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Product Description

The Model 279 provides transparent conversion between fiber optic devices utilizing multi-mode fiber and those with single mode fiber. Single mode fiber can transmit data over much longer distances than is possible with multi-mode fiber. It accomplishes this by limiting the amount of power lost through leakage in the walls of the fiber and using 1300 nm wavelength emission which has less attenuation than 850 nm. Thus, this converter regenerates signal strength and is used to extend the distance far beyond the specification for multi-mode fiber. The Model 279 can also be used when the optical fiber type of the equipment is not compatible with the installed fiber optic cable.

Features of the Model 279 include the ability to operate from DC to 2.5 MBPS. This allows a variety of applications to take advantage of the transmission capability of the device and fiber cable. A loss budget of 15 dB is provided which equates to a distance of approximately 20 kilometers. Since operation is allowed at DC there is no clocking information which the Model 279 could user to perform automatic gain control. Therefore the gain is user controlled by a Line Loss switch and once set does not have to be changed. Once the single mode line is installed it length is fixed. Four positions on the Line Loss switch allow selection of two, five, ten and 15 dB of loss. Four LED’s are provided to give a visual indication of the selected line loss. Applications for the Model 279 are varied from those that use the device as an individual converter to those that use a pair of converters as single mode line drivers to cover long distances. Since the Model 279 may not always be used in pairs a phase switch is included which provides the ability to reverse the phase between the multi-mode ports and the single mode ports.


The Model 279 is powered by a wall mounted DC adapter which develops 12V. By use of an internal DC-to-DC converter the user can supply any DC voltage from +8V to +36V for those situations where AC is not available. The fiber optic ports of the Model 279 are provided on ST connectors. The product is designed for inline mounting. Its relatively small size allows for placement in virtually any installation.

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