Icom IC-R8500 Squelch function, Functions for FM, Functions for SSB/CW, D Center indicator, D Afc

RECEIVE FUNCTIONS 4

■Squelch function

The IC-R8500 has 2 types of squelch, noise squelch and S-meter squelch.

Noise squelch: Only acts on noise; has good sensi- tivity. It can be adjusted for reception of weak signals. 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 signals over a wide range of strengths. Once you have selected a threshold point in a range, the IC-R8500

Noise squelch threshold (not available in SSB, CW, WFM and

AM narrow modes)

S-meter squelch threshold

• Signals below the S-meter level are muted.

will open for all signals above this point.

To adjust the squelch, rotate [SQUELCH].

•Clockwise rotation closes the squelch (sets the threshold point higher); counterclockwise rotation opens the squelch (for reception of weak signals).

When [SQUELCH] is	S 1 3 5 7 9 +20dB +60dB
rotated past center,
the S-meter shows
the signal strength	SIGNAL
needed to open the
squelch.

■Functions for FM

DCenter indicator

FM signals have a wide bandwidth which makes them
easy to receive. However, you may be tuned off-cen-	RECV
ter 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.	One of these indicators appears when the received
	signal is off-center.

DAFC

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 automat- ically—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.

AFC

RECV

When one of these indicators appears, the displayed frequency is automatically moved to the center frequency.

■Functions for SSB/CW

DIF shift

The IF shift function electronically changes the cen- ter of the IF (intermediate frequency) passband fre- quency to reject interference. The IF shift is not avail- able in FM and AM modes.

➀Adjust the [SHIFT] control for a minimum interfer- ence signal level.

•The audio tone may be changed while the IF shift is in use.

➁Set the shift control to its center position when there is no interference.

APF IF SHIFT APF IF SHIFT APF IF SHIFT

Shifts low Center Shifts high

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