5-2 PLL ADJUSTMENTS

 

 

 

 

MEASUREMENT

 

 

ADJUSTMENT

ADJUSTMENT

ADJUSTMENT CONDITION

 

VALUE

POINT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

UNIT

LOCATION

 

UNIT

ADJUST

 

 

 

 

 

 

 

 

30.2 MHz

1

• Display frequency: Any

PLL

Connect an RF volt-

–10 dBm (or more than

PLL

R570

LEVEL

 

• Receiving

 

 

meter or

spectram

–11.5 dBm, when R570

 

 

 

 

 

 

 

analyzer

to

check

is in maximum posi-

 

 

 

 

 

 

 

point J541.

 

tion.)

 

 

 

 

 

 

 

 

 

 

REFERENCE

1

• Display frequency: Any

PLL

Connect an RF volt-

Maximum level

PLL

Adjust in

FREQUENCY

 

• Receiving

 

 

meter or

spectram

(–13 dBm to –7dBm)

 

sequence

 

 

 

 

 

analyzer

to

check

 

 

L551, L552

 

 

 

 

 

point P551.

 

 

 

s e v e r a l

 

 

 

 

 

 

 

 

 

 

times.

 

 

 

 

 

 

 

 

 

2

This adjustment must be performed

 

Connect a frequency

60.400000 MHz

 

The trimmer

 

 

at 5 minutes later after power ON.

 

counter

to

check

 

 

capacitor of

 

 

 

 

 

point P551.

 

 

 

X512.

 

 

 

 

 

 

 

 

 

 

144M LOCK

1

• Display frequency: 173.9800 MHz

PLL

Connect

a

digital

2.7 V

PLL

L193

VOLTAGE

 

• Mode

: USB

 

multimeter or oscillo-

 

 

 

 

 

• Receiving

 

 

scope to check point

 

 

 

 

 

 

 

 

CP100.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

• Display frequency: 136.0200 MHz

 

 

 

 

0.6 V to 1.6 V

 

Verify

 

 

• Receiving

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3

• Display frequency: 155.0000 MHz

 

Connect an RF volt-

–10 dBm to –4 dBm

 

Verify

 

 

• Receiving

 

 

meter to check point

 

 

 

 

 

 

 

 

P251.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

440M LOCK

1

• Display frequency: 479.9800 MHz

PLL

Connect

a

digital

3.4 V

PLL

C402

VOLTAGE

 

• Mode

: USB

 

multimeter or oscillo-

 

 

 

 

 

• Receiving

 

 

scope to check point

 

 

 

 

 

 

 

 

CP300.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

• Display frequency: 420.0200 MHz

 

 

 

 

0.5 V to 1.5 V

 

Verify

 

 

• Receiving

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3

• Display frequency: 450.0000 MHz

 

Connect an RF volt-

–16 dBm to –10 dBm

 

Verify

 

 

• Receiving

 

 

meter to check point

 

 

 

 

 

 

 

 

P421.

 

 

 

 

 

 

 

 

 

 

 

 

 

MAIN BFO

1

• Display frequency: Any

PLL

Connect an RF volt-

–11 dBm to –5 dBm

PLL

Verify

LEVEL

 

• Mode

:USB

 

meter to check point

 

 

 

 

 

• Receiving

 

 

P601.

 

 

 

 

 

 

 

 

 

 

 

 

 

SUB BFO

2

• Sub display freq. : Any

PLL

Connect an RF volt-

–11 dBm to –5 dBm

PLL

Verify

LEVEL

 

• Mode

:USB

 

meter to check point

 

 

 

 

 

• Receiving

 

 

P701.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5-3 FREQUENCY ADJUSTMENT

 

 

 

 

MEASUREMENT

 

ADJUSTMENT

ADJUSTMENT

ADJUSTMENT CONDITION

VALUE

POINT

 

 

 

 

 

 

 

 

 

 

UNIT

LOCATION

 

UNIT

ADJUST

 

 

 

 

 

 

 

 

FM TX-LO

1

• Display frequency: Any

MAIN

Connect a frequency

10.85000 MHz

MAIN

L255

FREQUENCY

 

• Mode

: FM

 

counter to check

 

 

 

 

 

• Disconnect P501, P502 (PA unit)

 

point CP51.

 

 

 

 

 

from J51 and J52 on the MAIN unit.

 

 

 

 

 

 

 

• Apply no audio signals to [MIC]

 

 

 

 

 

 

 

connector.

 

 

 

 

 

 

 

 

• Transmitting

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

After adjustment, connect P501, P502 (PA unit) to J51, J52 on the MAIN.

5 - 2

Page 20
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Icom IC-910H service manual PLL Adjustments, Frequency Adjustment

IC-910H specifications

The Icom IC-910H is a highly regarded and versatile transceiver that is designed for amateur radio operators who are particularly interested in V/UHF and microwave communications. Known for its exceptional performance, the IC-910H encompasses a suite of features that make it a standout choice for both casual and dedicated hams.

One of the main features of the IC-910H is its dual-band capability, allowing for simultaneous operation on both 144 MHz (2 meters) and 430 MHz (70 centimeters) bands. This dual operation enables users to engage in various communication modes, including SSB, CW, FM, and digital. Its high frequency stability ensures that users can rely on the transceiver for accurate and consistent transmissions.

The IC-910H is equipped with a high-performance 10 MHz IF filter that improves selectivity and reduces adjacent channel interference. The optional 1.2 GHz module enhances the transceiver’s capabilities, allowing operators to venture into microwave frequencies. This expandability is a significant advantage for users who wish to progress in their amateur radio pursuits.

Another notable aspect of the IC-910H is its large, easy-to-read LCD display, which features various color options for enhanced visibility. The front panel layout is user-friendly, providing quick access to important controls and functions. The built-in DSP (Digital Signal Processing) technology offers noise reduction and filtering capabilities, significantly improving overall audio quality and making weak signals more intelligible.

The transceiver also includes extensive memory functions, with up to 1,000 memory channels available for storing frequencies, modes, and operational settings. Additionally, it supports CTCSS and DCS tones, which facilitate the use of repeater systems and private group communications.

In terms of build quality, the IC-910H features a robust construction designed for durability and long-term use. Its efficient power supply management ensures excellent performance while minimizing heat generation, making it suitable for extended operating sessions.

Overall, the Icom IC-910H is a powerful and feature-rich transceiver that is favored by many amateur radio enthusiasts. With its versatile operating modes, advanced filtering capabilities, and clear display, it stands out as a reliable tool for both casual operators and serious DXers. Its well-thought-out design and comprehensive features make it a valuable addition to any ham's station collection.