K5LAD's  Assorted Ham Stuff

        K5LAD Rotator Correction

This program was born out of a need to correct a "slipped" mast on one of my towers.  It had slipped so badly that it wasn't even easy to correct the offset in my head so I decided to let my computer help me.  The first comment this might generate is, "why don't you just climb the tower with a wrench and fix the offset error."  There is an excellent answer to that but it could probably more easily be answered by directing you to another part of this web page to see a picture of the the author.  I am not a climber, I have never been a climber, gravity has such a severe grasp on me that no matter how far off my rotor turns out of alignment, I will not be able to climb that tower to make the correction.  Like the old song by the Beatles, I get by with a little help from my friends.  I must, however, await their timing and schedule and that means the rotor indicator and the actual direction of the beam must sometime wait until they're available.

For that reason, I developed this spreadsheet which allows the user to input the number or degrees the antenna is out of alignment (minus numbers for counter-clockwise and positive numbers for clockwise).   You can download the actual program by clicking on this:  Download the program.  You will need the Microsoft Excel program on a similar program which can read Excel files.  To make it work, it is assumed that you have turned your beam toward due North or due South and then looked at the rotator control head's indicator to see just how far off the correction factor might be.  With that number in hand, run the program and enter that number in the yellow highlighted box titled 'Rotor is off by __________ degrees'.  When you press <Enter>, the spreadsheet calculates the amount of correction needed to line your beam up with that rare DX station you're trying to work.  I then printed that page showing the corrections on the ink-jet printer and kept it handy.

Fortunately, my misalignment problem has now been corrected but I kept the program around, just in case I experienced slippage again.  I did not add any error trapping for the user who inputs a number higher that 360 (degrees).  It is assumed that if a person is smart enough to know they need this type of correction program that they are smart enough to at least be aware of the limitation of the compass rose. 

By the way, I guess this could also be used to calculate the offset if the user set their beam to point to magnetic North ("I knew that Boy Scout compass would come in handy some day.") and true North. 

Rotator Correction.jpg (86652 bytes)


It is probably obvious but the title on this spreadsheet mentions the TA-33jr because that is the antenna on my shorter tower which had the "slippage" problem.  I don't know if any of this information will be helpful to others but it has helped me. --- Jim - K5LAD

Created August 23, 2007   


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Last updated 11/06/2012 16:59:22 PM

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