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.

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

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

Set 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

14

Page 17
Image 17
Icom IC-R8500 instruction manual Squelch function, Functions for FM, Functions for SSB/CW, Center indicator, If shift

IC-R8500 specifications

The Icom IC-R8500 is a highly regarded general-purpose receiver that has made its mark among amateur radio enthusiasts and professionals alike. This versatile communication receiver is known for its wide frequency coverage, advanced features, and robust design, making it a valuable tool for various applications, including shortwave listening, public safety communication, and aircraft monitoring.

One of the standout features of the IC-R8500 is its extensive frequency coverage. It spans a range from 0.1 MHz to 3 GHz, allowing users to access a wide spectrum of signals. The receiver includes coverage of HF, VHF, UHF, and even microwave bands, making it suitable for listening to everything from amateur radio transmissions to satellite communications.

The receiver employs a high-performance double-conversion superheterodyne architecture, which contributes to its excellent sensitivity and selectivity. The advanced RF circuitry minimizes interference and enhances the clarity of received signals. Users can expect outstanding audio quality and a wide dynamic range, even in challenging reception conditions.

Digital Signal Processing (DSP) is another key technology incorporated into the IC-R8500. The DSP capabilities allow users to apply noise reduction and filtering techniques to improve the quality of the received audio. Features such as automatic notch filtering and IF filtering help eliminate unwanted noise, enhancing the listening experience.

The IC-R8500 is equipped with a large, easy-to-read LCD display that provides information on frequency, mode, signal strength, and other essential parameters. The user-friendly interface simplifies operation, allowing quick access to various settings and functions. Additionally, the receiver supports various modulation modes, including AM, FM, SSB, and CW, catering to different listening preferences.

For those seeking enhanced connectivity, the IC-R8500 offers multiple options, including an audio output jack, and external speaker connections. It also has a built-in memory function, allowing users to store and recall favorite frequencies easily. The receiver can be controlled via a computer interface, offering versatility for advanced users and programmers.

In summary, the Icom IC-R8500 stands out for its wide frequency range, superior sensitivity, and advanced features powered by DSP technology. Its robust construction and user-friendly design make it a favorite among communications enthusiasts seeking a reliable and versatile receiver for various applications. Whether for hobbyist listening or professional use, the IC-R8500 remains a top choice in the world of radio receivers.