Ramsey Electronics FX-440 Manual page 46

PLL = "Phase-Locked-Loop,• a frequency gererator circuit in which a free running voltage
controlled oscillator output is stabilized by frequency dividers and a phase detector which
controls and corrects the voltage supplied to varactor diode(s) which determine oscillator
frequency.
"POT"
=
jargon for "potentiometer•, a variable resistor, either a panel control or a "mini"
device on a PC board.
PRESCALE, Prescaler
=
a circuit or device which divides an incoming frequency down to a
lower frequency so that it can be handled more easily by later digital counting circuitry or
devices.
PTI = "push to talk", referring to all switches and circuitry involved in turning a transmitter
of and off from a switch usually built into a microphone. This switch may also be a relay or
transistor in a packet TNC, etc.
"PUFF" = No, not the magic dragon. It's an easier way to say "picofarads" in the Ramsey
warehouse and other hi-tech temples.
QUADRATURE = Refers to the Phase Angle (90 degrees) considered by the FM
discriminator or detector.
REFERENCE FREQUENCY = a precise, known frequency, crystak:ontrolled, compared
with another frequency, as is done in a PLL circuit. See PHASE DETECTOR, PLL.
RSSI = "Received Signal Strength Indicator,• a function .of the MC3335 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 (decibles) 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 metal 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 sh10lding 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
=
Receiver design technique where the desired incoming signal is converted
to an Intermediate Frequency (IF) for the bulk of the receiver's gain and bandpass
characteristics.
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 (See: SHIELD) 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. ·
Ref. 44
FX-440