From: Chris Zach
the DD11-B is a MUD backplane
No, it's SPC; other sources, e.g.
http://www.chdickman.com/pdp11/Notes/DD11.shtml
agree.
So if you have a DD11-B, you must have a BA11-D, with the 9-pin power
plugs.
The best thing to do is get a DD11-C or -D, and build an adapter cable to go
from a 9-pin male (shell; female pins) to a 15-pin
female (shell; male pins),
so you don't have to mess with the harness. Part
numbers here:
https://gunkies.org/wiki/DEC_power_distribution_connectors
Then you can plug in any memory you've got the right voltages for; the MS11-E
takes + and -15V (in addition to +5V, of course).
Noel