Loading ...
Sorry, an error occurred while loading the content.
 

Re: [coldwarcomms] Re: Voltages

Expand Messages
  • David
    The positive voltage one end, negative on the other, trick has been around since at least the early days of Trans-Atlantic cables. The repeaters are in series
    Message 1 of 19 , Mar 2, 2011
      The positive voltage one end, negative on the other, trick has been around
      since at least the early days of Trans-Atlantic cables. The repeaters are
      in series DC-wise, so the first one works on {say} neg 1500 to neg 1400
      volts. The second one was neg 1400 to neg 1300, etc. And the repeaters were
      designed to fail open; when they did, the entire 3000 volts appeared across
      it...and jumped a gap designed to melt shorted, restoring the cable with
      one repeater-worth less gain.

      (Obviously L-4 and T-1 repeaters are easier to access for repair than a
      Trans-Atlantic cable one.)

      I'm surprised L-3 used AC...

      You used to see N2 cylinders on every third GTE pole until they got their
      act together & started fixing the leaks. But that was POTS; I guess
      L-carrier could use that as well. At Garden City, there was a conventional
      gas meter on the dry air plant. It was to measure air used by the cable and
      thus show there's a leak; as normally it would not move.
    • charlie Fargis
      if that meter was at 5301 N 22nd street it did when I was there. On the Pentagon voice pair cable. All the time due to Metro construction To:
      Message 2 of 19 , Mar 2, 2011
        if that meter was at 5301 N 22nd street it did when I was there.
        On the Pentagon voice pair cable. All the time due to Metro construction

        To: coldwarcomms@yahoogroups.com
        From: wb8foz@...
        Date: Wed, 2 Mar 2011 17:19:18 -0500
        Subject: Re: [coldwarcomms] Re: Voltages






























        The positive voltage one end, negative on the other, trick has been around

        since at least the early days of Trans-Atlantic cables. The repeaters are

        in series DC-wise, so the first one works on {say} neg 1500 to neg 1400

        volts. The second one was neg 1400 to neg 1300, etc. And the repeaters were

        designed to fail open; when they did, the entire 3000 volts appeared across

        it...and jumped a gap designed to melt shorted, restoring the cable with

        one repeater-worth less gain.



        (Obviously L-4 and T-1 repeaters are easier to access for repair than a

        Trans-Atlantic cable one.)



        I'm surprised L-3 used AC...



        You used to see N2 cylinders on every third GTE pole until they got their

        act together & started fixing the leaks. But that was POTS; I guess

        L-carrier could use that as well. At Garden City, there was a conventional

        gas meter on the dry air plant. It was to measure air used by the cable and

        thus show there's a leak; as normally it would not move.


















        [Non-text portions of this message have been removed]
      • Tad G
        Here s the Garden City meter setup: http://tad.grosvenor.org/gallery/d/46340-2/IMG_1795.jpg More at:
        Message 3 of 19 , Mar 2, 2011
          Here's the Garden City meter setup:
          http://tad.grosvenor.org/gallery/d/46340-2/IMG_1795.jpg

          More at:
          http://tad.grosvenor.org/gallery/v/Miscellaneous/GardenCity/

          -Tad

          ----- Original Message -----
          From: "David" <wb8foz@...>
          To: coldwarcomms@yahoogroups.com
          Sent: Wednesday, March 2, 2011 5:19:18 PM
          Subject: Re: [coldwarcomms] Re: Voltages


          The positive voltage one end, negative on the other, trick has been around
          since at least the early days of Trans-Atlantic cables. The repeaters are
          in series DC-wise, so the first one works on {say} neg 1500 to neg 1400
          volts. The second one was neg 1400 to neg 1300, etc. And the repeaters were
          designed to fail open; when they did, the entire 3000 volts appeared across
          it...and jumped a gap designed to melt shorted, restoring the cable with
          one repeater-worth less gain.

          (Obviously L-4 and T-1 repeaters are easier to access for repair than a
          Trans-Atlantic cable one.)

          I'm surprised L-3 used AC...

          You used to see N2 cylinders on every third GTE pole until they got their
          act together & started fixing the leaks. But that was POTS; I guess
          L-carrier could use that as well. At Garden City, there was a conventional
          gas meter on the dry air plant. It was to measure air used by the cable and
          thus show there's a leak; as normally it would not move.





          ------------------------------------

          Yahoo! Groups Links
        • ajbtelecom
          I realize that Tom s original question dealt with coax systems, but the mention of T1 repeater powering with -130 VDC provides a good opportunity for me to go
          Message 4 of 19 , Mar 4, 2011
            I realize that Tom's original question dealt with coax systems, but the mention of T1 repeater powering with -130 VDC provides a good opportunity for me to go on a tangent.

            On a _real_ T1 carrier trunk, -130 volts DC was placed on the 4-wire trunk across the transmit and receive pairs "in simplex," the same way a "phantom" circuit was derived. This involved feeding one side of the DC supply on each pair at the exact [electrical] midpoint of the terminating impedance of the pair. In the past, this would be a center tap on a repeat coil, but on modern equipment the termination and power feed is all done using solid-state components. For a very detailed explanation of the concept of derived ["phantom"] circuits, refer to the venerable tome "Principles of Electricity as Applied to Telephone and Telegraph Work," aka the AT&T Big Green Bible.

            Now days, when you order a T1 over copper, it is almost always delivered using HDSL. On a 4-wire HDSL circuit [HDSL4], the "phantom" technique is still used, but instead of 0 volts on one pair and -130 volts on the other, the voltages are typically something like -6 volts on one side and -190 volts on the other, yielding a net voltage of -184 VDC or thereabouts. A 2-wire HDSL circuit [HDSL2] puts the -6 and -190 right on the single pair. The use of negative voltages for both sides of the circuit is done in order to keep all the copper at negative potential in relation to earth, and by extension the atmosphere, which makes the copper more resistant to destructive corrosion.

            This brings us to "conditioning." While the primary purpose of the DC feed is to power repeaters and/or the line card at the remote end, it is also standard practice to have this voltage present even in a short-haul circuit with no repeaters. This is referred to as "sealing" or "conditioning" current, and it is done to prevent corrosion at joints. The default setting for modern line cards is to loop the sealing current all times, whether repeaters are present or not, and even if the circuit is inactive or "turned down." The common term for this is a "wet" trunk or pair, as opposed to a "dry" circuit, i.e., no sealing current.

            Thank you for bearing with me, I tend to go on tangents.

            Jim
            **************************************************
            Speaking from a secure undisclosed location.

            --- In coldwarcomms@yahoogroups.com, "John K Scoggin Jr \(W3JKS/AAT3BF\)" <aat3bf@...> wrote:
            >
            > IIRC, even T-1 circuits had + and/or - 130VDC on the pairs for repeater
            > power.
            >
          • David
            ... I was not aware of HDSL4; various craft folks have told me they still use conventional T1 for longer runs with repeaters. But I know it interferes with
            Message 5 of 19 , Mar 4, 2011
              On 3/4/11 3:35 PM, ajbtelecom wrote:

              > On a 4-wire HDSL circuit [HDSL4], the "phantom" technique is still used,
              > but instead of 0 volts on one pair and -130 volts on the other, the
              > voltages are typically something like -6 volts on one side and -190
              > volts on the other, yielding a net voltage of -184 VDC or thereabouts. A
              > 2-wire HDSL circuit [HDSL2] puts the -6 and -190 right on the single
              > pair. The use of negative voltages for both sides of the circuit is done
              > in order to keep all the copper at negative potential in relation to
              > earth, and by extension the atmosphere, which makes the copper more
              > resistant to destructive corrosion.

              I was not aware of HDSL4; various craft folks have told me they still use
              conventional "T1" for longer runs with repeaters. But I know it interferes
              with ADSL. Can you chain HDSL4 repeaters now?

              Interesting on the -6v as I've never seen this. I have ..encountered... the
              -130 (or so..) more than once.

              Note the Transatlantic cables used positive on one end to double the
              voltage drop available, hence the number of repeaters. An excellent book on
              their history was written by no less then Arthur C. Clarke: How the World
              Was One: Turbulent History of Global Communications.

              Sealing current is one of those things that many know exist and few
              understand. Years ago, I had an email exchange with a Bell Labs engineer
              who was the expert on it. It has to do with burning away microscopic
              whiskers that grow at the joints. More than that I don't recall, but it did
              not take much current to make major differences.
            • v6fiero@yahoo.com
              Right before I retired as a HiCap tech 2 years ago we were using double doublers on HDSL4 that extended the loop to about 15kFt on 22ga copper. Sent via
              Message 6 of 19 , Mar 4, 2011
                Right before I retired as a HiCap tech 2 years ago we were using "double doublers" on HDSL4 that extended the loop to about 15kFt on 22ga copper.
                Sent via BlackBerry by AT&T

                -----Original Message-----
                From: David <wb8foz@...>
                Sender: coldwarcomms@yahoogroups.com
                Date: Fri, 04 Mar 2011 16:46:22
                To: <coldwarcomms@yahoogroups.com>
                Reply-To: coldwarcomms@yahoogroups.com
                Subject: Re: [coldwarcomms] Re: Voltages

                On 3/4/11 3:35 PM, ajbtelecom wrote:

                > On a 4-wire HDSL circuit [HDSL4], the "phantom" technique is still used,
                > but instead of 0 volts on one pair and -130 volts on the other, the
                > voltages are typically something like -6 volts on one side and -190
                > volts on the other, yielding a net voltage of -184 VDC or thereabouts. A
                > 2-wire HDSL circuit [HDSL2] puts the -6 and -190 right on the single
                > pair. The use of negative voltages for both sides of the circuit is done
                > in order to keep all the copper at negative potential in relation to
                > earth, and by extension the atmosphere, which makes the copper more
                > resistant to destructive corrosion.

                I was not aware of HDSL4; various craft folks have told me they still use
                conventional "T1" for longer runs with repeaters. But I know it interferes
                with ADSL. Can you chain HDSL4 repeaters now?

                Interesting on the -6v as I've never seen this. I have ..encountered... the
                -130 (or so..) more than once.

                Note the Transatlantic cables used positive on one end to double the
                voltage drop available, hence the number of repeaters. An excellent book on
                their history was written by no less then Arthur C. Clarke: How the World
                Was One: Turbulent History of Global Communications.

                Sealing current is one of those things that many know exist and few
                understand. Years ago, I had an email exchange with a Bell Labs engineer
                who was the expert on it. It has to do with burning away microscopic
                whiskers that grow at the joints. More than that I don't recall, but it did
                not take much current to make major differences.









                [Non-text portions of this message have been removed]
              • David
                ... Interesting. But one of T1 s strengths is you can string repeaters. It seems to me that the jitter limit is 150 miles; at 6kft per repeater, that s a lot
                Message 7 of 19 , Mar 4, 2011
                  On 3/4/11 5:01 PM, v6fiero@... wrote:

                  > Right before I retired as a HiCap tech 2 years ago we were using "double
                  > doublers" on HDSL4 that extended the loop to about 15kFt on 22ga
                  > copper.


                  Interesting. But one of T1's strengths is you can string repeaters. It
                  seems to me that the jitter limit is 150 miles; at 6kft per repeater,
                  that's a lot of roadside cans.
                • John K Scoggin Jr (W3JKS/AAT3BF)
                  Back in the day , one of the issues you could have with repeatered T-1 circuits was oscillation when the data had marginal one s density. I recall spending
                  Message 8 of 19 , Mar 4, 2011
                    "Back in the day", one of the issues you could have with repeatered T-1
                    circuits was oscillation when the data had marginal one's density.



                    I recall spending two days (I was the customer, worked for the local power
                    company) watching the local Bell guys pumping manholes and replacing cans
                    until we found the offending unit. Lots of fun! Swap till ya drop. (Which
                    is why the 3 in 24 pattern was added to bit error rate test sets. We
                    couldn't find the problem using pseudo-random. Fortunately I had a "new"
                    pair of test sets with programmable patterns.)



                    Ahh, the fun we had! It was fun to be an early adopter. :-)



                    john



                    _____________________________________



                    John K Scoggin, Jr. W3JKS/AAT3BF/AAM3EDE/AAM3RE/AAA9SL
                    US Army Military Auxiliary Radio System
                    Delaware Gateway Station AAB3DE
                    Special Consultant - Technology

                    Emergency Operations Officer - DE and Region 3
                    "Old RADEF Officers never die, they simply decay exponentially."


                    Chief Engineer
                    Mobile Communications Unit 37 (AAT3CAD/W3MCU)

                    http://www.armymars.net/ArmyMARS/MCU <http://www.armymars.net/>


                    ARRL Assistant Section Manager - Delaware

                    Member, AMSAT and Radio Society of Great Britain
                    Email: aat3bf@...
                    Telephone: (302) 451-5000



                    "There is a very fine line between a hobby and mental illness ..." - Dave
                    Barry



                    _____

                    From: coldwarcomms@yahoogroups.com [mailto:coldwarcomms@yahoogroups.com] On
                    Behalf Of David
                    Sent: Friday, March 04, 2011 5:40 PM
                    To: coldwarcomms@yahoogroups.com
                    Subject: Re: [coldwarcomms] Re: Voltages





                    On 3/4/11 5:01 PM, v6fiero@... <mailto:v6fiero%40yahoo.com> wrote:

                    > Right before I retired as a HiCap tech 2 years ago we were using "double
                    > doublers" on HDSL4 that extended the loop to about 15kFt on 22ga
                    > copper.

                    Interesting. But one of T1's strengths is you can string repeaters. It
                    seems to me that the jitter limit is 150 miles; at 6kft per repeater,
                    that's a lot of roadside cans.





                    [Non-text portions of this message have been removed]
                  • David
                    ... I read up on the history of it; it goes back to 1962, yes JFK era. And the original repeaters had to use those new things called transistors. They had to
                    Message 9 of 19 , Mar 4, 2011
                      On 3/4/11 5:47 PM, John K Scoggin Jr (W3JKS/AAT3BF) wrote:

                      > "Back in the day", one of the issues you could have with repeatered T-1
                      > circuits was oscillation when the data had marginal one's density.

                      I read up on the history of it; it goes back to 1962, yes JFK era. And the
                      original repeaters had to use those new things called transistors. They had
                      to work over the usual -40F to 120 or whatever, and with little power and
                      space, etc.

                      And that tendency to oscillate was a major problem because one singing
                      repeater would wipe out adjacent T1's. Ooops....

                      That was why there's the bit density mandate; to avoid oscillations. And
                      that's why there were closed circuit loopback jacks and now SmartJacks that
                      fall back to making traffic. I suspect current repeaters are far more
                      stable; we've learned a lot in the intervening years.
                    • widebandit
                      Ah... And hot HDSL dead wood is such a wonderful thing to come into contact with when reaching for jumpers on the vertical side of the MDF...
                      Message 10 of 19 , Mar 4, 2011
                        Ah... And 'hot' HDSL dead wood is such a wonderful thing to come into contact with when reaching for jumpers on the vertical side of the MDF...

                        >
                        > I realize that Tom's original question dealt with coax systems, but the mention of T1 repeater powering with -130 VDC provides a good opportunity for me to go on a tangent.
                        >
                        > On a _real_ T1 carrier trunk, -130 volts DC was placed on the 4-wire trunk across the transmit and receive pairs "in simplex," the same way a "phantom" circuit was derived. This involved feeding one side of the DC supply on each pair at the exact [electrical] midpoint of the terminating impedance of the pair. In the past, this would be a center tap on a repeat coil, but on modern equipment the termination and power feed is all done using solid-state components. For a very detailed explanation of the concept of derived ["phantom"] circuits, refer to the venerable tome "Principles of Electricity as Applied to Telephone and Telegraph Work," aka the AT&T Big Green Bible.
                        >
                        > Now days, when you order a T1 over copper, it is almost always delivered using HDSL. On a 4-wire HDSL circuit [HDSL4], the "phantom" technique is still used, but instead of 0 volts on one pair and -130 volts on the other, the voltages are typically something like -6 volts on one side and -190 volts on the other, yielding a net voltage of -184 VDC or thereabouts. A 2-wire HDSL circuit [HDSL2] puts the -6 and -190 right on the single pair. The use of negative voltages for both sides of the circuit is done in order to keep all the copper at negative potential in relation to earth, and by extension the atmosphere, which makes the copper more resistant to destructive corrosion.
                        >
                        > This brings us to "conditioning." While the primary purpose of the DC feed is to power repeaters and/or the line card at the remote end, it is also standard practice to have this voltage present even in a short-haul circuit with no repeaters. This is referred to as "sealing" or "conditioning" current, and it is done to prevent corrosion at joints. The default setting for modern line cards is to loop the sealing current all times, whether repeaters are present or not, and even if the circuit is inactive or "turned down." The common term for this is a "wet" trunk or pair, as opposed to a "dry" circuit, i.e., no sealing current.
                        >
                        > Thank you for bearing with me, I tend to go on tangents.
                        >
                        > Jim
                        > **************************************************
                        > Speaking from a secure undisclosed location.
                        >
                        > --- In coldwarcomms@yahoogroups.com, "John K Scoggin Jr \(W3JKS/AAT3BF\)" <aat3bf@> wrote:
                        > >
                        > > IIRC, even T-1 circuits had + and/or - 130VDC on the pairs for repeater
                        > > power.
                        > >
                        >
                      • Mike O'Dell
                        I suspect you were running AMI signaling. B8ZS makes the ones density problem less severe a constraint. this matters a *lot* when you are running synchronous
                        Message 11 of 19 , Mar 4, 2011
                          I suspect you were running AMI signaling. B8ZS makes the ones density
                          problem
                          less severe a constraint. this matters a *lot* when you are running
                          synchronous
                          data over a T1 instead of channel bank frames. without B8ZS, a
                          particular bit
                          pattern in a packet can interfere pathologically with the line coding,
                          blowing synchronization out of the water.

                          this problem also happens on optical SONET links using POS -
                          Packet-over-SONET
                          coding. the original spec for POS didn't include a scrambler before the data
                          was put into the SONET frames. The "right" bit pattern in a packet would
                          likewise destroy frame synchronization, causing much tearing of hair and
                          gnashing
                          of teeth. the solution was to put a payload bit stream through a
                          scrambler so that
                          it was essentially impossible to create the degeneracy. I chaired the
                          meeting
                          at the Memphis IETF where the boffins from Lucent and Alcatel and
                          Siemens and
                          Fujitsu were all arguing over which polynomial was adequate to guarantee
                          immunity.
                          turns out the Lucent had already implemented something in their kit so
                          they were
                          *very* insistent that theirs be adopted. it was a long afternoon. sigh.

                          -mo


                          On 3/4/11 5:47 PM, John K Scoggin Jr (W3JKS/AAT3BF) wrote:
                          > "Back in the day", one of the issues you could have with repeatered T-1
                          > circuits was oscillation when the data had marginal one's density.
                          >
                          >
                          >
                          > I recall spending two days (I was the customer, worked for the local power
                          > company) watching the local Bell guys pumping manholes and replacing cans
                          > until we found the offending unit. Lots of fun! Swap till ya drop. (Which
                          > is why the 3 in 24 pattern was added to bit error rate test sets. We
                          > couldn't find the problem using pseudo-random. Fortunately I had a "new"
                          > pair of test sets with programmable patterns.)
                          >
                          >
                          >
                          > Ahh, the fun we had! It was fun to be an early adopter. :-)
                          >
                          >
                          >
                          > john
                          >
                          >
                          >
                          > _____________________________________
                          >
                          >
                          >
                          > John K Scoggin, Jr. W3JKS/AAT3BF/AAM3EDE/AAM3RE/AAA9SL
                          > US Army Military Auxiliary Radio System
                          > Delaware Gateway Station AAB3DE
                          > Special Consultant - Technology
                          >
                          > Emergency Operations Officer - DE and Region 3
                          > "Old RADEF Officers never die, they simply decay exponentially."
                          >
                          >
                          > Chief Engineer
                          > Mobile Communications Unit 37 (AAT3CAD/W3MCU)
                          >
                          > http://www.armymars.net/ArmyMARS/MCU<http://www.armymars.net/>
                          >
                          >
                          > ARRL Assistant Section Manager - Delaware
                          >
                          > Member, AMSAT and Radio Society of Great Britain
                          > Email: aat3bf@...
                          > Telephone: (302) 451-5000
                          >
                          >
                          >
                          > "There is a very fine line between a hobby and mental illness ..." - Dave
                          > Barry
                          >
                          >
                          >
                          > _____
                          >
                          > From: coldwarcomms@yahoogroups.com [mailto:coldwarcomms@yahoogroups.com] On
                          > Behalf Of David
                          > Sent: Friday, March 04, 2011 5:40 PM
                          > To: coldwarcomms@yahoogroups.com
                          > Subject: Re: [coldwarcomms] Re: Voltages
                          >
                          >
                          >
                          >
                          >
                          > On 3/4/11 5:01 PM, v6fiero@...<mailto:v6fiero%40yahoo.com> wrote:
                          >
                          >> Right before I retired as a HiCap tech 2 years ago we were using "double
                          >> doublers" on HDSL4 that extended the loop to about 15kFt on 22ga
                          >> copper.
                          > Interesting. But one of T1's strengths is you can string repeaters. It
                          > seems to me that the jitter limit is 150 miles; at 6kft per repeater,
                          > that's a lot of roadside cans.
                          >
                          >
                          >
                          >
                          >
                          > [Non-text portions of this message have been removed]
                          >
                          >
                          >
                          > ------------------------------------
                          >
                          > Yahoo! Groups Links
                          >
                          >
                          >
                        • Joe
                          Years ago, I remember Quasi , or Quasi Random Signal Source that we would put on all the spare T1 s at the toll office to keep them from oscillating and
                          Message 12 of 19 , Mar 5, 2011
                            Years ago, I remember "Quasi", or Quasi Random Signal Source that we
                            would put on all the spare T1's at the toll office to keep them from
                            oscillating and running wild.

                            Joe
                            > And that tendency to oscillate was a major problem because one singing
                            > repeater would wipe out adjacent T1's. Ooops....
                            >
                            > That was why there's the bit density mandate; to avoid oscillations. And
                            > that's why there were closed circuit loopback jacks and now SmartJacks that
                            > fall back to making traffic. I suspect current repeaters are far more
                            > stable; we've learned a lot in the intervening years.
                          • charlie Fargis
                            i remember that meter. It was on the L1 cable to Wash 1 and the paired cable to the Pentagon might even have been on the C&P local video cable that went to
                            Message 13 of 19 , Mar 6, 2011
                              i remember that meter. It was on the L1 cable to Wash 1 and the paired cable to the Pentagon
                              might even have been on the C&P local video cable that went to Hagerstown via microwave not AT&Ts

                              That "battery room" is actually where we had 2 diesel generators. The outline of the air in and exhaust are still visible.
                              With exception of the starting 24V batteries for the diesel in that room, at the 12 volt filament string in the radio area
                              all the batteries were in the basement.
                              To: coldwarcomms@yahoogroups.com
                              From: tad@...
                              Date: Wed, 2 Mar 2011 21:45:03 -0500
                              Subject: Re: [coldwarcomms] Re: Voltages




























                              Here's the Garden City meter setup:

                              http://tad.grosvenor.org/gallery/d/46340-2/IMG_1795.jpg



                              More at:

                              http://tad.grosvenor.org/gallery/v/Miscellaneous/GardenCity/



                              -Tad



                              ----- Original Message -----

                              From: "David" <wb8foz@...>

                              To: coldwarcomms@yahoogroups.com

                              Sent: Wednesday, March 2, 2011 5:19:18 PM

                              Subject: Re: [coldwarcomms] Re: Voltages



                              The positive voltage one end, negative on the other, trick has been around

                              since at least the early days of Trans-Atlantic cables. The repeaters are

                              in series DC-wise, so the first one works on {say} neg 1500 to neg 1400

                              volts. The second one was neg 1400 to neg 1300, etc. And the repeaters were

                              designed to fail open; when they did, the entire 3000 volts appeared across

                              it...and jumped a gap designed to melt shorted, restoring the cable with

                              one repeater-worth less gain.



                              (Obviously L-4 and T-1 repeaters are easier to access for repair than a

                              Trans-Atlantic cable one.)



                              I'm surprised L-3 used AC...



                              You used to see N2 cylinders on every third GTE pole until they got their

                              act together & started fixing the leaks. But that was POTS; I guess

                              L-carrier could use that as well. At Garden City, there was a conventional

                              gas meter on the dry air plant. It was to measure air used by the cable and

                              thus show there's a leak; as normally it would not move.



                              ------------------------------------



                              Yahoo! Groups Links


















                              [Non-text portions of this message have been removed]
                            • fdg135crm
                              There an abandoned outside cable pressurizer next to a manhole on the Finksburg/Dranesville route. It can be seen here: 39.240576,-77.234211 Google street
                              Message 14 of 19 , Mar 18, 2012
                                There an abandoned outside cable pressurizer next to a manhole on the Finksburg/Dranesville route. It can be seen here:

                                39.240576,-77.234211

                                Google street view shows it in slightly better condition than it is now. I have posted photos of it in the "L Cable Pressurizer" album.

                                Farrel Becker


                                --- In coldwarcomms@yahoogroups.com, charlie Fargis <lackey91@...> wrote:
                                >
                                >
                                >
                                > i remember that meter. It was on the L1 cable to Wash 1 and the paired cable to the Pentagon
                                > might even have been on the C&P local video cable that went to Hagerstown via microwave not AT&Ts
                                >
                                > That "battery room" is actually where we had 2 diesel generators. The outline of the air in and exhaust are still visible.
                                > With exception of the starting 24V batteries for the diesel in that room, at the 12 volt filament string in the radio area
                                > all the batteries were in the basement.
                                > To: coldwarcomms@yahoogroups.com
                                > From: tad@...
                                > Date: Wed, 2 Mar 2011 21:45:03 -0500
                                > Subject: Re: [coldwarcomms] Re: Voltages
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                > Here's the Garden City meter setup:
                                >
                                > http://tad.grosvenor.org/gallery/d/46340-2/IMG_1795.jpg
                                >
                                >
                                >
                                > More at:
                                >
                                > http://tad.grosvenor.org/gallery/v/Miscellaneous/GardenCity/
                                >
                                >
                                >
                                > -Tad
                                >
                                >
                                >
                                > ----- Original Message -----
                                >
                                > From: "David" <wb8foz@...>
                                >
                                > To: coldwarcomms@yahoogroups.com
                                >
                                > Sent: Wednesday, March 2, 2011 5:19:18 PM
                                >
                                > Subject: Re: [coldwarcomms] Re: Voltages
                                >
                                >
                                >
                                > The positive voltage one end, negative on the other, trick has been around
                                >
                                > since at least the early days of Trans-Atlantic cables. The repeaters are
                                >
                                > in series DC-wise, so the first one works on {say} neg 1500 to neg 1400
                                >
                                > volts. The second one was neg 1400 to neg 1300, etc. And the repeaters were
                                >
                                > designed to fail open; when they did, the entire 3000 volts appeared across
                                >
                                > it...and jumped a gap designed to melt shorted, restoring the cable with
                                >
                                > one repeater-worth less gain.
                                >
                                >
                                >
                                > (Obviously L-4 and T-1 repeaters are easier to access for repair than a
                                >
                                > Trans-Atlantic cable one.)
                                >
                                >
                                >
                                > I'm surprised L-3 used AC...
                                >
                                >
                                >
                                > You used to see N2 cylinders on every third GTE pole until they got their
                                >
                                > act together & started fixing the leaks. But that was POTS; I guess
                                >
                                > L-carrier could use that as well. At Garden City, there was a conventional
                                >
                                > gas meter on the dry air plant. It was to measure air used by the cable and
                                >
                                > thus show there's a leak; as normally it would not move.
                                >
                                >
                                >
                                > ------------------------------------
                                >
                                >
                                >
                                > Yahoo! Groups Links
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                >
                                > [Non-text portions of this message have been removed]
                                >
                              Your message has been successfully submitted and would be delivered to recipients shortly.