[Elecraft] Re: Stepper Motor

[J F]

Vic,
there was an article in QST a few years back on an
automatic antenna tuner that used steppers. The
feedback control used a basic stamp as I recall. It
was adaptable, if you want to write/modify code.

You may want to think about the rotary inductor. A
school of thought has it that they are slow beasts to
turn. Switching inductance in and out seems to be
faster and easier to control. If you're primarily a CW
op, switching is probably the simplest route to go. On
the other hand, if you do say CW/SSB/MARS a rotary
inductor makes more sense.

Thanks for the update!
Julius
n2wn

--- Vic Rosenthal <vic at rakefet.com> wrote:

> J F wrote:
> 
> > Actually Vic, I think a few folks might be
> interested
> > in this topic on the reflector (for a while). I,
> too,
> > have a number of steppers and would like to use
> them
> > for remote tweaking of a phased array.
> > 
> > I do know there are several controller kits
> available
> > and easily found. The question seems to be, what
> kind
> > of stepper do you have and exactly how do you wish
> to
> > control it? The are two options that seem to be
> the
> > most flexible, using a "Basic Stamp" or a PIC. 
> 
> I've received a great deal of input from folks on
> the reflector.  What I have is 
> a unipolar motor, which turns out to have been
> manufactured by Panasonic.  I 
> also have since removed various other steppers from
> old disk drives.  I've 
> ordered a driver kit from
> <http://www.electronickits.com> for $23, and there
> is 
> one offered for $13 at
> <http://store.qkits.com/moreinfo.cfm/QK179>.
> 
> I think I am not going to try to control it with a
> microprocessor at first.  My 
> L-network tuner will have a rotary inductor and
> variable capacitor, and possibly 
> a relay to switch in a fixed capacitor.  I will
> first try to set it up so it can 
> be tuned remotely using switches, buttons, possibly
> an encoder, etc.  I will 
> also provide some kind of position feedback to help
> me find preset positions 
> quickly.  If I'm successful, then I will think about
> automatically finding 
> presets or even tuning to minimize SWR.
> 
> Controllers are available that interface directly to
> a PC.  One possible 
> application would be to completely control a remote
> K2 -- including the RF and 
> AF gain controls -- from a PC.
> 
> -- 
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco
> 
>