[TowerTalk] US Tower HDX-589MDPL UP/DOWN switch failure

[john at kk9a.com]

I would definitely do something to ensure that you can turn off your tower
gear motor.  Changing to a 4 pole switch seems like an easy solution.  I
would also question why the switch contacts were damaged, are they
properly rated?

John KK9A


To:	"towertalk at contesting.com"
<towertalk at contesting.com>,	"lists at subich.com" <lists at subich.com>
Subject:	Re: [TowerTalk] TowerTalk Digest, Vol 151, Issue 6
From:	K2CB <k2cb at comcast.net>
Date:	Thu, 2 Jul 2015 11:21:29 -0400


Joe,

Good point on the two switches wired in series being an issue once the tower
reaches one of the limit points. In over thinking things, that fact
slipped my
mind.

While the use of a 4PDT switch to include the switching of the hot lead would
not be a bad idea safety wise, it still would not solve the issue if the
neutral contacts shorted during actual operation, as in my case. The overall
switch would still be in the on position while moving the tower.

At least the motor would not buzz when the switch is returned to the off
position if one set of contacts failed. But then again, that could be a bad
thing, because then you would not know if there it was a failure with one of
the other pole's contact set.

I guess the best solution is just to do periodic testing, and hope it does
not
fail in the wrong circumstance!

Eric
K2CB




>
>> Looking over the wiring diagram for the control box after the fact,
>> I am questioning why UST did not just simply wire the two limit
>> switches in series, then just use the UP/DOWN toggle switch to break
>> the connection between the series-wired limit switches and the motor.
>
> With the limit switches in series you would not be able to move the
> tower off either limit.
>
> It would be better to use a 4PDT center off to switch hot/neutral or
> a using separate switches - one to control direction the other to
> switch power.  The problem with the two switch version is the need
> to remember to stop motion before reversing direction.
>
> 73,
>
>   ... Joe, W4TV