Well, after another look in the beasties guts, converting it to run on
single phase 220 should be a simple task.  What I will do to mine is
remove the large three-phase cord (DEC #17-01806-01) and substitute a
home-brew cord #12-4 SO with a NEMA L16-20P plug.  

A few more details:

H405-E power distribution box, US 240 volt single phase (dryer or range
type).  There are three receptacles on the box, two on the back (where the
cord comes in), labeled FL3, & FL4.  These are switched, filtered power,
connected to the A phase (FL3) and B phase (FL4), fused immediately
adjacent to each receptacle. As I plan to feed the A phase and and B phase
with the two hot legs from the 240 volt power, nothing needs to be done
with these.  The third receptacle, J5, is located on the back side of the
box, internal to the chassis.  This is fed from the C phase.  As it is
internal to the computer, there is a good bet that something needs to be
plugged in there, so it will need to be moved to either the A phase or B
phase.  This is most easily accomplished by opening the box, loosening the
nut holding the brown wire going to the receptacle, and moving it to either
the red wire (A phase), or yellow wire (B phase).  I'm gonna put it on the
A phase, Just Because.  There are a number of other connections on the box,
these don't interest us at this time, with one exception: J4 on the back just
above where the cord enters.  This is protected/covered by a metal
shield-- DO NOT REMOVE THIS COVER!  Under this metal plate is a plug that has
UNSWITCHED (as in energised whenever the VAX is plugged in) three phase
power.  Anything that needs this plug will need to be examined, to see if
it will operate properly with 240 volt single phase, instead of the 208
volt three phase it's expecting.

There is one other safety modification that IMHO should be performed. 
Inside the `Power & Logic Box'-- the 300 volt DC power supply-- there are
three fuses just before the the power enters a full wave bridge rectifier
(the black thing on the B-I-G heatsink)  The fuse to the unused phase
should be removed. This will prevent power from backfeeding should the
rectifier fail in a shorted mode.  This is particularly advised for anyone
who will be leaving the original cord on (Brian ;) -- one pin of the plug
could become energised!

Now, the fine print:  I haven't exactly *done* this yet.  It is what I
will be doing, but I have other, more pressing, projects that are
consuming most of my time at the moment.

And please don't hurt yourself!

ja ne

Bob