3
BASIC OPERATION
24
2001 NEW
Adjusts the RF gain and squelch threshold level. The
squelch removes noise output from the speaker
(closed position) when no signal is received.
•The squelch is particularly effective for FM. It is also avail-
able for other modes.
•The control can be set as the RF gain control only (squelch
is fixed open) or squelch control (RF gain is fixed at maxi-
mum) in set mode (p. 81). See below right.
•The 11 to 12 o’clock position is recommended for any set-
ting of the [RF/SQL] control.
Adjusting RF gain (Receive sensitivity)
Normally, [RF/SQL] is set to the 11 o’clock position.
Rotate [RF/SQL] to the 11 o’clock position for maxi-
mum sensitivity.
•Rotating counterclockwise from the maximum position re-
duces sensitivity.
• The S-meter indicates receive sensitivity.
Adjusting squelch (Removing non-signal noise)
Rotate [RF/SQL] clockwise when receiving no signal,
until the noise just disappears.
• [RX] indicator light goes out.
•Rotating [RF/SQL] past the threshold point invokes the S-
meter squelch— this allows you to set a minimum signal
level needed to open the squelch.
• When setting as RF gain/squelch control
• When functioning as RF gain control (Squelch is
fixed open; SSB, CW, RTTY only)
•When functioning as squelch control (RF gain is
fixed at maximum)
Squelch is
open.
S-meter
squelch
S-meter squelch
threshold
Noise squelch
threshold
(FM mode)
Shallow Deep
Noise squelch (FM mode)
Minimum RF gain
Adjustable
range
Maximum
RF gain
Recommended level
RF gain
adjustable
range
Maximum
RF gain
S-meter
squelch
Noise squelch (FM mode)
Squelch is
open.
■ Squelch and receive (RF) sensitivity
SET MODE OPERATION
RF+SQL
Can be used in all modes.
(default)
Functions as noise squelch or S-meter
squelch in AM and FM; S-meter
squelch only in other modes.
SQL
➥ Operates as a squelch control.
• RF gain is fixed at max. sensitivity.
➥ Operates as an RF gain control in
SSB, CW and RTTY.
AUTO •Squelch is fixed open.
➥ Operates as a squelch control in AM
and FM.
• RF gain is fixed at max. sensitivity.
IC-7400.qxd 02.4.2 11:35 Page 24
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