[TowerTalk] Homebrew Rotators

Bill Coleman aa4lr@arrl.net
Thu, 1 Nov 2001 14:53:58 -0500

On 11/1/01 6:03 AM, Zoltan.Pitman@libertel.nl at 
Zoltan.Pitman@libertel.nl wrote:

>I've been to this street and I never want to return... :)
>The pots are changing their resistance with humidity and especially
>temperature. In addition, RF can leak into your cable and superpose to the
>DC voltage resulting false readings. 
>73 de Zoli HA1AG

How about using a digital technique? I've seen wind direction indicators 
that drive a wheel made of transparent plastic. The wheel has several 
bands that are alternately dark and light. A bank of optical sensors 
detects if light passes through the bands or not. The bands are usually 
gray-coded binary.

With 6 bands, you can get a precision of a little more than 5 degrees. 
Typical wind-direction indicators are only show 1 of 8 (45 degrees) or 1 
of 16 (22.5 degrees)

An alternative, from a TowerTalk thread of long ago, is to buy a 
small-closed circuit TV camera and place it at the base of the tower, 
pointing up. (Preferably on the north side, so as to allow the tower to 
block out the sun during the day) Illuminate the antennas for checking 
the direction at night.

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901

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