Agc (Automatic Gain Control) Selection; Noise Blanker Selection And Setting - Yaesu FT-1000MP Operating Manual

Operation
When looking for weak signals on a quiet band
you will want maximum sensitivity, so the IPO
should be disabled and ATT selector set to 0.This
situation is typical during quiet times on frequen-
cies above 20 MHz, and when using a small
antenna on other bands.
AGC (Automatic Gain Control)
Selection
When tuning around the band AGC
looking for signals, the AGC se- orr FAST stow
lector is usually best kept in the _ AUTO
AUTO position, where AGC de-
cay is automatically selected ac-
cording to the operating mode.
You can manually select receiver AGC; however,
a few points about AGC and receiver recovery
time need to be pointed out.
For SSB reception, the FAST position allows
the receiver gain to recover quickly after tuning
past strong signals or when fast fading occurs.
However, once you have a station tuned in, recep-
tion will usually be more comfortable if you switch
to the SLOW position (keeping the receiver from
picking up low-level noise during pauses in
speech).
For CW reception, when several signals are
present in the passband, the FAST position can
avoid AGC "pumping" (gain fluctuations) caused
by strong undesired signals. For AM reception,
the SLOW position is usually better, and for 300-
baud packet and RTTY/AMTOR, the FAST or OFF
positions will usually give the fewest errors/re-
tries.
RF Gain Setting
When tuned to a moderate RF GAIN
strength signal, if low level back- =
ground noise is still present after rx
setting the ATT selector, try reduc- i! :
ing the RF GAIN control from the ° i
fully clockwise position. This reduces the signal
input to the first mixer via a PIN diode attenuator
and causes the minimum S-meter reading to
move up the scale, often clearing up the back-
ground noise and putting the desired signal more
"in the clear." Remember, however, to return this
control fully clockwise when you want to receive
weak signals, or read low levels on the S-meter.
Also read the box on this page.
Note on AGC
The AGCOFF position disables the
overload-protection normally provided by the
AGC circuitry. If the RF gain control is left fully
clockwise in this condition, the RF and IF
amplifiers can be easily overloaded (causing
distortion) when a strong signal is received.
Correct the overload either by setting the AGC
selector to another position, or by turning the
RF control counterclockwise to set receiver
gain to a comfortable level.
Noise Blanker Selection and Setting
The two noise blanker cir- key, chee
cuits in the FT-1000MP are
provided for two different
NOTCH—2— NB
1 button activates the narrow
pulse blanker, for short pulse
noise such as from switching
tions and power lines. This blanker can some-
times also reduce the level of static crashes from
electrical storms. The NB-2 button activates the
pulse noise. If you hear any of these types of
noise, just press either the NB-1 or NB-2 button so
that the green LED above it lights, and turn the
types of pulse noise. The NB-
@
transients, automobile igni- ©
wide pulse blanker, for longer duration man-made
outer NB control clockwise.
If the blanker seems to distort a signal you're
listening to, reduce the setting for optimum read-
ability, or turn it off.
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