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
I had no problems with this - use a 10 turn pot. Apply -8.0 volts to one
end and +8 adjustable to the other. When the pot is about in the middle of
the range, adjust the +8 volts until the voltage at the wiper is zero. That
is 0 degrees. Turn one revolution clockwise. Use a voltage divider on the
wiper and adjust until the voltage is .36 volts and read with a digital
voltmeter. I have a triple rotor controller I built using this and it's
accurate from -35 F to 100 F. It may be because any change in the positive
side is balanced by a change in the negative side.
For RF I use ferrite and bypass caps.
Frank
W2FCA
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