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TD-2 Microwave Equipment

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  • Brad Cobo
    Group, I am looking for the technical specifications of the Western Electric TD-2 microwave transceivers typically found in many AT&T sites. Of particular
    Message 1 of 5 , Jun 5, 2002
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      Group,

      I am looking for the technical specifications of the Western Electric TD-2
      microwave transceivers typically found in many AT&T sites. Of particular
      interest are the dimensions and weight of each rack assembly. Does anyone
      know where I can find this info? Has anyone had experience removing this
      type of equipment?

      I will be removing some of these units in the next week or so and am trying
      to get an idea of what will be involved.

      Thanks,

      Brad Cobo
      College Station, TX
    • Albert LaFrance
      Brad, I don t have any authoritative answers, but I recently received some Bell System Practices (tech manuals) on microfiche, which I ve just begun to look
      Message 2 of 5 , Jun 7, 2002
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        Brad,

        I don't have any authoritative answers, but I recently received some Bell
        System Practices (tech manuals) on microfiche, which I've just begun to look
        through, so there's a chance I'll come across the info you need. But I
        don't know if and when I'll find it. In the meantime, here are my very
        rough guesses and approximations based on the few TD-2 installations I've
        seen:

        Bay width (racks were called "bays" in the Bell System): 18-20 inches.

        " height: 7-8 feet

        " depth: 12-16 inches

        " weight: 150 - 300 pounds

        The TD-2 is an old system, developed in the 950s, and has been modified
        repeatedly over the years. The surviving radios seem to encompass an almost
        infinite variety of configurations, including bays which have suffered
        various degrees of cannibalization. Obviously, this will affect weight.

        I'm just speculating here, but you might find that the bays are top-heavy.
        The bottom portion of the TD-2 originally contained four chassis of
        electronics, but these have been removed in some of the units I've seen.
        And while many electronic racks of the era contained heavy power supplies in
        the bottom positions, in the TD-2 system the power came from outside the
        bay. And the top of the bay contains some heavy metal waveguide components.

        My guess is that the bays were originally moved on some form of hand truck
        which kept them in a vertical position, and allowed them to be slipped into
        their place in a row of equipment from the front.

        In disassembling a row of TD-2s, you'll probably find two waveguide runs
        (one for transmitting, one for receiving) extending horizontally through the
        tops of the bays. At each bay, channel-separation filters connect the bay
        into the common waveguide.

        May I ask where this microwave station is located, and where the equipment
        is going? I'm very interested in seeing the old Bell System technology
        preserved in museums and other places where it will be appreciated.

        Albert

        ----- Original Message -----
        From: "Brad Cobo" <bcobo@...>
        To: <coldwarcomms@yahoogroups.com>
        Sent: Thursday, June 06, 2002 12:23 AM
        Subject: [coldwarcomms] TD-2 Microwave Equipment


        > Group,
        >
        > I am looking for the technical specifications of the Western Electric TD-2
        > microwave transceivers typically found in many AT&T sites. Of particular
        > interest are the dimensions and weight of each rack assembly. Does anyone
        > know where I can find this info? Has anyone had experience removing this
        > type of equipment?
        >
        > I will be removing some of these units in the next week or so and am
        trying
        > to get an idea of what will be involved.
        >
        > Thanks,
        >
        > Brad Cobo
        > College Station, TX
      • ozob99
        ... some Bell ... begun to look ... But I ... very ... installations I ve ... inches. ... modified ... an almost ... suffered ... weight. ... top-heavy. ...
        Message 3 of 5 , Jun 8, 2002
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          --- In coldwarcomms@y..., "Albert LaFrance" <albertjlafrance@c...>
          wrote:
          > Brad,
          >
          > I don't have any authoritative answers, but I recently received
          some
          Bell
          > System Practices (tech manuals) on microfiche, which I've just
          begun
          to look
          > through, so there's a chance I'll come across the info you need.
          But I
          > don't know if and when I'll find it. In the meantime, here are my
          very
          > rough guesses and approximations based on the few TD-2
          installations
          I've
          > seen:
          >
          > Bay width (racks were called "bays" in the Bell System): 18-20
          inches.
          >
          > " height: 7-8 feet
          >
          > " depth: 12-16 inches
          >
          > " weight: 150 - 300 pounds
          >
          > The TD-2 is an old system, developed in the 950s, and has been
          modified
          > repeatedly over the years. The surviving radios seem to encompass
          an almost
          > infinite variety of configurations, including bays which have
          suffered
          > various degrees of cannibalization. Obviously, this will affect
          weight.
          >
          > I'm just speculating here, but you might find that the bays are
          top-heavy.
          > The bottom portion of the TD-2 originally contained four chassis of
          > electronics, but these have been removed in some of the units I've
          seen.
          > And while many electronic racks of the era contained heavy power
          supplies in
          > the bottom positions, in the TD-2 system the power came from
          outside
          the
          > bay. And the top of the bay contains some heavy metal waveguide
          components.
          >
          > My guess is that the bays were originally moved on some form of
          hand
          truck
          > which kept them in a vertical position, and allowed them to be
          slipped into
          > their place in a row of equipment from the front.
          >
          > In disassembling a row of TD-2s, you'll probably find two waveguide
          runs
          > (one for transmitting, one for receiving) extending horizontally
          through the
          > tops of the bays. At each bay, channel-separation filters connect
          the bay
          > into the common waveguide.
          >
          > May I ask where this microwave station is located, and where the
          equipment
          > is going? I'm very interested in seeing the old Bell System
          technology
          > preserved in museums and other places where it will be appreciated.
          >
          > Albert


          TD2 was in standard 19" relay racks(bays) and came from the factory
          semi- crated, brought in on dollies & hoisted upright; however some
          CO
          equipment was installed in empty bays on site.

          Equipment Detail(ED) drawings and WeCo marketing brochures showed
          the
          dimensions,specs,etc but would be hard to find today.

          ----- Original Message -----
          > From: "Brad Cobo" <bcobo@n...>
          > To: <coldwarcomms@y...>
          > Sent: Thursday, June 06, 2002 12:23 AM
          > Subject: [coldwarcomms] TD-2 Microwave Equipment
          >
          >
          > > Group,
          > >
          > > I am looking for the technical specifications of the Western
          Electric TD-2
          > > microwave transceivers typically found in many AT&T sites. Of
          particular
          > > interest are the dimensions and weight of each rack assembly.
          Does
          anyone
          > > know where I can find this info? Has anyone had experience
          removing this
          > > type of equipment?
          > >
          > > I will be removing some of these units in the next week or so and
          am
          > trying
          > > to get an idea of what will be involved.
          > >
          > > Thanks,
          > >
          > > Brad Cobo
          > > College Station, TX
        • Brad Cobo
          Albert, thanks for the information. You are correct about the bays being heavy. The waveguide portions at the top of the bay are the heaviest, and it was found
          Message 4 of 5 , Jun 11, 2002
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            Albert, thanks for the information. You are correct about the bays being
            heavy. The waveguide portions at the top of the bay are the heaviest, and
            it was found that they needed to be removed before the racks could be
            separated and carried out. The waveguide sections are all interconnected,
            but some provisions have been made so that they can be removed relatively
            easily. The racks were bolted to the floor with one anchor and attached to
            the overhead cable racks with one or two bolts. With the major waveguide
            portions of each bay removed, the bay weighed approximately 250lbs.

            During the trip, a total of 6 bays were removed. This took approximately 12
            hours to complete with two men working.

            I now have the equipment and will be "breaking down" each bay to see what
            components are still usable(for ham radio applications). I will be glad to
            send any member of this list pictures, dimensions, etc regarding the
            equipment. Please email directly for this information. I do not have a
            detailed working knowledge of the parts of this system as of yet, but hope
            to understand the components and interconnection arrangement very soon.

            While at the site, I also took pics of just about everything which I will
            be forwarding to you for inclusion on the website if you so desire.

            Thanks,
            Brad
          • Albert LaFrance
            Brad, I searched through my hardcopy Bell System Practices, and found one which gives an overview of the system. I ll scan and post it ASAP. In the meantime,
            Message 5 of 5 , Jun 11, 2002
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              Brad,

              I searched through my hardcopy Bell System Practices, and found one which
              gives an overview of the system. I'll scan and post it ASAP. In the
              meantime, this labeled photo of a TD-2 bay from a Long Lines training manual
              might be of interest, although it depicts a model that's likely older than
              the ones you have:

              http://longlines.addr.com/tech-equip/radio/TD2_Chan_Maint/016.html

              If you have a photo of your TD-2s, I or someone else on the list might be
              able to ID some of its components.

              The TD-2 was the workhorse of the Long Lines microwave network, with
              something like 35,000 units manufactured. The first models used only vacuum
              tubes, but many were upgraded over the years to be completely solid-state,
              with much higher output power (5W vs. 0.5W, I think). The TD-2 has many
              interesting parts, including the channel-separation filters at the top of
              the bays.

              As you can see, the radio incorporates a transmitter and receiver in one
              rack. There were two basic configurations: a main-station (terminal) model
              which had separate microwave generators for the transmitter and receiver,
              and an auxiliary-station (repeater) model which contained one microwave
              generator plus a frequency shifter which produced a carrier signal offset by
              40 MHz from the generator output. The latter configuration supported the
              TD-2 frequency plan, where transmit frequencies alternated at consecutive
              repeater stations.

              The TD-2 input and output was a 70 MHz FM intermediate-frequency signal,
              which in later models could carry up to 1800 analog
              frequency-division-multiplexed message (voice) channels, or a lesser number
              of voice channels and one TV channel.

              Note: I'm not an expert on this (or any) technology; corrections to any
              misinformation I may have posted are most welcome!

              Albert

              ----- Original Message -----
              From: "Brad Cobo" <bcobo@...>
              To: <coldwarcomms@yahoogroups.com>
              Sent: Tuesday, June 11, 2002 11:55 AM
              Subject: [coldwarcomms] Re: TD-2 Microwave Equipment


              > Albert, thanks for the information. You are correct about the bays being
              > heavy. The waveguide portions at the top of the bay are the heaviest, and
              > it was found that they needed to be removed before the racks could be
              > separated and carried out. The waveguide sections are all interconnected,
              > but some provisions have been made so that they can be removed relatively
              > easily. The racks were bolted to the floor with one anchor and attached to
              > the overhead cable racks with one or two bolts. With the major waveguide
              > portions of each bay removed, the bay weighed approximately 250lbs.
              >
              > During the trip, a total of 6 bays were removed. This took approximately
              12
              > hours to complete with two men working.
              >
              > I now have the equipment and will be "breaking down" each bay to see what
              > components are still usable(for ham radio applications). I will be glad to
              > send any member of this list pictures, dimensions, etc regarding the
              > equipment. Please email directly for this information. I do not have a
              > detailed working knowledge of the parts of this system as of yet, but hope
              > to understand the components and interconnection arrangement very soon.
              >
              > While at the site, I also took pics of just about everything which I will
              > be forwarding to you for inclusion on the website if you so desire.
              >
              > Thanks,
              > Brad
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