7K • Appendix C
C-10
Control Receiver Audio
If you are adding a control receiver to your repeater system, you must supply
both a COR signal and an audio signal from the control receiver to the
controller. The COR signal has been previously discussed. Control Receiver
Audio should be connected to Pin #25 of J2 (the female DB25S connector),
shown in the schematics as RX3.
The design of the control receiver audio input is similarly to the design of the
repeater receiver audio input. Refer to the Repeater Receiver Audio section on
page C-6 for additional information. The control receiver level pot is R99.
• To increase the gain of the control receiver input stage, cut the lead labeled
“C” of resistor R37 (100K).
• To accommodate pre-emphasized audio, change capacitor C74 from 47pF
to 0.01µF if normal gain is used, or 0.0047µF if the high-gain modification
has been done.
After you have completed the control receiver audio interfacing, check the
audio level at Pin #8 of U37C. The level should be about 700mV RMS (2V p-p)
when the control receiver is fed a fully-deviated 1KHz sine wave tone from a
service monitor.
DC Power
The controller requires a power source of +12 to +15VDC.
Note: Do not exceed a supply voltage of +15V. The controller’s DC power
input is protected by a 15V transient suppressor, which will start to draw current
when the input voltage exceeds 15VDC.
The amount of current drawn by the controller depends upon the configuration.
• The 7K Main Board draws less than 125 mA.
• The Telephone Interface Module draws negligible current.
• The Speech Synthesis Module draws about 180 mA.
• A loaded system, then, can be expected to draw about 300 mA.
The controller does not require a regulated power source, since it contains
local voltage regulator ICs for its analog and digital circuits. However, The
power source must be free of “sags” that may occur, for example, when the
transmitter is keyed. If significant ripple is present on the power source output,
the ripple “peaks” must not exceed +15V. Ripple “valleys” must not fall below
+12V.
The controller contains circuitry to protect the data stored in memory during the
power outages. No external battery backup is needed to prevent loss of
memory data. Owners may wish to provide backup power to both the repeater
and the controller to ensure continuous service during utility power outages.
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