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970Re: [coldwarcomms] Re: PA L3I cable

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  • Mark Foster
    Jun 1, 2000
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      At 04:05 PM 6/1/2000 -0400, you wrote:
      > At the risk of asking the world's stupidest question, did the
      >conversion of L3 (and maybe L4) routes to L5 repeaters always involve
      >adding additional repeaters and cable vaults every mile (versus every 4
      >miles) or did they sometimes just replace the repeaters in the L3 huts
      >with much newer designs (based on L5 technology) and live with the
      >reduced bandwidth that operating with 4 mile spacing would require ? I
      >should think that adding lots of cable vaults in at least some places
      >would have been very expensive and more or less a nightmare... whilst
      >changing the repeaters would have been pretty easy and cheap.
      >
      > Also what was the time frame for the conversion to L5 ? I should
      >suppose that by about 1985 at the latest it would have been clear that putting
      >additional money into L coax made no sense with fiber becoming a proven
      >and cheaper technology...

      Believe it or not. The Chesterfield to Littleton route was converted to
      L-5E (enhanced)
      in 1990. One year later the route was shut down and Chesterfield abandoned.

      Typical LCXR systems are shown below

      TYPE DATE BANDWIDTH TUBES
      REPEATER SPACING CAPACITY
      -1 1941 3
      mhz 4 8
      miles 600 voice circuits
      L-2 1942 840
      khz 4 16
      miles 360 voice circuits *
      L-3 1953 8
      mhz 8 4
      miles 5,580 voice circuits
      L-3 (Improved) 1960 8
      mhz 12 2
      miles 9,300 voice circuits
      L-4 1967 17
      mhz 20 2
      miles 32,400 voice circuits
      L-5 1972 57
      mhz 22 1
      mile 108,000 voice circuits

      L-4 and L-5 systems were transistorized are required very little repeater
      maintenance compared to previous systems. I believe a TD-2 system had a
      capacity of 19,800 voice circuits. If fiber had not come along LCXR was
      not so bad.
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