CTCSS Signalling Processor
FX818
1.4
External Components
C1 22pF
C2 22pF
C3 100pF
C4 0.1µF
C5 100pF
C6 0.1µF
C7 Note 2
C8 0.1µF
±20%
±20%
±20%
±20%
±20%
±20%
±20%
±20%
R1 1M
R2 100k
R3 100k
R4 Note 2 ±10%
R5 22k ±10%
R6 Note 1 ±10%
±5%
±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:
R2
Tx Sub Audio Gain
= -
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:
R3
Gain
= -
R4
C7 x R4 should be chosen so as not to compromise the low frequency performance of this
product.
Figure 2 Recommended External Components
ã 1997 Consumer Microcircuits Limited
6
D/818/4
CMLMICRO [ CML MICROCIRCUITS ]
