[hpsdr] Some thoughts on plug-in board layout

[pvharman at arach.net.au]

All,

A couple of comments on the new board design. I assume that the location of 
the DIN connector will be fixed such that any connectors on the edge of the 
board will always line up with the inside edge of the  enclosure i.e. any 
increase in card size will be on the opposite edge to where the  connectors 
are fitted.

Re the Janus connectors.  The prototype Janus board is showing a sensitivity 
in the uV region. The reason for keeping the outputs  (Left/Right audio and 
I/Q) well away from either the 3.5mm jack or  5 pin header is to try and keep 
as much separation as possible between these outputs and inputs.  We did 
debate a Delta 44 style break-out box some time ago, as well as the use of 
3.5mm jacks, and the current design reflects what was decided. 

My only concern with moving to the  new board layout is that we can keep all 
the digital signals out of the A/D front end.  At the moment at 192k  
bandscope width I can see the 48k clock feeding the TLV320 at about -120dBm. 
That may get better once we move to a PCB rather than dead-bug construction
. 
Time will tell. 

Phil
.VK6APH 




Quoting Philip Covington <p.covington at gmail.com>:

> ***** High Performance Software Defined Radio Discussion List *****
> 
> P.S.
> 
> I assume that we are adopting this general board form factor now?  My
> drawing was mainly to illustrate what the proposal was - it was not
> meant to be a spec or anything!
> 
> 73 de Phil N8VB
> 
> On 5/25/06, Philip Covington <p.covington at gmail.com> wrote:
> > Hi Steve,
> >
> > Comments in line below:
> >
> > On 5/25/06, Steven Bible <srbible at earthlink.net> wrote:
> >
> > > Attached is a mechanical drawing I did to hopefully understand the
> dimensions of an individual card.  I placed 100mm, 120mm, 160mm, and 185mm
> dimensions.
> >
> > I don't think the 100x100mm card will be wide enough for ATX case
> > mounting.  I had proposed these sizes in addition to Alex's 100x185mm:
> >
> > 100x120mm
> > 100x160mm
> > 100x220mm
> >
> > > Will someone tell me what the base measurement system will be (metric or
> inches)?  I think it should be metric, however, the DIN 41612 has base
> dimensions appear in inches.
> >
> > I'd like an answer to the question also.  Unfortunately its a mix when
> > you start looking at VMX or Eurocard formats - even the ATX spec mixes
> > units it seems.  The board spacing is 0.800", even though the board
> > sizes are given in mm.
> >
> > > Phil, in your ATLUS PLUG-INS drawing, you show 12.6 mm from the bottom of
> the PCB to the end of the DIN 41612 plug.  I think this is actually 7.37 mm. 
> The 12.6 mm is the top of the DIN plug plastic to bottom, not how it is
> mounted to the PCB.
> >
> > I would guess that my dimension is wrong.  I was working quickly
> > because I has a million things to get done today! :-)
> >
> > > The DIN plug that I used what the one Lyle called out for JANUS (AMP P/N
> 650473-5).
> > >
> > > I don't really understand the "external connector area".  Is this PCB
> material?  Or is this just an placeholder?  What is the interface plane?
> >
> > Its just to indicate where the external connectors should be placed.
> > There is no set dimensions for this on the drawing yet.  Think of the
> > boards as like PCI cards with a DIN41612 connector instead of gold
> > fingers.  The external connector area is where the PCI mounting
> > bracket is, and if used with an ATX case, this is where the connectors
> > will protrude through the back of the ATX case.
> >
> > > So looking at the card from the component side, the DIN connector is on
> the bottom, connectors on the left.  So nothing should be in top or to the
> right?  What notes should be added to this drawing to aid the prospective
> card designer?  Hopefully this drawing can be used as a basis for anyone
> starting a card.  Everyone, please comment on the dimensions you think should
> be put on it.
> >
> > I think we might want to designate an internal connector area
> > (internal to the ATX case or enclosure).  This could be on the top of
> > the board or the side opposite the external connector area.
> >
> > > The other drawing I would like to do has common components that should be
> on all plug in boards (serial epprom, etc.).  I need help if someone could
> list what these items are.  I can look at JANUS and OZY for examples.
> > >
> > > - Steve N7HPR
> >
> > Take the drawing as a very preliminary suggestion and you will
> > understand the spirit in which it was created ;-)
> >
> > 73 de Phil N8VB
> >
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