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RTU-292 Operations Manual
2.8.6 RX LINE INPUT IMPEDANCE
The factory setting for the Receive Line input impedance is 600 Ohms, but if a high input
impedance for bridging is needed, the impedance may be set to approximately 47k Ohm. To
set to high impedance, move the jumper plug at JP2 from pins 1&2 (low, 600 ohms) to pins
2&3 (high, 47k ohms).
2.8.7 DIAL MODE
The dialing mode of the RTU-292’s internal telephone is set by internal dipswitch SW1-4. The
dial mode choices are DTMF and 10pps Pulse. DTMF should always be used if the RTU-292
is interfaced with a touch-tone (DTMF) capable telephone line. Note that, even when set for
pulse dialing, the RTU-292 can still send DTMF tones onto the phone line to control automated
systems such as voice mail. After a call has been placed, the user may press either the star (*)
or pound (#) key. The RTU-292 will then produce DTMF tones in response to keypad presses
from either the front panel keypad or a connected local phone set. Once the current call is
terminated, the RTU-292 will revert to the pulse dialing mode.
Table 2-6 Dial Mode
SW1-4 Dial Mode Selection
Off DTMF *
On Pulse (10 pps)
2.8.8 TELEPHONE RING VOLUME
The telephone ringer volume may be set to a comfortable level with internal adjustment R156.
If the ambient noise level in the RTU-292’s location makes it necessary to change the ringer
volume, rotate R156 clockwise to increase the volume and counterclockwise to decrease it.
2.8.9 FULL/HALF DUPLEX RADIO
In full duplex operation, the RTU-292 will simultaneously send transmit audio to the radio and
take in its receive audio. In half duplex operation, the radio receive audio is muted while the
radio is keyed. This prevents a radio sidetone audio feedback loop in radios with sidetone
audio. This feedback loop hampers RTU-292 VOX operation. (Sidetone audio is transmit
audio that is internally routed back into the receive audio when the radio is keyed, allowing the
radio operator to hear his transmission.)
The Full/Half Duplex selection is set by dipswitch SW2-8. The factory setting is SW2-8 On,
for Half Duplex, preventing the feedback loop. To set to Full Duplex operation (receive audio
not muted during transmit), set SW2-8 to Off. For Simplex Systems, use the Half Duplex
setting.
JPS Communications, Inc.
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