PSD-4 AND PSD-8
6
3. Installation
3.1 Choosing a Site
• The PSD must be installed within five feet (1.5 m) of a grounded AC outlet.
• The PSD must be within 50 feet (15 m) of the equipment that will be attached to the main channel and
each sub-channel.
• Allow 36 inches (91 cm) frontal clearance for operating and maintenance accessibility.
• Allow four inches (10 cm) rear-panel clearance for the power and interface cables.
• Side-panel brackets can be used to install the unit in a 19" rack. (The brackets can be removed without
harming the PSD.)
3.2 Configuring the PSD Printed Circuit Board
Table 1 on the following page explains each of the configurable jumpers or switches on the PSD printed circuit
board. Figures 3 and 4 show the locations of each of the jumpers and switches for the PSD-4 and PSD-8.
There are two EXT. BUFFER switches on the PSD-8. These are extra buffers—not external buffers. Use the
extra buffers when the PSD is connected to equipment that cannot accept an external clock from the PSD.
The extra buffers compensate for phase differences between clocks. There are many applications where this
might be necessary, but one example would be where multiple CSU/DSUs (each attached to its own leased
line that provides clocking) are connected to the PSD.
Switch S1 controls the buffer for sub-channels 1 through 4, and switch S2 controls the buffer for sub-channels 5
through 8.
Figure 2. The front panels of the PSD-4 (top) and the PSD-8 (bottom).
POWER:
Lights when
the unit is
receiving
AC power
DATA:
Lights when
data is broadcast
from the main
channel to the
sub-channels
ACTIVITY:
Lights when the
sub-channel
accesses the
main channel.
AUTOMATIC:
Lights when sub-
channel has been
automatically
disabled.
SUB-CHANNEL
DISABLE:
Press in the push button
to manually disable a
sub-channel.