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x21 modem eliminator picture

Features / Benefits

  • Interface - ITU X.21 (DB-15 Female Connectors, V.11 electrical
  • Data Rates - Synchro- nous up to 2.048Mbps
  • FPGA design allows very low jitter at high end speeds
  • Options for Control / Indicate delay, on a per port basis
  • Status LED's for each port allows ease of connection and trouble shooting
  • 110/22VAC switch selectable
  • Sturdy Metal Enclosure


The SME-X21 modem eliminator allows two X.21 DTE devices to communicate within proximity of each other. The SME-X21 transmits data bi-directionally at data rates up to 2.048Mbps between DTE devices. All clocking and signal crossover are provided within the SME-X21. The unit is equipped with two DB-15 female connectors.

The SME-X21 is an excellent choice for interconnecting your LAN or mainframe equipment. Substantial cost savings are derived by eliminating the need for analog or digital Modems.

Installation is fast and simple by setting the internal switches for Clocking and Control (C) to Indicate (I) delay. The SME-X21 has status LED's for each attached DTE device which allows the user to visually confirm the presence of control signals.

The SME-X21 utilizes state of the art digital CMOS technology to provide a feature filled product at a very affordable price. Our Field Programmable Gate Array (FPGA) design has allowed us to offer this product with a wide selection of user Baud Rates. This design approach has also reduced the amount of clock jitter for high speed 2.048Mbps transmissions.

The SME-X21 is housed in a sturdy metal enclosure and operates on 110/220VAC. Typical MTBF figures are in excess of 100,000 hours of operation.

The SME-X21 has a three year warranty and a 24 hour turnaround on warranty repairs.

The X.21 Modem eliminator network diagram


Application The modem eliminator  allows interconnection of two X.21 DTE (Terminal) devices located within proximity of each other
Capacity Two (2) X.21 DTE's

X.21 using V.11 electrical specification

Data Rates Up to 2.048Mbps
Channel Interface Two Female DB-15 Connectors
Surge Protection Main power supply
Power Source 100-120 to 200-220VAC @10%, 50/60Hz, 0.16/0.08A, external 110/220 volt select switch, IEC Power Inlet, (2) 5mm Fuses
Environmental Operating Temperature....32º to 122º F (0º to 50º C)
Relative Humidity.............5 to 95%
Altitude............................0 to 10,000 feet
Dimensions Height ....... 1.75 inches (4.44 cm)

Width ........ 7.90 inches (20.07 cm)

Length ....... 9.00 inches (22.86 cm)

Weight 2 pounds (0.914Kg
Warranty Three Years, Return to Factory
Ordering Information: Model: SME-X21
Description: Synchronous X.21 Modem Eliminator
Included with each unit: 1) Operations Manual

2) U.S.A. Grounded Power Cord, Part #713015

3) Optional Power Cords

..... A) United Kingdom, Part #713016

..... B) Continental Europe, Part #713017

..... C) Other: Specify Country on Purchase Order

Optional Accessories: 1) Spare Data Center Fuses

..... A) 160ma Fuse, Qty (2) Part #714000

..... B) 80ma Fuse, Qty (2) Part #714001