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The Selectone ST-32 Line Termination Panel is a small circuit board designed to interface most DC remote control consoles to the base station radio. When used as part of a DC remote control system, the ST-32 provides an economical way to optimize the location of radio transmitters or to provide low cost radio extensions within an office building or plant site.
Measuring only 2.6" L x 1.9" W x 1.0" H, the ST-32 is small enough to be mounted inside many radio base stations. The ST-32 is shipped with a modular RJ11 phone jack, a 7’ line cord, and a 42A wall mount terminal block. The ST-32 also comes with double-sided pressure sensitive tape for mounting and 18" color-coded flying leads for radio connections. Controls are provided for transmit and receive line levels. Form "C" relay contacts are provided for PTT, F1/F2 select, and Monitor.
- Compact Size – the smallest termination panel in the industry.
- Proven Design – thousands in daily use.
- Compatible – with most common DC control systems (+ transmit current; - monitor current).
- Easy to Install – includes modular jack, line cord, and terminal block for a professional installation.
- Two Year Warranty – backed by Selectone’s 20 years of service.
The ST-32 interfaces the base station radio to a single pair of metallic wires. It is then possible to transmit (two frequencies), receive (one frequency), and disable the tone protection (Monitor) by passing known DC currents to the ST-32 via the control wires. The same pair of wires is also used to pass transmit and receive audio between the radio equipment and the remote control equipment. Current detection is provided by optical isolators, while outputs are Form "C" relay contacts.
ST-32 OPERATING SPECIFICATIONS SPECIFICATION DETAIL GENERAL: Supply Voltage
13.6Vdc ±20% Supply Current
less than 60mAdc Temperature Range
-30°C to +60°C Signalling Format
Loop current sense Dimensions
1.9"W x 2.6"L x 1.0"H
(4.83cm x 6.60cm x 2.54cm)OUTPUTS: PTT
Open Collecor, 100mAdc @ 24Vdc, and single Form-C dry relay contacts Monitor
Single Form-C dry relay contacts Transmit F1/F2
Single Form-C dry relay contacts AUDIO: RECEIVER TO CONTROL LINE Input Z
Greater than 2K ohms as seen from the receiver output Line Output Z
600 ohms nominal at 1000Hz Frequency Response
±3dB, 300 to 3000Hz (1000Hz ref.) Line Output
Adjustable; minimum of 40mVrms receive audio required to produce 0dBm (600 ohms) AUDIO: CONTROL LINE TO TRANSMITTER Line Input Z 600 ohms nominal at 1000Hz; 2500 ohms dc resistance Frequency Response ±3dB, 300 to 3000Hz (1000Hz ref.) Transmit Output -20dBm (600 ohms) on control line required to produce 0.77mVrms (open circuit) to transmitter audio input (TX HI) Output Z Less than 2000 ohms (build-out resistors supplied for HI-Z mic. input circuits) Specifications and descriptions subject to change without notice
© 1999, Communications Specialists, Inc. All rights reserved.
Revision 6/24/99
Last updated July 12, 1999