanks to WD5CTQ).

Switching Power Supply
A power supply that uses switching transistors (on-off) to increase the efficiency of the power conversion, rather than the simple transformer/rectifier design of traditional power supplies.

SWL
"Shortwave Listener"; one who enjoys listening to shortwave transmissions, without intention of transmitting.

SWR
"Standing Wave Ratio"; an indication of how well matched an antenna is to
its transmitter. A "one to one" (1:1) SWR indicates a perfect match.
Anything less than 1:1 (i.e., 2:1) indicates that the antenna is not
perfectly resonant for the transmit frequency, and that some RF power is
being reflected back down the transmission line into the transmitter. In general, any SWR which is 3:1 or better is acceptable.
--- SBBSecho 3.20-Win32
* Origin: The Thunderbolt BBS - Little Rock, Arkansas (1:2320/33)