Copyright 1993 Link Communications
Theory of Operation:
The RLC-6 link expansion board is controlled by your existing repeater controller. 3 logical output lines are
required from that controller for total board control. These 3 lines are used to access the 8 modes that the RLC-6 has
programmed into it. When selecting the desired mode of operation, an active low signal is applied to the appropriate
control lines.
Incoming audio is immediately biased to 2.50V DC above ground. This gives the RLC-6 the ability to pass,
without peak clipping, 2.2V peak to peak input and output. Non-squelched audio can be used on the board. Audio
squelching is accomplished by the CMOS audio gate 4066. When either a valid COR is received or the link controller
chooses to accept the receiver's audio, the 4066 passes the audio. When the link controller chooses to disconnect a
receiver from the board's operation, its receiver's COR will not unsquelch the incoming audio. All audio enters its
transmitter's audio bus multiplexor. Each transmitter can be set to output any one of these audio sources.
Audio sources:
- LINK PORT 0
(MAIN RECEIVER INPUT)
- LINK PORT 1
- LINK PORT 2
- LINK PORT 3
- MIXED AUDIO
(MAIN,1,2,3 AUDIO MIXED (unless muted) )
Which source is selected is determined by EPROMs 1 and 2. For more info on the audio sources, see the description
of the modes.
Transmitter PTT:
The transmitter PTT outputs are implemented with the power MOSFET transistors (2N7000). These devices
are built to handle 100 mA of current. The RLC-6 provides an active low for the transmitter PTT circuitry, (this can
be changed if you have the RLC-6 Mode Editor). DO NOT EXCEED THE 100 mA RATINGS OF
THE PTT CIRCUIT OTHERWISE PERMANENT DAMAGE MIGHT OCCUR TO THE
2N7000.
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