Hi Tom,
I've commented on this before... don't recall whether in public or private
e-QSO but, ...
I've built amps with both stepper motors and gearhead motors. The gearhead
units are easier (less parts) to drive and adapt to autotuning should it be
desired. Though, I will confess to overcomplicating the stepper implementation
by employing sine drive for quiet operation.
73 & Good morning,
Marv WC6W
-- KD7QAE <KD7QAE@ARRL.NET> wrote:
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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