Ten-Tec SSB-CW-AM, Инструкция по эксплуатации

Страница: 120 / 135

PRESCALE, Prescaler
Ź
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. This function is built into U3.
REFERENCE FREQUENCY
Ź
a precise, known frequency, usually crystal controlled,
compared with another frequency, as is done in a PLL circuit. See PHASE
DETECTOR, PLL.
RX Ź Abbreviation for receive, receiver, receiving.
SELECTIVITY Ź The filtering capability of a receiver's IF or audio stages, or external
devices, to control, or help you manage, how many signal pitches you hear at the
same time. The selectivity of a receiver may be fixed ("pre-set") or adjustable. A
fixed filter might optimize all 500 Hz audio signals while rejecting all other signals
above or below 500 Hz. A variable filter lets you select a particular "frequency
response" for your receiver such as 500, 600 or 800 Hz, and so forth. Your Model
1254 receiver is specified at "4 kHz @-6d8," which means
SHIEID
Ź
The outer braid of audio or RF coaxial cable, or the aluminum case
enclosing a coil 0r transformer. The metal case of a receiver 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.
SIDEBAND Ź See SSB.
SIP Ź "Single In-Line Pin": Example: U6. [See: DIP].
SSB ("Single Sideband")
Ź
A transmitted signal, usually v0ice, in which both the
carrier and one of the two sidebands are suppressed or greatly reduced. Such
signals require less bandwidth for efficient communication but are not suitable for
broadcast quality needs such as music. The transmitted signal may be either lower
sideband (LSB) or upper sideband (USB). See also AM.
SUPERHET
Ź
a receiver circuit with one or more oscillator-mixer sections which
converts the RF energy from the antenna to a different RF frequency before
demodulation. This is called an "intermediate frequency" (IF). Your receiver is a dual-
conversion superhet. The first IF is 45MHz, and the second IF is 455 kHz.
SWL (Shortwave listening) Ź The popular hobby of just LISTENING to shortwave
communications or broadcasts. If you hear an especially interesting transmission, you
can pursue a "QSL card" confirmation from the transmitting station that what you
heard is confirmed by their own records, or you can just note what you heard in your
own logbook, OR you can discuss what you heard with other SWL enthusiasts via
SWL periodicals, BBS, email or other internet connections.
TIN
Ź
In soldering, to "tin" a wire or copper surface is to heat the wire or surface
with the soldering iron so they become coated with a thin layer of solder.
1254
±
Reference - 27