Sync on Green RGB video

[Douglas Taylor via cctech]

I have a couple of vaxes that output 'unique' video, Alpha 3000 300, 
Alpha 3000 400, Vax 4000 VLC, and Vax Station 3100 M76.

The Alpha and VLC each have a 3W3 type of connector and the 3100 has a 
15 pin DEC designed connector.

What does it take to connect these to inexpensive, modern VGA light 
weight monitors?

Doug