Mike,
I would bet that the switching supply is shutting down because
of a highly capacitive load and very high current peaks.
The stepper motors operate on square wave drive. The controller
is feeding 8 pairs of wire all with capacitance and all in
parallel as far as the power supply is concerned.
A 500 foot control cable is certainly long enough to act as a
transmission line since we have an "RF" control signal. I do
not know what the pulse frequency so I can't guess what kind of
impedance transformation might be happening.
If it were me, I would replace the switching supply with a
simple analog/linear supply using a 24 volt transformer,
a 5 Amp bridge rectifier and 2000 uF of filter capacitance.
With no electronic shutdown/foldback one could confirm that
the problem is higher than expected peak currents causing
the switching supply to shut down.
73,
... Joe, W4TV
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of shack
> Sent: Sunday, June 10, 2007 11:12 PM
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] SteppIR cable
>
>
> I still think it is the length of the cable. Has anyone tried
> to measure
> current and voltage when under load e.g. when all four elements are
> being adjusted? I think there is a voltage drop, which is why the
> controller malfunctions.
>
> Wire has resistance and a lot of wire has more resistance which has to
> be overcome.
>
> Have the Steppir folk actually tried driving a four element with 500
> feet plus of wire?
>
> Mike
>
> -----Original Message-----
>
> Several mentions were made that it was related to the 500 feet of
> control
> cable, but SteppIR's engineers say the longer cable would
> actually help
> reduce the load, so cable length has been ruled out.
>
> I dont know how the longer cable would help.
> I would look at the size of the cable. SteppIR makes two size, one for
> short runs and one for long runs.
>
> GL K4WZ Ron
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