[TowerTalk] Ham IV rotor

[Tom Anderson]

Fellow Tower Talkians:

Thanks to all of you for the replies about my rotor problem.  It appears 
  that the problem is in the pot and I took it down today and am 
shipping it off to Norm's Rotor Service since I think a couple other 
things need checking.  I checked it once I got it down and it still had 
the wild meter swings even though the rotor itself turned fine.  Norm's 
said they have a new type pot that may eliminate the problem with the 
pot and his website says the following:

"12. Why does the direction indicator meter stop and start and give an
  erratic indication when my rotor turns?

  Contrary to popular belief, this problem is caused by a dissimilar
  metals problem in the rotor.  The rotor pot, which is the sensor for he
  position indicator, is made of tungsten wire with a copper wiper.  The
  pot shaft is turned by an aluminum housing.  This combination causes
  corrosion to accumulate on the pot, which then causes erratic movement
  of the meter."


Most of you suggested the pot as the cause and were right on
target.

Once again thanks to all of you for the help.

Tom Anderson wrote:
> 
> 
> Fellow Tower Talkians:
> 
> I've got a Ham IV (1987 vintage that has been overhauled three years ago 
> by Norm's Rotor Service).  But I still seem to have problems with it 
> such as wild meter swings, etc.
> 
> A few months ago I completely replaced the rotor cable with one that has
> 2 16 ga and six 18 gage wires in about a 75 foot total run.   Now it 
> seems to be on the fritz again.  Can't get any readings from the rotor 
> itself at the control box, per using the Telrex/Hygain manual.  SHould I 
> step up to a higher gauge wire, which would probably be overkill at such 
> as short distance of 75 ft. total.  The cable is attached to my Tri-Ex 
> 50 foot crankup by 3 standoffs bought with the tower.
> 
> The connectors on both ends are 8 plug trailer disconnects from Wireman 
> and are each wrapped first in heat shrink tubing, then Scotchcoted, then 
> wrapped in Scotch 33 tape and Scotchcoated again, and finally in a piece 
> of sticky butyl rubber made for weatherproofing large outdoor 
> connectors, and this is Scotchcoated again.  I don't think moisture is 
> the problem, just can't seem to isolate what is the problem though.
> 
> The system is wired so I can take the rotor control box direct to the 
> rotor and plug it into the rotor pigtail I ran from the 8 screw terminal 
> board to the trailer disconnect.
> 
> May have to pull the whole thing down and start over as far as cabling 
> is concerned, However, I will crank the tower down and take the rotor 
> box to the rotor and connect them directly to see if the problem is 
> somewhere in the 75 foot run of rotor cable.
> 
> Any suggestions gladly accepted.
> 
> 
> Tom, WW5L
> 
> 
> 
> 
> 
> 
> _______________________________________________
> 
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> Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
> any questions and ask for Sherman, W2FLA.
> 
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