CTCSS Signalling Processor
FX818
1.4
External Components
C1
C2
C3
C4
C5
C6
C7
C8
22pF
22pF
100pF
0.1µF
100pF
0.1µF
Note 2
0.1µF
±20%
±20%
±20%
±20%
±20%
±20%
±20%
±20%
R1
R2
R3
R4
R5
R6
1M
100k
100k
Note 2
22k
Note 1
±5%
±10%
±10%
±10%
±10%
±10%
X1
4.032MHz
±100ppm
Notes:
1. R2, R6 and C3 form the gain components for the Summing Amplifier. R6 should be chosen as
required from the system specification, using the following formula:
Tx Sub Audio Gain
=
−
R2
R6
2. R3, R4, C5 and C7 form the gain components for the Rx Input Amplifier. R4 should be chosen
as required by the signal level, using the following formula:
Gain
=
−
R3
R4
C7 x R4 should be chosen so as not to compromise the low frequency performance of this
product.
Figure 2 Recommended External Components
©
1997
Consumer Microcircuits Limited
6
D/818/4
CMLMICRO [ CML MICROCIRCUITS ]
