[Elecraft] Stepper Motor

Fri Apr 1 09:30:36 EST 2005

Tnx for the feedback. Want to make it as seamless as possible. Don't want to
have to tune anything. I still have the option of switching in fixed value
caps to change the band segment to have a decent swr. If possible without a
ton of work, would like the ides of varying a calibrated pot in the shack to
have minimum swr at the part of the  band of interest.
73,
N2TK, Tony

-----Original Message-----
From: J F [mailto:phriendly1 at yahoo.com]
Sent: Thursday, March 31, 2005 1:48 PM
To: Robert Tellefsen; N2TK at arrl.net; vic at rakefet.com
Cc: 'Elecraft Discussion List'
Subject: RE: [Elecraft] Stepper Motor

Bob,

You may be able to attach a pot to the capacitor shaft
somehow and pass a voltage to a meter. You already
have a voltage at the motor, the rest is probably in
your junk box already. Tune up and note the readings
at each frequency of interest, then just drive back to
the appropriate setting.
It's cheap and dirty, but easy.
73,
Julius
n2wn

--- Robert Tellefsen <n6wg at comcast.net> wrote:

> Tony
> Here is one idea.
> I use a reversible geared down 12v dc motor to turn
> my tuning cap at the
> base of my
> vertical.  Typically I peak the vertical at either
> 1815 kHz or 1845 kHz.  I
> have to tune
> at low power and watch the swr meter for a minimum.
>
> For the coming winter I'm going to build a noise
> bridge that can be put in
> line
> and switched in and out at the same time I'm doing
> tuning.  The receiver
> will
> be the null detector and I won't have to transmit
> any signal at all.
>
> With this scheme I will be able to pick a frequency,
> peak the antenna, and
> never put
> out a signal ntil I'm ready.
>
> Good luck and 73
> Bob N6WG
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net]On Behalf
> Of N2TK, Tony
> Sent: Thursday, March 31, 2005 4:29 AM
> To: 'J F'; vic at rakefet.com
> Cc: 'Elecraft Discussion List'
> Subject: RE: [Elecraft] Stepper Motor
>
>
> Would be nice to have some kind of control to vary
> my vacuum variable cap on
> the shunt fed tower for 160M. A control like I have
> for my Vactrol's on the
> pennant antennas would be nice. I have the pot
> marked for 160, 80 and 75M.
> These settings correspond to the best F/B. Would
> like to use a similar type
> setting system marked from 1.8-2.0MHZ. The settings
> would correspond to the
> best swr for those frequencies. Use some kind of
> motor/selsyn drive on the
> cap?
> Would appreciate any feedback on ideas for this.
> N2TK, Tony
>
>
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net]On Behalf
> Of J F
> Sent: Wednesday, March 30, 2005 8:08 AM
> To: vic at rakefet.com
> Cc: Elecraft Discussion List
> Subject: [Elecraft] Stepper Motor
>
> 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.
>
> If you have something like the PIC-EL kit from AmQRP
> already, then the PIC option may be the easiest to
> work with first. From what I've read a lot of the
> robot folks seem to like the stamp approach.
>
> Look forward to reading some other input, and maybe
> some practical advice.
> cheers,
> Julius
> n2wn
>
>
> Message: 23
> Date: Tue, 29 Mar 2005 10:31:12 -0800
> From: Vic Rosenthal <vic at rakefet.com>
> Subject: [Elecraft] OT - stepper motor question
> To: Elecraft Reflector <elecraft at mailman.qth.net>
> Message-ID: <42499EF0.9000604 at rakefet.com>
> Content-Type: text/plain; charset=us-ascii;
> format=flowed
>
> I just know someone here can help me!  Please reply
> off-reflector.
>
> I recently had the opportunity to take apart a big
> old
> Ricoh copy machine.  I recovered all kinds of neat
> mechanical and electrical parts, inclucing
> bunches of solenoids, motors, etc.
>
> One of the coolest is a motor marked 55SPM-25D5A
> AX050032 30V 6.5 [ohms symbol]. Google gets nothing
> on
> either of these numbers.
>
> It has 6 wires coming out of it.  On the basis of
> this, and the 'coggy' feel when I turn the shaft, I
> think that it is a permanent-magnet unipolar stepper
> motor.
>
> I want to build a remotely tuned very QRO L-network
> antenna tuner (I already have a large rotary
> inductor
> and capacitor).  What I want to do is use this
> stepper
> to turn the capacitor to preset positions.  Once the
> capacitor is set, I will be able to drive the
> inductor
> with a simple geared motor and just tune for lowest
> SWR.
>
> Reading material on stepper motor control systems
> has
> my head spinning! Is
> there some kind of simple off-the-shelf controller
> that I can get that will do most of the work?  What
> I
> would REALLY like would be to just turn a local knob
> to adjust the capacitor (sort of like the way a
> selsyn
> acts), but there may be other approaches.
>
> --
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco
>
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