Advertisement
TRC-70
22
CIRCUIT DESCRIPTION
*
Receiving front end protection circuit
The voltage (8 V) from 8R turns 0104 on, turns
Q103 on, (2SA1362(Y)), which then sets receiving se-
lect relay K116 on during reception.
Therefore, the
signal from the ANT terminal is sent to the RA terminal
via relay K116.
When a HF signa! exceeding approximately 10 W is
input to the ANT terminal during reception, forward
Li2?
C20)
waves are detected by D101.
This signal level is
enought to turn Q106 (2SC2712(Y)) on; which turns
Q105 (DTA144) off, then on. Q104 (DTD114EK) then
changes from on to off, and Q103 changes from on to
off. Thus, receiving select relay K116 is not activated,
so the high-frequency power is not fed to the RA ter-
minal to protect the receiving front end.
LI28
MIC terminal
See Figure 21 and Table 7.
mic @)
@ GND (MIC)
ss @®
© sPs
DOWN (@)
© 8m
GND
@ up
Fig. 21 MIC pin (Viewed from front panel)
Receiving front end protection circuit
Pin No. | Pin Name
Description
MIC
MIC impedance approx. 6002
SS)
STANDBY switch.
SPS
Receiving audio output.
GND {MIC)|
Ground for MIC.
GND
Ground.
QPE|@/@Q|C|O|O
Table 7 MIC pin description
Advertisement
