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Dual towers, how common?

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  • Pj
    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
    Message 1 of 14 , Nov 5, 2001
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      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?
    • 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 2 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 3 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 4 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?
          • Paul J Zawada
            ... I can think of three installations off the top of my head: Montclair, IN (West of Indianapolis) - This was a major microwave installation with at least six
            Message 5 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?

              I can think of three installations off the top of my head:

              Montclair, IN (West of Indianapolis) - This was a major microwave
              installation with at least six paths. I'm not sure if a lot of
              muxing took place here... The building is a single story, approx.
              100'x60'. Big enought to house a lot of radio equipment but not
              enough to hold a lot of muxes and cross connects (unless there is an
              undeground floor). AMT site number #87772.

              Grant Park, IL (South of Chicago) - This was a major microwave and
              L3/L4 site that supported 7-8 microwave paths and 3-4 cables. Two
              story building with at least one or two floors underground. This
              would have been one of the major terminals for the Chicago area,
              handling the routes from the east and the south. I believe AT&T is
              still using the property for storage as there is a lot of outside
              plant (fiber) material stored at the site. (At least there was last
              time I was there a couple years ago...) AMT site nos. 87675 & 50263
              (They actually split this location into two sites. I think one of
              the towers is for sale or has been sold...)

              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. Perhaps they
              needed the raise the antennas to fix a clearence problem. It would
              neat to be hear the story behind this one. This is probably not
              really what you were looking for in a "two tower" location, but I
              threw it in because it's so strange... AMT site no. 87928.

              I hope I got the details right... I'm typing this mainly from memory.

              --zawada
            • 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 6 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 7 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 8 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 9 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 10 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 11 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 12 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 13 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 14 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.
                              Your message has been successfully submitted and would be delivered to recipients shortly.