Ramsey Electronics FZ-146 Specifications download pdf (Page 42)

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elements connected to RF ground, the horizontal elements are called a

"groundplane."

HIGH = In solid-state circuitry, to say a given device pin or circuit point is at a

"logic high" is to say that it shows a + DC supply voltage at that point.

Switching to the opposite state (LOW) or back again for some specific

purpose is a fundamental capability of the circuit.

HOUSE-NUMBER = A manufacturer's part number different from the

industry-standard description of a part. Example: LB3303HK (L1)

HYSTERESIS = the ability of an FM squelch circuit to remain open after

being broken by a weak signal which fluctuates further.

INPUT, INVERTING = see "Op Amp"

INPUT, NON-INVERTING = see "Op Amp"

I/O = acronym meaning "Input and Output" port or connection.

JUMPER = Short, plain wire, soldered to interconnect points in a circuit not

otherwise connected by board traces or other wiring.

KEY, "to key" = to turn on a transmitter's carrier signal momentarily, whether

by a telegraphy code key (the root of this very common radio jargon) or by a

push-to-talk switch.

L-C = A tuned circuit made of inductor (L) and capacitor (C).

LIMITER = The portion of an FM receiver circuit which chops off noise and

AM (amplitude modulation). It processes the IF signal so that only FM will be

detected.

LOCAL OSCILLATOR (LO) = An oscillator in a superhet receiver whose

output is mixed with another signal such as antenna input. See SUPERHET.

LOCK = The condition in a phased-locked-loop (PLL) in which all sections

are working together as intended and designed.

LOOP-FILTER = (See PLL). The output of a PLL phase detector is in the

form of pulses. The frequency of those pulses depends on the reference

frequency. The loop filter smooths out these pulses into a clean DC control

voltage for the VCO. (See: VCO)

LOW = A logic level at or near zero volts. (See HIGH).

MATRIX = A methodical criss-crossing of many connections.

MC- = Prefix for parts made by Motorola, Inc.

MIXER = A circuit section which gets two or more inputs and delivers a

single output. The output is equal to the sum of the input frequencies and

also to the difference between them.

MODULATION = See also: CW, FM. "Modulation" is simply the process of

imposing variations on a steady RF signal from an audio source such as

voice, music or data (see: AFSK).

MUTE = to turn off, to render silent. (See also SQUELCH)

N = can be any number to solve in a classroom problem, but "N" is THE

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Ramsey Electronics FZ-146 Specifications Page 42