This VPI Power Line Conditioner (PLC) is a speed controller for any small turntable with a synchronous AC motor, but I only know it works for the HW-19s and Scouts for sure. Call VPI to see if you have something else and want to know if it is appropriate or not.
This speed controller is a huge upgrade for the HW-19s and allows you to adjust for variations in your local line frequency, plus provides a stable frequency for the motor whatever the fluctuations in the line might be.
These regularly sell on audiogon for $250, and I'm asking $225 shipped in the loer 48 with no paypal fee.
If you have an HW-19 (any version) and don't have an SDS, this will give you a huge leap in performance over the stock table with no power conditioning.
Thanks for looking,
Jim
P.S. -- I'll be selling my HW-19 with beautiful walnut base, very good condition acrylic dust cover, but no arm, as soon as I can find an appropriate box and packing materials.