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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of N2TK, Tony Sent: Thursday, March 31, 2005 4:29 AM To: 'J F'; [EMAIL PROTECTED] 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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of J F Sent: Wednesday, March 30, 2005 8:08 AM To: [EMAIL PROTECTED] 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 <[EMAIL PROTECTED]> Subject: [Elecraft] OT - stepper motor question To: Elecraft Reflector <elecraft@mailman.qth.net> Message-ID: <[EMAIL PROTECTED]> 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 _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
