Hi Tomm
Do you know how many turns you need from lock to lock on the vacuum
variables? I might have something for you. This link may help you make a
choice for the size, http://www.cs.uiowa.edu/~jones/step/index.html
Vry 73, Paul
PAUL HEWITT
WD7S PRODUCTIONS
QRO HOMEBREW COMPONENTS
http://home.earthlink.net/~wd7s
----- Original Message -----
From: "KD7QAE" <KD7QAE@ARRL.NET>
To: <amps@contesting.com>
Sent: Wednesday, September 14, 2005 6:44 PM
Subject: [Amps] stepper motors
> I am (still) in the process of designing my dual gs35b amp and would
> like some advice on stepper motor selection. I have 2 Russian vacuum
> variable caps that I want to motorize and wonder if anyone on the list
> has found just teh right stepper to turn these babys. the tougher one
> is the 10 to 1200 pF unit. I can design the controller and drivers and
> will be linking them tothe vacuum relay coil tap selector on the PI
> inductor. The L section taps are selected by a manual switch which also
> sets the gross tuning position of the capacitors and the proper PI tap
> relay. I intend on using rotary digital pots to make the fine capacitor
> adjustments from the front panel and then having the option of storing
> the exact setting as read out from shaft encoders for quick setting in a
> particular rig / amp / antenna setup. Not autotune, but close.
>
> Tomm, KD7QAE
>
> PS, the plate choke is now done, removed 20T from one end and replaced
> w/ 5 wide space helical turns. I need some power FT caps for the AC
> wiring section to keep RF off the line cord as much as possible, anyone
> got some?
>
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>
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