Oki B4100 - Manual (Page 481)

40055101TH Rev.4 481 /
8) Return Loss Adjustment
The return loss adjustment is performed by the installed C-R networks corresponding to the
individual country. For adjusting the return loss, select the corresponding C-R network by
the designated DIP switch and adjust the return loss by changing the values of capacitors
and resistors.
The dip-switch set to ON corresponds to the country as shown in the table.
Country Dip-switch Symbol (network)
UK SW1-5 R29, C21, R26
Italy/Belgium SW1-6 R30, C22, R27
Denmark SW1-7 R31, C23, R28
Norway SW1-8 R76, C54, R77
9) AGC (automatic gain control)
AGC is a function for adjusting the sending and receiving levels automatically in accor-
dance with the line current values, so that the optimal communication level is automatically
set. The circuit section to determine the AGC characteristics is formed by resistors R41
and R43 connected to the AGC terminal of the speech IC. The AGC gain is high when the
resistor values are small, and the AGC gain is low when the resistor values are large.
10) Pulse Dialling
Changing the make-and-break ratio is determined by the dip-switch SW4-1 and 2.
• Setting SW4-1 to ON and SW4-2 to OFF corresponds to a 33% make ratio.
• Setting SW4-1 to OFF and SW4-2 to ON corresponds to a 40% make ratio.
11) MF dialling
The MF signal sending level is adjusted by the selection of resistors and capacitors
allocated for the individual countries by the dip-switch setting.
The dip-switch set to ON corresponds to the country as shown in the table below.
Country Dip-switch Symbol
UK SW2-1 C31, R38
Italy/Belgium SW2-2 C70, R39
Denmark SW2-3 C71, R80
Norway SW2-4 C72, R81
Rated Value
-9 dBm/-11 dBm
-6 dBm/-8 dBm
-9 dBm/-11 dBm
-9 dBm/-11 dBm
Increase the resistor value to lower the MF signal sending level, and decrease the resistor
value to raise the sending level. The difference between the high and low groups of the
MF signal is performed by changing the capacitance of the capacitor. The allowable level
difference between the high and low groups is (2
±
1) dB.
12) Manual Pad
The manual pad is used as a countermeasure by the ON setting of SW3-8 when howling is
occurs because of line conditions. (normally set to OFF)