Solid-state amps add years to communications system

TOBYHANNA ARMY DEPOT, Pa. - U.S. Army engineers have found a way to keep a large, aging communications system in the field for at least 15 years longer than expected by swapping out traveling wave tubes (TWTs) for solid-state amplifiers.

Jul 1st, 1997
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By John Keller

TOBYHANNA ARMY DEPOT, Pa. - U.S. Army engineers have found a way to keep a large, aging communications system in the field for at least 15 years longer than expected by swapping out traveling wave tubes (TWTs) for solid-state amplifiers.

The Digital European Backbone (DEB) is part of one of the world`s largest line-of-sight communications systems. It uses long- and short-range digital, microwave communications equipment to provide secure voice and data transmissions to U.S. commanders in Europe.

Electronics experts at the Tobyhanna Army Depot, Pa., who maintained the DEB system, traced ever-troublesome breakdowns to TWTs during an exhaustive study in the late 1980s, explains John MacCartney, an electronics mechanic at Tobyhanna.

"This system runs seven days a week, 365 days a year," MacCartney says. "We determined the big stumbling block to be the TWT. It was the biggest single point of failure. So we started looking at off-the-shelf commercial amplifiers to replace the TWTs because they were getting to the end of their lifecycles."

Tobyhanna specialists have almost completed a program to replace failed TWTs with solid-state amplifiers. This switch reduces power consumption and heat in the system, and each solid-state device has a mean-time-between-failure rating of 100,000 hours. "The other units weren`t lasting anywhere near that long," MacCartney says.

"The Army was looking at phasing this system out," he says. "Now we can run the system for another 15 years." Previous technology cost the Army about $11,000 to replace a TWT and amplifier, while the new solid-state amplifiers cost about $2,300 apiece, of which the Army has about 600 on order, MacCartney says.

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John MacCartney of the Tobyhanna Army Depot resets part of the Digital Radio and Multiplexer Acquisition test set, which is part of the a huge line-of-sight communications system in Europe.

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