Set LTSCALE to between 0.5 and 1.0 typically.
Sep PSLTSCALE to 1
Following pasted from Help document:
PSLTSCALE
Type: Integer
Saved in: Drawing
Initial value: 1
Controls paper space linetype scaling.
0 No special linetype scaling. Linetype dash lengths are based on the drawing units of the space (model or paper) in which the objects were created. Scaled by the global LTSCALE factor.
1 Viewport scaling governs linetype scaling. If TILEMODE is set to 0, dash lengths are based on paper space drawing units, even for objects in model space. In this mode, viewports can have varying magnifications, yet display linetypes identically. For a specific linetype, the dash lengths of a line in a viewport are the same as the dash lengths of a line in paper space. You can still control the dash lengths with LTSCALE.