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Re: [coldwarcomms] Re: TD-2 Microwave Equipment

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  • 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 1 of 5 , Jun 11, 2002
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      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:


      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!


      ----- 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
      > 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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