Bill, that's quite an interesting mystery! Evidently, you're overloading the
power supply and it's shutting down, so I agree with Jerry's assessment.
However, from what I understand, the stepper motors are current driven, not
voltage driven. That means that even a short circuit in a pair of wires to
one of the stepper motor windings shouldn't overload the power supply. And
if you've checked all the resistances between pairs and they'r okay, and if
there's no resistance across pairs, then that pretty much rules out any
problem with the antenna. If there was an antenna problem, then the shutdown
would occur always when the same motor was energized. But that's not what
you're seeing.
Did you check to make sure there's no resistance between any of the control
cable pairs and the control cable shield?
Have you checked your AC line voltage? Your symptom could be explained if
the voltage is too low. Also, by any chance is your power supply plugged
into a GFI, UPS, or surge-protected circuit? One simple test would be to
measure your AC line voltage when you power up the controller and see if the
voltage sags. Also, if the power supply is plugged into an outlet strip,
then you could try changing it: it might be a faulty surge suprressor or
switch in the outlet switch with some resistance that's dropping your line
voltage.
Let us know what you learn, and good luck!
Jim W8ZR
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Bill Carnett
Sent: Sunday, June 10, 2007 9:42 AM
To: towertalk@contesting.com
Subject: [TowerTalk] SteppIR problem
Greetings to all Tower Talkers,
A very wise man and fellow TT (K7LXC) suggested I post
my challenge here to the group...maybe somebody will
have a new idea that I've not explored.
Last week we put up a new 4L SteppIR with a 40/30
dipole. The antenna is approximately 500 feet from
the shack. SteppIR control line is used, continously
without any accessories inserted, running through 3
inch conduit (not that that makes any difference).
Prior to lifting it in the air I found that a problem
existed. When attempts were made to change bands or
even frequency on the same band, the control box went
dead. Simultaneously, as the box died, the "on"
indicator light on the pwr supply went out. A second
later the pwr light came back on; the led "lights" on
the control box flashed once but the box remained off.
The box could be turned back on, but the same
sequence occurred if a band/freq change was attempted.
Immediately all of the wiring and continuity was
checked with the antenna...all ok. Spoke with Jerry
at SteppIR and we proceeded to change first control
box....before I realized the pwr supply was
faltering....no change.
The next step was to attempt to run each motor
individually and in groups. Each motor ran
individually without problem. Adding the 2nd and 3rd
motor caused no problems....the yagi functioned fine.
The addition of the 4th motor (didn't matter which
sequence), consistently killed the antenna. On
occassion it would all seem to work for a couple of
band changes but never more than 1 or 2 minutes - with
all 4 motors running. So, with up to 3 motors
running...all ok, with all 4, no go. However, this is
a 4 element yagi. After speaking again with Jerry, I
was reassured that the problem was simply a power
supply and all will work fine....thus the long
scheduled antenna raising event went forward as
scheduled. Needless-to-say, the replacement power
supply did not correct the problem.
Prior to erecting the yagi I extended the elements to
14150 so it can be used as a monobander...but that
will only bring temporary happiness. A power supply
(3rd) was "hand picked" by the SteppIR engineers,
sent, and tested this morning. Basically the same
problem. It did seem to work briefly then shut
down....exactly the same as before.
So, I'm looking for ideas that have been overlooked.
Yes, I should have listened to my gut, rather than the
"experts" and canceled the raising until all problems
were fixed, but that can't be undone. If this beast
must be lowered, I'm a bit reluctant to put it back up
after this experience. Yes, all antennas have
problems but it would be less $$ to replace it at the
time of lowering rather then taking down, bring the
crane back and forth, etc.
Sorry for the long-windedness of this but any and all
thoughts are appreciated!
73, Bill
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