Thursday, July 30, 2015

Building a new antenna at N6QW ~ Part IV

Task Sequencing ~ Step by Step Task List

If you haven't guessed by now this blog is more to cause ME to think about how to install the new antenna and in doing so document and share the information. I tend to get a bit wordy, mostly out of fear that I will fail to include all of the detail needed to do the task. Please bear with me and in future posts I will try to be more economical in my word usage.
 

What goes where and what gets done first?

There are so many individual tasks that must be done and in somewhat drifting back to my days in aerospace manufacturing, we often found that items installed at one station had to be removed at a subsequent station to install the items at that downstream station. That was wasteful and caused a lot of rework and did I mention additional cost. There is also another consideration in that my current antenna mast has to be removed to make room for the new mast. Thus I will be "off air" for a period of time and the goal is to make that the shortest period of time possible.
 
This is more of a process that begins by identifying all of the tasks and to then order the tasks so that there is a logic to the install. Consideration must be given to tasks that can only occur in sequence versus tasks that can be done in parallel. It is difficult to raise a mast unless the foundation has been poured and the concrete cured is an example of sequencing. Again this first list is just items to be done and the second list will put those in a proper sequence (or sequencing).
 
  • Precisely set the area and size of the concrete foundation
  • Build a new house bracket assembly
  • Build the pulley assembly to raise the mast to a vertical position (mast is nested at this point)
  • Develop an MTO (Material Take Off ~listing of all tools, supplies and materials needed)
  • Build shop aids needed for the install
  • Calculate the length of the guys wires and guying anchor locations (two on the house and a third to a nearby fence)
  • Review all the clearances and alignment factors (When the mast is vertical and attached to the house bracket the clevis assembly must be in the center of the concrete base.)
  • Remove the existing antenna
  • Install the rotor on the mast. Include drilling a "pinning" bolt hole to lock the rotor to the mast.
  • Look at the wire run from the shack to the antenna/rotor. Evaluate existing junction box that was used for the satellite antenna as a junction box entry into the shack
  • The existing 20 Meter Extended Double Zepp will be reinstalled on the new mast which will be provide coverage on 40 and 80 Meters. Evaluate the attachment mechanism to the mast ~ most likely one of the guy rings.
  • Pour the foundation & allow three days to cure.
  • Perform a "fit check" of the mast to house bracket and foundation.
  • Without the beam or rotor installed raise the mast to assess the difficulty in raising just the mast and then evaluate the "Armstrong method" for raising the mast with the added weight of the beam, rotator and cables.
  • Erect a temporary random wire antenna for listening purpose while off air.
  • Pour the concrete with the mast in place to insure full alignment
  • Dig the foundation which at this point is a cube of about 1.4 feet cubed (120 Pounds of concrete).
I will be adding to this list and then finalize the sequencing/parallel activities. The final result is a critical path schedule (PERT) chart.


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