Furuno FS-1570 Service Manual

7.4 TX Gain
7-17
7.4 TX Gain
TX gain is adjusted by using the potentiometers tabulated below. Weak audio is often
caused by the transmitter gain being set too low. Excessive pickup of background noise
is often caused by the microphone gain being set too high. See Fig. 7.5.2 for the
location of the adjusters.
Table 7.4.1 TX Gain Adjusters
Item Condition Measurement Adjuster Rating
LINE IN signal
Pins #7 and
#8 of J5 on
T-IF board
(LINE-H line
of CONT-1
connector)
R11 on
C-IF
-10 dB/600 ohms
ALC signal
*Input to HANDSET/MIC
connector: 1500 Hz, -46 dBm,
600 ohms
*TX frequency: 25 MHz SSB
*Power data: 240
T/R ANT
connector
R76 on
TX FIL
1570: 150 W
2570: 250 W
Microphone
gain
*Input to HANDSET/MIC
connector: 1500 Hz, -55 dBm,
600 ohms
*TX frequency: 25 MHz SSB
*Power data: 240
T/R ANT
connector
R209
on
TX/RX
-1570:
about 40 W
-2570:
about 65 W
Fig.7.4.1 TX signal flow
Fig.7.4.2 shows proper microphone gain adjustment.
Low gain Proper gain High gain
Fig.7.4.2 Microphone gain adjustment
Peak power Peak power Peak power

Furuno FS-1570 Specifications

General

Brand	Furuno
Model	FS-1570
Category	Telephone
Language	English