Radio Shack 20-164 User Manual page 12

If.you.set.the.squelch.precisely.at.the.threshold.
where.the.hissing.sound.stops,.the.scanner.
may.pick.up.unwanted,.partial,.or.very.weak.
transmissions..To.prevent.this,.most.users.
prefer.a.position.a.bit.past.the.threshold.
With.the.attenuator.on,.the.scanner.might.
not.receive.weak.signals..You.can.reduce.
interference.using.two.attenuator.modes:.
•. Global.–.(Default).The.attenuator.setting.is.
applied.to.all.channels,.bands,.or.groups..
•. Normal.–.Lets.you.set.the.attenuator.in.
each.channel,.band,.or.group..
To set squelch:
1.. Turn.off.the.scanner.and.turn.SQUELCH.
fully.counterclockwise.
2.. Turn.on.the.scanner..You.should.hear.a.
hissing.sound.
3.. Turn.the.SQUELCH.clockwise.to.
decrease.the.scanner's.sensitivity,.turn.
counterclockwise.to.increase.its.sensitivity.
To set the attenuator mode:
1.. To.set.Global.mode,.press.FUNC.and.then.
ATT..On.the.display."G".appears.".
2.. To.set.the.attenuator.for.each.channel,.press.
FUNC.and.then.ATT..On.the.display."G".
disappears..To.turn.the.attenuator.on.or.off.
for.each.channel:
•. On.–.Press.ATT.."A".appears..
•. Off.–.Press.ATT.again.."A".disappears."
You cannot set the attenuator while
scanning.
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