Because RFL™ and Hubbell® have a policy of continuous product improvement, we reserve the right to change designs and specifications without notice.
6.2 SPECIFICATIONS
Crystal Frequency:
The frequency of crystal clock oscillator Y1 is 3.584 MHz ± 50 ppm.
6.3 THEORY OF OPERATION
The 9785 AM Logic module circuitry is described in the following paragraphs. Refer to the block
diagram shown in Figure 6-2 and the schematic diagram shown in Figure 6-4.
6.3.1 INPUT KEYING CONTROL LOGIC
The 9785 AM Logic Module receives its input from the rear panel I/O and modules in the RFL 9785
terminal. It generates output for the transmitter and receiver detector modules based on switch settings
and input signals.
The START and STOP signals are present at edge connector pins B21 and C22 respectively where
they are buffered and filtered. Both of these signals are polarized by Switch SW1-1 depending on
whether normally energized or de-energized input relays are required for the application. An active
START input will generate a logic high output signal unless the STOP is active. A STOP command
has priority over a START command. The resulting logic high output is combined with other possible
sources of carrier start. These include DIRECT KEY, TEST-SWITCH (SW12), RESERVE KEY, and
CHECKBACK KEY. Any of these will generate a logic low SEND signal initiating carrier start.
START indicator DS3 and STOP indicator DS4 provide a visual indication when their corresponding
inputs are active. An active START input will generate a logic high START-OUT output signal at
edge connector pin B26. An active STOP input will generate a logic high STOP-OUT output signal at
edge connector pin A26.
The logic low SEND signal is inverted and available on edge connector pin B27 as a logic high
UTILITY-OUT output signal.
The logic low RESERVE KEY input starts the carrier as noted above, and also sends a logic low
RESERVE-OUT signal to the transmitter module to set the reserve signal level. A logic high
CHECKBACK-LEVEL input can also set the reserve signal level. A START command has priority
over RESERVE KEY and CHECKBACK-LEVEL inputs. The reserve signal level is overridden.
RFL 9785 RFL Electronics Inc.
February 7, 2007 6-2 (973) 334-3100
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