Operation Manual

Page 55FT-991 OperaTing Manual
tools for coMfortable anD effective reception
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nd 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
rst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
preamplier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