The IC-R8500 has 2 types of squelch, noise squelch
and S-meter squelch.
Noise squelch:
Only acts on noise; has good sen-
sitivity. It can be adjusted for reception of weak sig-
nals. Strong signals exceeding a certain level will
always cause the squelch to open.
S-meter squelch:
S-meter squelch does not open
for weak signals but can be adjusted to open for sig-
nals over a wide range of strengths. Once you have
selected a threshold point in a range, the IC-R8500
will open for all signals above this point.
To adjust the squelch, rotate [SQUELCH].
• Clockwise rotation closes the squelch (sets the thresh-
old point higher); counterclockwise rotation opens the
squelch (for reception of weak signals).
FM signals have a wide bandwidth which makes
them easy to receive. However, you may be tuned
off-center resulting in audio distortion. The IC-R8500’
s off-center indicators appear in such cases, making
it easy to fine tune to the center of the frequency.
AFC stands for automatic frequency control. The AFC
circuit automatically compensates the tuning when a
receive frequency drifts or goes off frequency.
When one of the off-center indicators appears, the
IC-R8500 can adjust the receive frequency auto-
matically—when the AFC function is turned ON and
an off-center frequency is received, the frequency
in the display automatically changes to reflect the
center of the signal.
14
4
RECEIVE FUNCTIONS
■
Squelch function
■
Functions for FM
D
Center indicator
S-meter squelch
threshold
Noise squelch
threshold (not
available in SSB,
CW, WFM and
AM narrow modes)
• Signals below the
S-meter level
are muted.
When [SQUELCH] is
rotated past center,
the S-meter shows
the signal strength
needed to open the
squelch.
SIGNAL
S
1 3 5 7 9 +20dB +60dB
RECV
One of these indicators appears when the received
signal is off-center.
RECV
When one of these indicators appears, the
displayed frequency is automatically moved to the
center frequency.
AFC
D
AFC
The
IF shift
function electronically changes the
center of the IF (intermediate frequency) passband
frequency to reject interference. The IF shift is not
available in FM and AM modes.
q
Adjust the [SHIFT] control for a minimum interfer-
ence signal level.
• The audio tone may be changed while the IF shift is in
use.
w
Set the shift control to its center position when
there is no interference.
■
Functions for SSB/CW
D
IF shift
Shifts low
Center
Shifts high
IF SHIFT
APF
IF SHIFT
APF
IF SHIFT
APF
