SPLITTING HAIRS TO SPEED CALLS (Jun, 1954)

SPLITTING HAIRS TO SPEED CALLS

To triple the voice-carrying capacity of coaxial cable, Bell Laboratories engineers had to create new amplifying tubes with the grid placed only two-thirds of a hairs breadth from the cathode. Furthermore, the grid wires had to be held rigidly in position; one-quarter of a hairs shifting would cut amplification in half.

Working with their Bell System manufacturing partners at Western Electric, the engineers developed precise optical means for measuring critical spacing insulators. On a rigid molybdenum grid frame they wound tungsten wire three ten-thousandths of an inch thick. To prevent the slightest movement they stretched the wire under more tension for its size than suspension bridge cables, then bonded it to the frame by a new process.

The resulting tube increases coaxial’s capacity from 600 to 1800 simultaneous voices —another example of how Bell Telephone Laboratories research helps keep your telephone system growing at the lowest possible cost.

BELL TELEPHONE LABORATORIES

IMPROVING TELEPHONE SERVICE FOR AMERICA PROVIDES CAREERS FOR CREATIVE MEN IN SCIENTIFIC AND TECHNICAL FIELDS

3 comments
  1. Toronto says: July 23, 201210:43 am

    1954 was also the year TI made the first silicon transistor. I’m pretty sure coax amps were transistorized by 1960. Nevertheless, this is a cool synergy of about 4 different technologies in one package.

  2. DocScience says: July 23, 201211:52 am

    There are few companies with the impact on global progress equal to that of Bell Telephone/AT&T.

    It’s hard to imagine a world of electronics without them. The loss of Bell Labs was a tragic byproduct of freeing telecom from monopoly.

  3. quadibloc says: July 23, 201211:33 pm

    This reminds me of something I recently read about IBM’s problems in convincing its suppliers to make more reliable vacuum tubes for it.

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