Yaesu FT-991A, Руководство по эксплуатации, Страница: 59 / 158

Page 57 FT- 991 Operating Manual
RF Gain
The RF Gain control provides manual adjustment of the gain levels for the receiver RF and IF stages, to account for
noise and signal strength conditions at the moment.
1. The
RF GAIN knob should, initially, be rotated to
the fully clockwise position. This is the point of
maximum receiver sensitivity.
2. Counter-clockwise rotation of the RF GAIN knob
will gradually reduce the system gain.
Advice:

As the RF GAIN knob is rotated counterclockwise
to reduce the gain, the S-meter reading will rise. This
indicates that the AGC voltage being applied to the
receiver is increasing (this causes a reduction in re-
ceiver gain).

Rotating the RF GAIN knob control to the fully
counter-clockwise position will essentially disable
the receiver, as the gain will be greatly reduced. In
this case, the S-meter will appear to be “pegged”
against the right edge of the analog S-meter scale.
Quick Point:

Reception frequently can be improved by rotating
the RF GAIN knob slightly counter-clockwise to the
point where the “stationary” meter indication is set
just about the same as the incoming noise level. This
will reduce the RF gain to find a level of improved
signal to noise ratio.

The RF Gain control, along with the IPO and the At-
tenuator features, all affect the system receiver gain
in different ways. The IPO generally should be the
first feature engaged when dealing with a high noise
level, or a crowded, high-level signal environment.
Also, the IPO generally should be the first feature
engaged, if the frequency is low enough to allow the
preamplifier to be bypassed. Thereafter, the RF Gain
and Attenuator features may be employed to provide
precise, delicate adjustment of the receiver gain to
fully optimize performance.
RF GAIN Knob
Tools for Comfortable and Effective Reception