Icom IC-M21 Service Manual - page 15

5 - 3

5-2 PLL AND RX SENSITIVITY ADJUSTMENTS

LOCK 

VOLTAGE

RX

SENSITIVITY

ADJUSTMENT

ADJUSTMENT

ADJUSTMENT CONDITION

MEASUREMENT

VALUE

POINT

UNIT

LOCATION

UNIT

ADJUST

1

2

1

• Operating channel : ch16

• Receiving

• Operating channel : ch16

• Output power

: Low

• Transmitting

• Operating channel : ch16

• Set an SSG as:

Frequency

: 156.8 MHz

(ch. 16)

Level

: 3.2 µV*

(–97 dBm)

Modulation

: 1 kHz

Deviation

: ±3.5 kHz

• Receiving

MAIN

Top

Panel

Connect a digital

multi-meter or oscil-

loscope to the

check point CP1.

Connect an SSG to

the antenna con-

nector and a SINAD

meter with 8 

Ω

load

to the [SP] jack.

1.8 V

1.7 V

0.35 µV (–116 dBm)

[M2A]

0.56 µV (–112 dBm)

[M21]

Verify

Verify

CP1

PLL lock voltage 

check point

*The output level of the standard signal generator (SSG) is indicated as the SSG’s open circuit.