Ich zitiere mal das Fledermauslabor:

(.)
1 2 3
4 5 6
7 8 9
10 11 12

The () is ground around remote antenna centre pin.

1 EXT SPKR+
2 EXT SPKR-
3 DATA
4 EXT MIC
5 /WE
6 BUSY
7 OPT SEL*
8 OPT B+
9 KEY
10 KEYLOAD
11 DVP CLK/AUX TX
12

* The OPT SEL pin follows the following table:

All Internal, STD Operation 5VDC
EXT MIC and SPKR, STD ANT 1.24VDC
EXT MIC, SPKR and ANT 2.5VDC
EXT ANT ONLY 3.74VDC

According to the schematic, there is a 20 kohm resistor from REG +5VDC tied to the OPT SEL pin. This means that in order to select one of the above modes, you will need to tie the OPT SEL pin to ground through a zener diode(s)(and with no connection the pin floats to 5V which is STD operation).

Geht also.

MfG

Frank