P S - 7 0 4 F O U R - C H A N N E L P O W E R S U P P L Y
2 - 2
LINE TERMINATION (REAR PANEL)
Switching of the channels’ terminations
on
and
off
are done with the rear-panel
toggle switches. In most systems, all terminations on the PS-704 should be in the
on
position (default setting). The fundamental concept of Clear-Com party-line
intercom is that all channels are terminated in one location, preferably at the
power supply.
Caution: All intercom lines must be terminated. Care must be taken not to
“double-terminate” a line. All unused intercom lines must also be
terminated.
The PS-704 provides terminations for each of its four channels. Clear-Com main
stations and power supplies provide switch-selectable termination networks on all
intercom lines. It is up to the user to ensure that the terminations are set
correctly. An unterminated line will cause excessive levels, possible oscillation of
line drivers, and severe imbalance of hybrid null networks. A line with double or
multiple terminations will cause low levels and severe imbalance of hybrid null
circuits.
If the PS-704 is the only power supply in the system (no other power supplies or
powered main stations are in the system) the termination switch on each channel
of the PS-704 should be switched to
on
. Simply toggle the rear-panel switch
labeled
term
to the
on
position. The termination switch should be set to the
off
position
only
if the channel is terminated at another station.
PROGRAM INPUT (REAR PANEL)
A 3-pin XLR female connector provides the main program input to the station.
This input level is controlled by the rear-panel
program level
control adjacent to
the
program in
connector. This control sets the overall level for all the channels.
The input accepts a balanced or unbalanced line-level audio signal. The program
can be fed to any or all of the intercom lines by using the front-panel toggle
switches labeled
program on/off
. There is one of these switches for each channel.
The pinout of the program input connector is as follows:
Pin #1 --- Ground (shield)
Pin #2 --- + Signal
Pin #3 --- - Signal
RACK MOUNTING
The unit requires 1.75 in. (44 mm or 1RU) of rack space. It requires no
additional free rack space above or below it for ventilation. The station is 7.5 in.
(165 mm) in depth and requires at least 2.5 in. (64 mm) clearance in the rear for
connectors and cables. The single-piece front panel has integral “rack ears.” This
adds stability and strength.
