Cimarron C Plus I, Service And Installation Manual, Page: 10 / 29

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SECTION 5 – Data Input - Details
Data input is the signal input to the C Plus. This is Receive Audio
from the radio. Data In + is the high side and Data In - is the low
side. Data input is jumper selectable for high impedance single
ended, high impedance balanced and 600 ohm balanced. In non-
balanced configurations, Data In - is referenced to ground.
However, note that it is not directly shorted to ground. In balanced
systems, it is signal return. Always attach an independent station
ground to the rear panel P3 pin 8 or P2 pin 10.
The input is capacitor coupled for DC blocking and is MOV
protected. When interfacing to a radio, connection should be
receive audio, before de-emphasis (flat audio). Data input + should
be jumped for high impedance and data input – should be jumped
to ground.
If connected to a balanced line, remove ground jumper JP-7.
Data input is AGC conditioned so generally, no adjustment is
necessary. A test point is provided for oscilloscope connection. If
the signal is clipped and distorted, a potentiometer and a bank of
gain jumpers can reduce gain. Alternately, if the signal is too weak,
gain can be increased.
Attenuation jumpers are described below. Use only one jumper at a
time.
Input Signal Attenuation Unbalanced Balanced
18 dB JP-13 JP-10
12 dB JP-12 JP-9
6 dB JP-11 JP-8