DRAKE R8A - Page 36

1) AC Input- Alternating Current power source available
at wall outlet sockets.
2) AM - Amplitude Modulated signals in which the infor-
mation or intelligence being transmitted changes the
instantaneous amplitude of the transmitted carrier.
Not to be confused with the AM Broadcast Band (fre-
quencies of 540 to 1610 kHz).
3) AGC - Automatic Gain Control which is employed in
receivers to adjust the amount of gain in the receiver's
circuitry to prevent distortion and maintain a nearly con-
stant audio volume level over wide variations in received
signal strength.
4) Attenuation - Loss, as applied in the text of this manual,
added prior to the input stages of the receiver to reduce
the level of very strong signals that may occur on certain
bands, in certainlocations, at certain times or a combina-
tionof all three factors. Each 10dB (decibel) step reduces
the power of the received signal by a factor of ten.
5) CW- Continuous Wave transmission signals. Actually,
the signal is keyed on and off at precise intervals to
convey information. Morse code isthe most common CW
signal.
6) DC Input - Direct Current power source such as is
available from batteries or regulated power supplies.
Lead acid storage batteries, such as employed in cars
and boats, have a 12-14 volt DC output which is the
proper operating voltage for the receiver's DC input.
Another requirement ofthe battery isits AMP-HR rating. To
determine the number of hours of operation before bat-
tery recharging is required, divide the AMP-HR rating of
the battery by (2 AMPS) the current requirement of the
receiver.
7) Dynamie Range - Ability of the receiver to faithfully
reproduce high quality audio over a wide range of signal
strength conditions - from very weak signals to very strong
signals.
8) Frequency - Rate of reoccurrence in heriz or cycles/
second of electromagnetic wave or carrier.
9) FM - Frequency Modulated signals in which the infor-
mation or intelligence being transmitted changes the
instantaneous frequency of the transmitter carrier.
Notto be confused with the FM Broadcast Band (frequen-
cies of 88 to 108 MHz).
10) High Q, Electronically Switched Filter - A multi band-
width filter with high adjacent channel attenuation
switched electronically.
11) GMT- Greenwich Mean Time.
12) LCD - Liquid-crystal display - composed of two
Glossary of Terms 34
parallel glass plates with conductive coatings sandwich-
ing a liquid-crystal compound between them, The com-
pound becomes opaque and reflective when subjected
to an electric field, LCD displays are used as information
displays on many types of electronic equipment.
13) LSB - Lower Side Band, the mirror image of the USB
containing all of the modulation information of amplitude
modulation in one half the bandwidth. The lower half,
excluding the carrier, of an AM signal.
14) Notch - Aresponse producing attenuation of signals
over a narrow range of frequencies.
15) Passband Offset - A frequency conversion technique
which skews the desired channel off center of the detec-
tion filters allowing low or high frequency components to
be selectively attenuated.
16) Passive Double Balanced Mixer- A frequency conver-
sion device requiring alocally generated oscillator (LO) to
operate. Anincoming RF signal is shifted relative to the LO
producing an intermediate or IF frequency.
17) RF- Radio frequency
18) RS232 - Electronics Industries Association standard
physical-level interface between DIE (terminal) and DCE
(modem).
19) RITY - Radio Teletype communications.
20) Squelch - A user controlled adjustment which mutes
the audio output below a certain signal strength.
21) Synchronous Detector - An amplitude modulation
detector which utilizes a replica of the original transmitted
carrier signal to improve the reception of weak signals.
22) Synthesized - Capable of generating a large number
of different output frequencies, all related to a single,
highly stable reference source.
23) Up Conversion - A frequency conversion technique
that translates an incoming RF signal to a higher fre-
quency.
24) USB - Upper side band, the mirror image of the LSB
containing all of the modulation information of amplitude
modulation in one half the band width. The upper half,
excluding the carrier, of an AM signal.
25) UTC - Universal Time Coordinated.
26) VFO - Variable frequency oscillator
27) VHF - Very High Frequency band extends from ap-
proximately 30MHz to 300 MHz.