Panasonic KX-FG2452CX Service Manual page 43

KX-FG2452CX
6.8.5. Line Amplifier and Side Tone Circuit
1. Circuit Operation
The reception signal output from the line transformer T101 is input to pin (6) of IC101 via C118, R125 and then the signal is
amplified at pin (7) of IC101 and sent to the reception system at 3dB.
The transmission signal goes through C730 and R732 and enters IC704-pin (6), where the signal is amplified to about 24dB.
Then, it is output from pin (7) of IC704 and transmitted to T101 via C117, R110 and R191. If the side tone circuit is not applied,
the transmission signal will return to the reception amplifier via C118 and R125. When the side tone circuit is active, the signal
output from IC704 pin (7) passes through C117, R113, R114, C112 and R112 and goes into the amplifier IC101 pin (5). This
circuit is used to cancel the transmission return signal.
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