[hpsdr] Some thoughts on plug-in board layout

[Philip Covington]

Hi Group,

Current Form Factor:

The current plan is a 100x100mm plug-in board format with a 96 pin
DIN41612 on the bottom side and  the board specific external
connectors on the top side.  It is loosely based on the Eurocard
format.  There is the option of increasing the length of the card
beyond 100mm, for example it could be 100x160, 100x200, etc...  The
external connector area does not increase when we go to these longer
boards.  There is a pretty good reason to no put connectors on the
perpendicular (left and right) sides of the board:  If we allow longer
boards than 100mm we will have to provide for board guides on those
sides.  I put some longer (100x160 and 100x220) eurocard format boards
that I had at work into the ATLAS.  With external connections those
boards can put a lot of stress on the ATLAS connectors.  If we allow
different board lengths it will make it very hard on those trying to
use an ATX case for an enclosure.

Proposed Form Factor (Alex):

I am not sure we would have to stick with one board size here.  I
looked at the ATX spec as well as the PCI card spec to determine the
maximum board dimensions we could use.  It appears that we could allow
100x120mm, 100x160mm, 100x185mm (Alex's proposal), and 100x220mm.
With 100x220mm we would be just inside the ATX motherboard footprint
so we could use ATX cases for all sizes from 120 to 220mm length.  The
longer boards in this configuration do not put as much stress on the
ATLAS.  The DIN41612 takes up a good amount of the fixed 100 mm
dimension.  There isn't this problem with PCI cards since they use
gold fingers.

Here is a PDF drawing of the proposed form factor:

<http://www.hamsdr.com/personaldirectory.aspx?id=261>

I added some the possibilities of the longer cards besides the
proposed 100x185mm.

I see pluses and minuses to each form factor.  I don't have any
problem changing it or redoing the OZY layout (since it isn't too far
along).  Lyle is further along on JANUS and he makes some good points
about signal flow in a previous post.  It matters less with the OZY
board since it is pretty much all digital signals (other than the USB)
and there are not the concerns of separating the analog and digital
sections like there is in the JANUS.

Take a look at the drawing about and please comment.  We need to get
this resolved soon so we proceed with the JANUS and OZY.

73 de Phil N8VB

P.S.  Please take a close look at the OZY schematic REVXA.5.  If it
looks good it will be the basis of the OZY alpha.  Very few made
comments but I posted it right before Dayton.

<http://www.philcovington.com/HPSDR/OZY/REVXA.5/>