Jim Brown wrote:
>
> I just installed a 3-el with the new SD100 controller and the 33V power
> supply, and it's working just fine with 400 ft of 12-#22. Based on
> conversations with SteppIR, the primary cause of problems with the
> original controller and long lines is the inability of that unit to drive
> the CAPACITANCE of a long line, and the voltage driving the motors is a
> series of pulses. The greatly improved line drivers in the new unit are
> able to drive a lot more capacitance. Not a surprise -- we've had to
> address that problem in the pro audio world too, where mics and mix desks
> are often connected with more than 100 yards of cable.
>
> So while you COULD remote the controller board, you are far less likely to
> need to do so.
>
> 73,
>
> Jim K9YC
At the risk of disagreeing with an unnamed person at the factory, I
am not convinced about the capacitance argument. I made up a
jig with a bunch of series resistors to simulate a long cable.
It had no capacitors. I found that my controller (the original
version) shut itself off if the resistance exceeded about 30
ohms. Also, the waveform on the output of the controller is only a few
hundred Hz. The capacitive reactance is much larger than the resistance
at these frequencies. Microphones have to go to 20 kHz and the impedance
is at least 600 ohms, not a few dozen, so that may not be a great analogy.
BTW, interested readers might want to join the SteppIR reflector on Yahoo
Groups. Nothing wrong with posting about SteppIR on TT, but that
reflector is obviously more focused and has a lot of traffic.
Rick N6RK
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