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of the Channel Master 9521A.
Oct 18, 2013 16:15
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2 units in 2 months dead dead dead :(
Time owned: 3 to 6 months
First unit (a gift from a friend) was in service for about 2 months then quit with antenna (4el 2 M yagi and small VTenn vivaldi) pointing due North.
I knew I should have taken it apart to see what was wrong, but instead I purchased a second unit thinking that it was a fluke failure.
3 days later the new unit failed in the same fashion – stuck due North.
I dissembled both units and found the same problem with both.
The unit doesn’t have an internal sensor that tells the controller where it is pointed; instead it guesses (Number of 60Hz cycles? Amount of time on?) at the position and displays it's guess on the degrees indicator.
Periodically, you must “re-sync”. The “re-sync” procedure runs the rotator to due North (and past if necessary). At some point near (or even past) it thinks due North is, a steel pin on the main drive gear hits a steel peg on a secondary drive gear and prevents further rotation, stalling the motor, with the now zeroed degrees display.
It’s fun to watch the pin fly past and miss the peg at everywhere but due North as this thing rotates around. The “North-ing” mechanism is actually pretty darn clever.
Unfortunately, it is also mechanically unsound. The end-mount bearings on the gears, or perhaps the shafts themselves, bend enough such that the gears start trying to tear themselves free from their mounts, and finally bind up solid.
A whack with a hammer will free them up, but of course they bind up again the next time or 2 that the unit “hits the peg” at due north.
Nice idea, nice controller and display, but a Big Fat Zero for the mechanism.
Product is in production.
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