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Re: [coldwarcomms] Re: Dual towers, how common?

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  • David Lesher
    Waldorf MD. I seem to recall seeing multiple towers there. -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host
    Message 1 of 14 , Nov 6, 2001
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      Waldorf MD. I seem to recall seeing multiple towers there.


      --
      A host is a host from coast to coast.................wb8foz@...
      & no one will talk to a host that's close........[v].(301) 56-LINUX
      Unless the host (that isn't close).........................pob 1433
      is busy, hung or dead....................................20915-1433
    • David Lesher
      ... I m sure I ve seen steel superstructure added to the top of silos such that they got more err antennas. (Skirting the were they horns? issue.) I am
      Message 2 of 14 , Nov 6, 2001
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        Unnamed Administration sources reported that dsandow@... said:
        >
        >
        > The whole design of the silo never contemplated the horn
        > reflector, with its bottom-feed. So you would have to put up a new
        > steel tower if you needed to upgrade to a horn reflector (for
        > improved performance) or raise the antenna (for obstruction
        > avoidance). But there was not a "transfer" of the horn reflectors.

        I'm sure I've seen steel superstructure added to the top of silos
        such that they got more err antennas. (Skirting the "were they
        horns?" issue.) I am thinking of the one along the Ohio Turnpike
        east of Cleveland. I have the Lat/Long in my GPS still, I think.



        --
        A host is a host from coast to coast.................wb8foz@...
        & no one will talk to a host that's close........[v].(301) 56-LINUX
        Unless the host (that isn't close).........................pob 1433
        is busy, hung or dead....................................20915-1433
      • joecheck@snet.net
        Oakdale (Montville) Connecticut comes to mind. Joe
        Message 3 of 14 , Nov 6, 2001
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          Oakdale (Montville) Connecticut comes to mind.

          Joe


          At 07:23 AM 11/6/01 , you wrote:
          >Message: 3
          > Date: Tue, 06 Nov 2001 06:19:51 -0000
          > From: "Pj" <packy41@...>
          >Subject: Dual towers, how common?
          >
          >How common (or uncommon) were the use of dual towers on a site? I
          >personally only know of two towers, one in PA and one at Durham CT.
          >Any other large use of dual towers?
        • dsandow@garden.net
          ... There are 4 circumstances where 2 towers are required. 1. The first tower on the site was limited capacity. The very first route (Boston-Washington) used
          Message 4 of 14 , Nov 6, 2001
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            --- In coldwarcomms@y..., "Pj" <packy41@y...> wrote:
            > How common (or uncommon) were the use of dual towers on a site? I
            > personally only know of two towers, one in PA and one at Durham CT.
            > Any other large use of dual towers?

            There are 4 circumstances where 2 towers are required.

            1. The first tower on the site was limited capacity. The very first
            route (Boston-Washington) used concrete towers - for rigidity - to
            prevent the tower from twisting in the wind. These were called
            "silos". The antenna deck was designed for the older "delay lens"
            antennas (a squat pyramid laid on its side), and could not physically
            accommodate the later horn reflectors. Further, there was only one
            antenna deck, so any additional routes through the repeater site
            could not be handled on the existing tower. By the time a second
            route was needed, the technology was steel towers and horn
            reflectors. Example of a silo and a steel tower side-by-side was
            Martinsville, NJ. (The silo was demolished in the '80s).

            2. Excessive weight/twisting. Colesville NJ was a major NYC junction.
            It had 8 routes (16 horns.) Just too much weight for 1 tower. (The
            added horns also added to the wind load, which increased the "sail
            area" of the tower, and increased the problem of the tower twisting
            in the wind.) The second tower was built right beside the first to
            share the load.

            3. The first tower was built high enough to carry antennas for the
            first route through the station. A later route required a higher
            tower. It's easy to hang additional antennas BELOW the top of an
            existing tower, but not easy to hang them ABOVE the top. The
            alternatives were to build a monopole extension (probably not good
            for much more than 20-40 feet due to wind-twist), OR to build a
            second tower higher than the first (again, Colesville, NJ).

            4. The most insidious reason for 2 towers is the alternating
            frequency plan. The available bandwidth was divided into "A" and "B"
            frequencies. A given station would transmit on the "A" frequencies
            and receive the "B" frequencies. This prevented RF crosstalk between
            the transmitters and receivers at the same station. (see more below).

            Now if my station transmits on "A" and receives on "B", then all the
            surrounding stations must be "B" transmitters, and so on forever. If
            you count all the hops on all the routes between - say - NY and
            Chicago, you will find that the hop count for every possible route is
            either an odd or an even number, because NY had to be an "A" station
            for all its routes, and CHI had to be a "whatever" station for all
            its routes. All the adjacent stations on all routes had to conform to
            the alternating pattern - ocean-to-ocean.

            In the case of NYC (call it "A"), all the adjacent repeaters (Jackie
            Jones, Green Pond, Martinsville, Iselin, Highlands) had to be "B"
            sites.

            So what happens if the alternation "slips", and a new route is built
            that would directly connect 2 adjacent "A" stations. It can't be
            done. You either have to build an intermediate station (2 short hops)
            to keep the plan straight, OR you build a second tower somewhere.

            An example of this is Green Pond, NJ. The first route was E-W
            (NY-Colesville-Jennerstown and points west.) Green Pond was the first
            hop out of NYC ("A" freq transmitters), so it used "B" freq
            transmitters. Then, someone decided to build a bypass around NYC. It
            connected Martinsville - Green Pond - Jackie Jones, ALL "B" stations.
            Something had to give. In this case, a new "A" station was built at
            Green Pond. It was really a separate station more than 500 ft from
            the existing. It was named Green Pond #2. Fortunately, the "B"
            transmit antennas at Green Pond #1 were pointing east-west and the
            "B" receive antennas at Green Pond #2 were pointing N-S, and the new
            tower was sited so that the receive antennas did not point at the old
            tower, so they got away with it. (And saved the zoning hassle of
            finding a different mountaintop in suburban NJ.)

            Green Pond #2 was absolutely a separate station from Green Pond #1.
            The only thing they share is a driveway. Even the alarms went to two
            different places - because the two towers belonged to 2 separate
            routes. There was no capability to do resoration patching between
            the two buildings. Just 2 separate repeaters on two separate routes
            that happened to share the same tax bill.

            More on crosstalk/leakage. Even though the horn reflectors had a very
            sharp beamwidth, you could still pick up a usable signal about 1/4
            mile off the centerline at 30 miles. IF an "A" transmitter and an "A"
            receiver were pointed in exactly the same direction, you could still
            get crosstalk from nearby reflectors. A building a mile away just
            slightly off the centerline could bounce the signal back. A passing
            truck on a highway in front of the beam could do the same, etc. To
            say nothing of ordinary leakage inside the station, regardless of how
            well shielded the receiver front ends were. The alternating
            frequency plan was one way to handle the crosstalk/leakage problem.
            There was also cross-polarization of the antennas for further
            isolation. But that's a different thread.
          • Terry Feathers
            I will agree that AT&T alternated frequency plans an almost all microwave sites. The exception was a route that had no growth potential or an engineer made a
            Message 5 of 14 , Nov 6, 2001
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              I will agree that AT&T alternated frequency plans an almost all microwave
              sites. The exception was a route that had no growth potential or an
              engineer made a very big mistake. Not alternating the frequency plan caused
              a "BUCK" station and you were limited to only using 1/2 of the possible
              channels or less. It would be time for the engineer to find a new job
              within AT&T.

              Regards
              Terry Feathers
              ComSpec Corporation
              Phone: 336-370-1456
              Fax: 336-370-4116
              email: tfeathers@...

              -----Original Message-----
              From: dsandow@... [mailto:dsandow@...]
              Sent: Tuesday, November 06, 2001 9:06 AM
              To: coldwarcomms@yahoogroups.com
              Subject: [coldwarcomms] Re: Dual towers, how common?


              --- In coldwarcomms@y..., "Pj" <packy41@y...> wrote:
              > How common (or uncommon) were the use of dual towers on a site? I
              > personally only know of two towers, one in PA and one at Durham CT.
              > Any other large use of dual towers?

              There are 4 circumstances where 2 towers are required.

              1. The first tower on the site was limited capacity. The very first
              route (Boston-Washington) used concrete towers - for rigidity - to
              prevent the tower from twisting in the wind. These were called
              "silos". The antenna deck was designed for the older "delay lens"
              antennas (a squat pyramid laid on its side), and could not physically
              accommodate the later horn reflectors. Further, there was only one
              antenna deck, so any additional routes through the repeater site
              could not be handled on the existing tower. By the time a second
              route was needed, the technology was steel towers and horn
              reflectors. Example of a silo and a steel tower side-by-side was
              Martinsville, NJ. (The silo was demolished in the '80s).

              2. Excessive weight/twisting. Colesville NJ was a major NYC junction.
              It had 8 routes (16 horns.) Just too much weight for 1 tower. (The
              added horns also added to the wind load, which increased the "sail
              area" of the tower, and increased the problem of the tower twisting
              in the wind.) The second tower was built right beside the first to
              share the load.

              3. The first tower was built high enough to carry antennas for the
              first route through the station. A later route required a higher
              tower. It's easy to hang additional antennas BELOW the top of an
              existing tower, but not easy to hang them ABOVE the top. The
              alternatives were to build a monopole extension (probably not good
              for much more than 20-40 feet due to wind-twist), OR to build a
              second tower higher than the first (again, Colesville, NJ).

              4. The most insidious reason for 2 towers is the alternating
              frequency plan. The available bandwidth was divided into "A" and "B"
              frequencies. A given station would transmit on the "A" frequencies
              and receive the "B" frequencies. This prevented RF crosstalk between
              the transmitters and receivers at the same station. (see more below).

              Now if my station transmits on "A" and receives on "B", then all the
              surrounding stations must be "B" transmitters, and so on forever. If
              you count all the hops on all the routes between - say - NY and
              Chicago, you will find that the hop count for every possible route is
              either an odd or an even number, because NY had to be an "A" station
              for all its routes, and CHI had to be a "whatever" station for all
              its routes. All the adjacent stations on all routes had to conform to
              the alternating pattern - ocean-to-ocean.

              In the case of NYC (call it "A"), all the adjacent repeaters (Jackie
              Jones, Green Pond, Martinsville, Iselin, Highlands) had to be "B"
              sites.

              So what happens if the alternation "slips", and a new route is built
              that would directly connect 2 adjacent "A" stations. It can't be
              done. You either have to build an intermediate station (2 short hops)
              to keep the plan straight, OR you build a second tower somewhere.

              An example of this is Green Pond, NJ. The first route was E-W
              (NY-Colesville-Jennerstown and points west.) Green Pond was the first
              hop out of NYC ("A" freq transmitters), so it used "B" freq
              transmitters. Then, someone decided to build a bypass around NYC. It
              connected Martinsville - Green Pond - Jackie Jones, ALL "B" stations.
              Something had to give. In this case, a new "A" station was built at
              Green Pond. It was really a separate station more than 500 ft from
              the existing. It was named Green Pond #2. Fortunately, the "B"
              transmit antennas at Green Pond #1 were pointing east-west and the
              "B" receive antennas at Green Pond #2 were pointing N-S, and the new
              tower was sited so that the receive antennas did not point at the old
              tower, so they got away with it. (And saved the zoning hassle of
              finding a different mountaintop in suburban NJ.)

              Green Pond #2 was absolutely a separate station from Green Pond #1.
              The only thing they share is a driveway. Even the alarms went to two
              different places - because the two towers belonged to 2 separate
              routes. There was no capability to do resoration patching between
              the two buildings. Just 2 separate repeaters on two separate routes
              that happened to share the same tax bill.

              More on crosstalk/leakage. Even though the horn reflectors had a very
              sharp beamwidth, you could still pick up a usable signal about 1/4
              mile off the centerline at 30 miles. IF an "A" transmitter and an "A"
              receiver were pointed in exactly the same direction, you could still
              get crosstalk from nearby reflectors. A building a mile away just
              slightly off the centerline could bounce the signal back. A passing
              truck on a highway in front of the beam could do the same, etc. To
              say nothing of ordinary leakage inside the station, regardless of how
              well shielded the receiver front ends were. The alternating
              frequency plan was one way to handle the crosstalk/leakage problem.
              There was also cross-polarization of the antennas for further
              isolation. But that's a different thread.



              Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
            • albertjlafrance@cs.com
              Yes, and one of them is a style I don t see often: the legs are vertical, rather than inclined (possibly flared outward slightly at the bottom). I believe
              Message 6 of 14 , Nov 6, 2001
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                Yes, and one of them is a style I don't see often: the legs are vertical,
                rather than inclined (possibly flared outward slightly at the bottom). I
                believe this is an older design.

                Another two-tower site in the DC area is the big radio junction called Omps -
                it's named for a town in WV but actually located just south of the VA/WV line.

                Albert

                In a message dated 11/6/2001 8:53:17 AM Eastern Standard Time, wb8foz@...
                writes:

                > Waldorf MD. I seem to recall seeing multiple towers there.
                >
              • dsandow@garden.net
                ... a ... ice ... Paul Thanks for reminding me that the silos had their radio rooms in the top of the tower. That would be another reason for the solid
                Message 7 of 14 , Nov 6, 2001
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                  > Catawba, OH (West of Columbus) - This is a strange beast as this is
                  a
                  > concrete silo with a guyed lattice tower standing next to it. An
                  ice
                  > bridge was placed from the TOP of the silo to the lattice tower to
                  > bring the waveguides from the lattice tower to the silo. (Obviously
                  > this was because the radio equipement was at the top of the silo...)
                  > The site was a repeater site (only two paths) and there are no
                  > antennas left on the silo... So I think they transferred the horns
                  > from the silo to the tower for some strange reason.

                  Paul

                  Thanks for reminding me that the silos had their radio rooms in the
                  top of the tower. That would be another reason for the solid
                  construction - to provide a benign environment for the equipment, and
                  to allow an enclosed weather-proof (and OSHA-proof) stairway for the
                  craftsmen to get to it.

                  As I mentioned in my earlier post, the silos were built for the delay
                  lens antenna. Think of a squat pyramid laid on its side, with the feed
                  point only a few feet from the equipment bays. (Actually, I think the
                  radio room was one level below the antenna deck because the antenna
                  deck was open to the weather.)

                  For more on delay lens antennas, see
                  http://www.tpub.com/neets/book11/46b.htm

                  The whole design of the silo never contemplated the horn
                  reflector, with its bottom-feed. So you would have to put up a new
                  steel tower if you needed to upgrade to a horn reflector (for
                  improved performance) or raise the antenna (for obstruction
                  avoidance). But there was not a "transfer" of the horn reflectors.

                  The waveguide bridge - it blows my mind. I suppose it would be cheaper
                  than building a new ground-level radio building to go with the new
                  tower, but that never stopped ATT. Is it still there?
                • allanbourdius@hotmail.com
                  Not always! The Troy Hill silo (AT #88265) north of Pittsburgh has a pair of KS horns on it. You can see them clearly in AT s photos of the site. Allan
                  Message 8 of 14 , Nov 6, 2001
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                    Not always! The Troy Hill silo (AT #88265) north of Pittsburgh has a
                    pair of KS horns on it. You can see them clearly in AT's photos of
                    the site.

                    Allan

                    --- In coldwarcomms@y..., dsandow@g... wrote:
                    > The whole design of the silo never contemplated the horn
                    > reflector, with its bottom-feed. So you would have to put up a new
                    > steel tower if you needed to upgrade to a horn reflector (for
                    > improved performance) or raise the antenna (for obstruction
                    > avoidance). But there was not a "transfer" of the horn reflectors.
                  • Paul J Zawada
                    ... That s not necessarily so... I ve seen many concrete silos that had short lattice structures added to the top to acommodate horns. Springfield, OH, off of
                    Message 9 of 14 , Nov 6, 2001
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                      > The whole design of the silo never contemplated the horn
                      > reflector, with its bottom-feed. So you would have to put up a new
                      > steel tower if you needed to upgrade to a horn reflector (for
                      > improved performance) or raise the antenna (for obstruction
                      > avoidance). But there was not a "transfer" of the horn reflectors.

                      That's not necessarily so... I've seen many concrete silos that had
                      short lattice structures added to the top to acommodate horns.
                      Springfield, OH, off of I-70, immediately comes to mind as well as
                      numerous towers along the Ohio Turnpike and Indiana Toll Road. (As
                      someone else has already pointed out.) There must be some reason they
                      didn't take the same approach at Catawba. You are right though...
                      The Catawba Silo may have never seen horns since there is no remaining
                      lattice structure on the silo... The guyed tower may have been there
                      the day the horns arrived. Maybe it was an experiment to determine
                      which way of conversion was better...

                      > The waveguide bridge - it blows my mind. I suppose it would be
                      > cheaper than building a new ground-level radio building to go with
                      > the new tower, but that never stopped ATT. Is it still there?

                      I have been by there in over a year, but I believe it's still there...
                      I've been meaning to run over there to take some pictures; maybe I
                      can do that in a couple of weeks...

                      --zawada
                    • albertjlafrance@cs.com
                      Another example of a combined silo and lattice-tower station is Waggoners Gap, PA: http://radio.ee.psu.edu/td-th/Waggoners_Gap/Waggoner s_Gap.html Albert In a
                      Message 10 of 14 , Nov 6, 2001
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                        Another example of a combined silo and lattice-tower station is Waggoners
                        Gap, PA:

                        http://radio.ee.psu.edu/td-th/Waggoners_Gap/Waggoner's_Gap.html

                        Albert

                        In a message dated 11/6/2001 8:44:41 AM Eastern Standard Time,
                        paul_zawada@... writes:

                        <SNIP>
                        > Catawba, OH (West of Columbus) - This is a strange beast as this is a
                        > concrete silo with a guyed lattice tower standing next to it. An ice
                        > bridge was placed from the TOP of the silo to the lattice tower to
                        > bring the waveguides from the lattice tower to the silo. (Obviously
                        > this was because the radio equipement was at the top of the silo...)
                        <SNIP>
                      • Chris Ness
                        ... Villa Rica, GA . Although one of them has been stripped of horns this Summer. It appears to the major connecting point for the west side of GA as well as a
                        Message 11 of 14 , Nov 9, 2001
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                          On November 6, 2001 01:19 am, Pj wrote:
                          > How common (or uncommon) were the use of dual towers on a site? I
                          > personally only know of two towers, one in PA and one at Durham CT.
                          > Any other large use of dual towers?
                          >
                          Villa Rica, GA . Although one of them has been stripped of horns this Summer.
                          It appears to the major connecting point for the west side of GA as well as a
                          CO.
                          --
                          Chris Ness
                          mailto:mness215@... All jobs are equally easy to
                          http://vivid.nbank.net/~gloster the person not doing the work.
                          Holt's Law
                        • albertjlafrance@cs.com
                          Terry, Thanks - I d seen the term buck station somewhere, but didn t understand what it meant until now. Albert In a message dated 11/6/2001 9:28:53 AM
                          Message 12 of 14 , Nov 20, 2001
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                            Terry,

                            Thanks - I'd seen the term "buck station" somewhere, but didn't understand
                            what it meant until now.

                            Albert

                            In a message dated 11/6/2001 9:28:53 AM Eastern Standard Time,
                            tfeathers@... writes:

                            > I will agree that AT&T alternated frequency plans an almost all microwave
                            > sites. The exception was a route that had no growth potential or an
                            > engineer made a very big mistake. Not alternating the frequency plan
                            caused
                            > a "BUCK" station and you were limited to only using 1/2 of the possible
                            > channels or less. It would be time for the engineer to find a new job
                            > within AT&T.
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