DRAKE R8A - Getting Started contd.; Gain and AGC OPERATION; HOW AGC, RF GAIN AND THE SIGNAL METER WORK TOGETHER

19 Getting Started cont'd.
DRAKE F&A Communications Receiver
Aaa Se ae
(SCAN)
MEM SEEK
UsT TIME rate
TUNE
A-B CARR
VFO (A) =(B) , (PRE) AGC (B) (F)
AaB | anno THE |
SIGNAL METER
i ‘NOTCH \
888
AGC function button and disloay
(FAST, SLOW and OFF)
NB (NW)
| quame) |
MHz ®W) (MoE)
AUTO Rin SYNC
kHz so ao — usB
CW FM
“aa RITY
12 ON OFF
TIMER CLK/FREQ
step |
(LOCK)
RF control knob (gain)
(CLOCKWISE and COUNTERCLOCKWISE)
FIGURE 11
Gain and AGC OPERATION
In a basic sense, gain means amplification. AGC is an
abbreviation for Automatic Gain Control. Thus, AGC
helps tune in weak signals by conveniently amplifying
them automatically. When a strong signal is tuned in, the
AGC automatically reduces the amplification since it is
not needed, This also prevents overloading the receiver
and minimizes distortion. When factory supplied, AGC
can be selected to operate S(LOW) or F(AST). The SLOW
AGCsetting is used forreception of slowly changing signal
levels such as SSB signals. The FAST AGC setting allows
more rapid automatic receiver gain adjustment to fast
changing signal levels such as AM signals. The user can
select an off position, if desired. To select this feature,
press and hold the AGC function button until a memory
confirmation beep is heard. The AGC button will now
permit SLOW, FAST or OFF settings. The OFF condition is
indicated by the display not showing a ___|around Sor
F. Toremove the OFF selection option, repeat the press-
and-hold sequence. If the AGC is tuned off, the receiver
gain must be manually set by using the RF (gain) control
knob to produce distortion free reception.
HOW AGC, RF GAIN AND THE SIGNAL METER WORK TO-
GETHER
The AGC function button, RF Gain control knob and the
SIGNAL METER work together in the same circuit in three
basic ways.
1) Fully Automatic Gain Control -
Selecting either the S(LOW) or F(AST) AGC setting and full
clockwise RF Gain setting makes the gain (amplification)
control fully automatic. No other gain adjustments are
required. Using the AGC is the most convenient way to
operate the receiver and is recommended for almost all
receiving conditions.
The Signal Meterneedle automatically fluctuates with the
strength of the signal received. A weak signal is indicated
by thesignal meterneedle moving to the left (for example
- 3). Astrongsignalisindicated by the signal meter needle
moving to the right (for example - 40).
2) Manual Gain Control With AGC On (Slow or Fast) -
The maximum gain level can be reduced manually, as
desired, by using the RF control knob. Turning the RF
control knob counterclockwise will reduce the gain, caus-
ing the signal meter needle to move upscale. With the
gain reduced manually, there will be less background
noise when no signal is present, but signals stronger than
the S-meter setting will be received normally.
3) Manual Gain Control With AGC Off -
With the AGC off, the RF Gain control must be rotated
counterclockwise until the gain is reduced to the point
where no signal distortion occurs. This mode of operation
is seldom used.