Ramsey Electronics FX Series Manual page 44

QUADRATURE = Refers to the Phase Angle (90 degrees) considered by the
FM discriminator or detector.
REFERENCE FREQUENCY = a precise, known frequency, usually crystal-
controlled, compared with another frequency, as is done in a PLL circuit. See
PHASE DETECTOR, PLL.
RSSI = "Received Signal Strength Indicator," a function of the MC13135 IC
and comparable circuits which permits MEASURING of the relative strength of
a received signal. A few microamps of variation can be interpreted as DB
(decibels) of signal strength.
RX = Abbreviation for receive, receiver, receiving. [See: TX]
SPEAKER-MIKE = speaker and microphone functions contained in the same
physical housing, as in the design of simple home intercoms. For ham
operators, this means that both speaker and microphone are in a microphone
casing with separate plugs from a common cord. Since such accessories can
use ANY style of plug for either mic or speaker function, Ramsey Electronics
has adopted the popular ICOM-compatible standard for the FX transceivers.
SHIELD = The outer braid of audio or RF coaxial cable, or the aluminum case
enclosing a coil or transformer.The metal case of a transceiver also performs
an important RF shielding function.The shield blocks or protects a coil from the
effect of nearby objects that would change its inductance. The shielding on
cable prevents the inner wire from radiating (RF) or from picking up stray
radiation such as AC hum.
SQUELCH = means literally, to subdue utterly or crushingly! In radio
communication, usually VHF and UHF, squelch is the circuitry needed to
subdue (mute) the background noise until a detected signal "breaks" the
squelch.
SUPERHET = A receiver design that converts the incoming desired frequency
to a lower Intermediate Frequency (IF) where most of the gain and bandpass
characteristics reside.
TOROID = A style of making coils or inductors where the insulated wire is
threaded ("wound") around a metallic form shaped like a doughnut. This style
of coil making generally eliminates any need for additional shielding which
may be needed to make the coil's inductance immune to the presence of other
nearby components or objects with metallic content.
TRIMMER = either a capacitor or resistor, miniature and variable, intended to
permit exact, final adjustment of circuit values.
TX = Abbreviation for transmit, transmitter, transmitting.
T-R = Abbreviation for "Transmit-Receive Switching", which can be
accomplished by manual switches, relays or solid-state devices such as the
PIN diodes used in the FX transceivers.