ON
REMOTE CONTROL
ACC-J1
ACC-J2
ACC-J4
ACC-J3
AMP-CONT
13.8V
+
-
AC
BAT
RF OUT
TX IN
RX IN
PPS-CONT TX OUT RX OUT
OFF
110/220V
13.8 VDC
External
Power Source
Series
Protection
Diode
Fuse
30A
Figure 7. RM125/RM125R Connections to DC Power Source
Installation Procedure
–
Radio with PPS Option
PPS Functions
The optional Pre-Selector/Post-Selector, PPS-100, supported as an option by the RM125/RM125R,
permits operation of collocated receivers and transmitters on frequencies separated by as little as
10%. The PPS operating frequency range is 1.60 to 29.99 MHz.
To use the PPS, order the RM125/RM125R with option G65. The connections between an
RM125/RM125R with option G65 and the PPS are shown in Figure 8.
When the G65 option is installed, the PPS is controlled by the RM125/RM125R through serial and
parallel ports and is automatically inserted by the RM125/RM125R in the signal path in accordance
with the operating mode:
•
In the receive mode, the PPS functions as a preselector, providing an additional front end
selectivity stage for the receive path of the RM125/RM125R. This reduces the receiver
desensitization and overload that would normally occur in the presence of strong adjacent RF
transmissions.
•
In the transmit mode, the PPS is used as a postselector. It attenuates spurious signals and
broadband noise in the driver transmit signal before it reaches the internal RF power amplifier,
thereby reducing interference to neighboring receivers.
In both modes, the PPS automatically tracks the RM125/RM125R operating frequency. Rapid tuning
makes the PPS suitable for Automatic Link Establishment (ALE) or Adaptive Applications.
During the power-up self-test, the PPS automatically switches to the bypass mode: in this mode, RF
signals pass directly through the PPS, without filtering, and therefore it does not interfere with system
operation. The PPS also switches to the bypass mode when the RM125/RM125R frequency is outside
the PPS operating range, 1.60 to 29.99 MHz.
In case excessive RF power is applied to the PPS, the PPS enters the RF overload protection mode: in
this mode, the PPS antenna port is disconnected, and the internal antenna input is short-circuited to
ground. This also protects the RM125/RM125R internal transceiver against overload.
The PPS is housed in a 1U high (1.75”) case intended for 19” rack mounting. Standard operation is
from 115 or 230 VAC, 50/60 Hz; the PPS can also be powered from 12 or 24 VDC sources.
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6888882V02
