Telephone-Line Boosters, Micro Seven's model LS15-A3 and LS15-A4




Micro Seven's Telephone Line Boosters, models LS15-A3 and LS15-A4 provide isolation between two telephone lines with higher loop current, higher loop voltage, and powerful ring signal (only for LS15-A3). When PBX equipment does not have capability to drive long distance telephone cables to telephones, modems, and fax machines because of lower loop voltage and low-power ring signal, models LS15-A3 and LS15-A4 are inserted at PBX equipment. There are two RJ11-C connectors on LS15-A3 and LS15-A4. The line 1 is connected to CPE, and line 2 is connected to PBX.

The models LS15-A3 and A4 are operated by different types of AC/DC adapters. A 220V version of AC/DC adapter is available as an option for LS15-A3. The LS15-A3 and -A4 are caller-ID compatible so that caller-ID data is passed to CPE.





Dialing from Line 1 (CPE interface) to Line 2 (PBX interface):

Rotary-pulse and DTMF dialing


Input characteristics at PBX (Line 2):

Input impedance at 1 k Hz: 600 ohms

Signal Bandwidth: 300 HZ to 3 k HZ

Signal Range: -45 to +5 dBm

Component: Telephone coupling transformer, relay, and optical-coupler


Battery-feed voltage (loop voltage) at Line 1, CPE interface: -42 volts nominal


Loop current at Line 1 (CPE interface): 25 mA


Ring Signal at Line 1 (CPE interface):

LS15-A3: 20 +/- 2% Hz sine wave. 250 Volt peak-to-peak with source resistor of 1.6k ohm


Note: model LS15-A4 passes same ring signal from Line 2 (PBX interface) to Line 1 (CPE interface).


Line Input Jacks for Line 1 and 2: USOC-RJ11-C, standard modular phone jacks


Power Switch: on when the switch is pushed in, off when the switch is pushed out.


Power Indicator: green LED display


AC/DC Adapter: 117VAC +/- 5%, or 230VAC +/- 5%(for optional 230V AC/DC Adapter available for LS15-A3). Models LS15-A3 and LS15-A4 use different types of AC/DC adapters.


DC input for LS15-A3: 12VDC unregulated, 800mA maximum


DC input for LS15-A4: 48VDC unregulated, 150 mA maximum


Caller-ID compatibility: Caller-ID signal that is received from PBX side is passed to CPE side for both Bellcore and ETS modes.


Line Status Display for Line 1 (CPE interface) and Line 2 (PBX interface): red LED for each line to indicate off-hook status (continuous on) or ringing status (blinking). There is no blinking LED display for model LS15-A4 at Line 1.


Calibration: not required


Dimensions: 19 cm (4") W x 4.5 cm (1.75") H x 10 cm (7.5") L


Weight: 400g (0.8 lbs.)


Environmental: Operating temperature: 0 to 40 degree C, Humidity: 85% RH at 40 degree C


Warranty/Service: 6 months limited warranty. No warranty if any factory seal is broken. Service is performed at the factory, usually within 5 working days.


Options and Accessories:

230V input AC/DC Adapter (117V input unit is a standard.)


Country of Origin: Manufactured in United States of America

Front-panel Description


The front panel of LS15-A3 or A4 is shown in Figure 3-1.

1. J1 (RJ11-C): Line 1 Input Jack for connection to CPE

2. Line 1 OH/BUSY Indicator: LED to indicate "Off Hook" status or "Line busy" condition. It blinks when it is ringing.

3. J2 (RJ11-C): Line 2 Input Jack for connection to PBX

4. Line 2 OH/BUSY Indicator: steady LED on to indicate continuous loop current. It blinks when it receives ring signal.

5. Power ON (when the switch is in.) or OFF (when the switch is out).

6.Power LED: on when the power is on.


Figure 3-1 Front Panel of LS15-A3 and LS15-A4

Rear Panel Description


The rear panel of LS15-A3 is shown in Figure 3-2. Connect AC/DC Adapter or Car Battery Adapter to a DC Input connector on the rear panel. The rear panel of LS15-A4 shows power input requirement of 48V DC input, 150 max.


Figure 3-2 Rear Panel of LS15-A3