[jedcam67]

I have a shunt wound 1.5 hp dc motor and c6 speed control board from cnc4pc. Does anyone have any suggestions for a dc drive with reversing that would work with my motor and control board at a reasonable price, around $300?

[Al_The_Man]

You did not mention the voltage of the motor? If 90~120vdc and you require an analogue input controller then there are several vendors e.g. Baldor that sell a relatively cheap DC controller with field supply capability, You would have to set up the reversing by relay which each would typically be picked up by the M3/M4 command.
There are also usually several of these on ebay of re-labeled by various manuf.
If you get one from your Baldor rep. and are putting in an enclosure , they can be obtained without the case and Pot. for about 1/2 the price ~($100.00).
Al.

[NC Cams]

TI/Unitrode made an IC called the Uc3637. Their U-102 application note shows how to build a bidirectional speed control with the IC and an external current aplifier.

Essentailly ALL analog servo's use this particular method of speed and direction and currentcontrol to some extent or another.

[Al_The_Man]

You would need also to provide the shunt field circuit, which could be from 50v to max armature DC, the name plate should show it.
Al.