Looking for two DEC H445 power bricks for PDP 11/40 project

Paul Anderson useddec at gmail.com
Tue Sep 18 03:32:08 CDT 2018

I'll check my system tomorrow if I can. If you are using a DEC MS11-LB or
LD or compatible, you will need a DD11CK  or DK backplane. If used in a
BA11-BF, you will Need DD11-CF or DF, which is the same as the CK/DK, but
with a longer wiring harness.

DEC made an "extension cable" to do this, but thew are not many around. Or
just replace it yourself.


On Tue, Sep 18, 2018 at 3:11 AM, P Gebhardt via cctalk <
cctalk at classiccmp.org> wrote:

> >    > From: Henk Gooijen
> >
> >   > As far as I know, the 11/40 uses only one H745.
> >
> >Depends on what kind of memory it has. If MF11-L, it has two H745's; if
> >MM11-U, it has an H745 and an H754.
> >
> >(The harness has two different connectors for the 5th 'brick', so it can
> >handle either kind. At least, that's the situation on the later machines
> >[serial numbers above 6000]; early production /40's only support the
> MF11-L,
> >and you have to use special add-on harnesses to support an MF11-U in them;
> >see DEC-11-H40SA-B-D, Chapter 6 for the details.)
> As I don't have core memory modules available, I thought of using MS11
> memory,
> which, according to my research, seems to be an option for 11/40 systems.
> The system manual states on page 6-7 that the base power configuration
> consists
> of two H745 regulators and that one may be swapped with a H754 in case
> MF11-U
> memory is used.
> Does that mean that a single H745 regulator might be sufficient for my
> needs?
> All the best,
> Pierre

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