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Re: [TowerTalk] SteppIR problem

To: <>
Subject: Re: [TowerTalk] SteppIR problem
From: "W5LT" <>
Date: Sun, 10 Jun 2007 21:19:39 -0500
List-post: <>
I too have been following your exploits, both here and on the SteppIR
I still believe the issue is related to the power supply. As Mike M. pointed
out, the motor drive is via current sources, thus the length of cable is of
secondary consideration. Howwever, the symptoms you describe point to a
current limiting effect in the power supply its self. That is, the system
runs fine with less than 4 motors running, kick in all four and the symptoms
show up, and the symptoms suggest a drop in the supply voltage (lights
flicker, controller shuts down, etc.).
Can you get a power supply capable of delivering more current, perhaps two
12V regulated supplies hooked in series?
Also, you might try to actually measure the voltage and/or current being
delivered by the power supply under load. 
If the voltage remains fairly constant when all four motors are driven, then
it is not the problem.

Bob, W5LT

-----Original Message-----
From: Dick Green [] 
Sent: Sunday, June 10, 2007 5:05 PM
To: 'James C. Garland';
Subject: Re: [TowerTalk] SteppIR problem


I've been following your exploits on the SteppIR reflector, too.

Jim's suggestions are excellent, and I would do all of the tests he
recommends. They're easy to do. 

Do you have a copy of SteppIR's Yagi Troubleshooting Guide? If not, you can
download it from the SteppIR site. It has all the wiring checks,
resistances, etc. You should check the resistance across each pair, and you
should make sure there's no continuity with the shield. 

But I suspect there isn't a wiring problem. I think that would have shown up
when you did the individual and group motor tests. For example, if one of
the wires was shorted to ground, one of the individual motors would have
caused problems. But do those resistance checks anyway.

If Jim's tests don't reveal the problem, you could try connecting an ammeter
in series with the power supply output to see how much current is being
drawn by the SteppIR controller at idle and when running the antenna. The
supply has max output of 2A, so it shouldn't be close to that. The spike may
be too fast to see, so you might want to borrow a logging multimeter or a
storage scope.

If you can get AC out to your tower, and if you can interrupt the control
line, then you definitely should test with the controller at the tower. That
would eliminate the long control line.

If none of the above reveals the cause, then I'd discuss the problem with
SteppIR again. If they feel the cable length is causing too much current to
be drawn from the power supply, and it's safe to supply more current to the
controller, you could try a bench supply with variable voltage of at least
33VDC and current limited output up to, say, 3A or so. But I wouldn't do
anything like that without clearance from SteppIR.

If it's not a problem with the cable being too long or the input voltage to
the power supply, then it would have to be some sort of motor problem that's
marginal enough not to cause a big current draw by itself, but added to the
three other motors pushes the power supply over the edge. That's probably
the worst-case scenario (other than miswiring at the antenna), because
you'll have to take the antenna down to fix it.

Been there, done that! 

73, Dick WC1M

> -----Original Message-----
> From: James C. Garland []
> Sent: Sunday, June 10, 2007 5:13 PM
> To:
> Subject: Re: [TowerTalk] SteppIR problem
> 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:
> [] On Behalf Of Bill Carnett
> Sent: Sunday, June 10, 2007 9:42 AM
> To:
> 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
> 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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