[TowerTalk] TIC Potentiometer

john at kk9a.com john at kk9a.com
Fri Apr 4 08:18:40 EDT 2014

Apparently there are at least two common TIC ring problems, gear slippage
and indicator failure.

Gear slippage should not occur if the guide roller holds the ring gear
against the motor. The further the motor is from the roller the more
likely it will disengage. I have not seen this problem with my older style

The sensor is a potentiometer and unfortunately it is mounted in a box
that is not very waterproof. A pot with an IP67 water resistance rating
would sure be nice but I have yet to find one.  Most pots that I have
found seem to have no shaft seal and with them facing upward eventual
failure is likely. Switching to a different positioning indicator such as
a reed switch is also a possibility, but this is a major design change.

John KK9A

To:	 "towertalk at contesting.com" <towertalk at contesting.com>
Subject:	 Re: [TowerTalk] TIC Potentiometer
From:	 "Zivney, Terry" <00tlzivney at bsu.edu>
Date:	 Fri, 4 Apr 2014 02:17:42 +0000
List-post:	 <towertalk at contesting.com">mailto:towertalk at contesting.com>
I seem to recall K1TTT said the earliest rings used a pulse counter
instead of
the pot.  The implication being that the pulse counter approach had problems
and was upgraded to the pot.

A basic problem with putting the whirling magnet on the motor shaft is
that it
only counts how many times the motor shaft turns.   But, many of he rings
appear to skip or slip or miss a beat (whatever you want to call it). So, the
ring location is computed by counting the number  of rotations of the motor,
not the rotations of the ring.

In my case, the pot reliably follows the motor and the spur gear that is
supposed to drive the ring.  The problem with inaccurate readout is not
caused in these cases by the pot but rather by the spur gear and ring
gear losing contact from time to time.

It seems that is also the case with the ring in the recently posted YouTube
video of a  TIC ring problem.

A pulse counting technique that is counts motor revolutions is not inherently
superior to a precision potentiometer geared to that same motor.  The
pot is a ten-turn pot which has lots of resolution potential (sic).

Terry N4TZ

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