[hpsdr] Pandora question

[John Ackermann N8UR]

David McQuate said the following on 03/04/2009 06:41 PM:
> ***** High Performance Software Defined Radio Discussion List *****
> 
> Several questions:
> (1) The cards that plug into Atlas have connectros that protrude--
> which will be out the back of Pandora--preventing one from
> inserting a card, at least with a straight down motion.
> 
> I suppose each card could be tilted, inserting the connectors
> through holes in the back, then rotated slightly to engage with
> the Atlas connector.  Is that how it would work?

There is a "hatch" in the top of the enclosure that is removable without 
taking the rest of the case apart.  With the hatch off, the cards can be 
installed or removed without obstruction.  The hatch will have a foam 
strip so that when it is fastened down it applies pressure to the cards 
to keep them in place.

> (2) I've seen pictures of homebrew cases which accomodated LCD
> displays on the front.  Is the proposed Pandora height of 5.3 inches
> sufficient?

I don't know; depends on the LCD size, I suppose.  We didn't design the 
case with an LCD in mind.

And I should clarify that we're not in the design phase right now; the 
design is finished but for some finishing touches like determining how 
many extra connector holes to include, and we plan to go to production 
shortly after the interest list closes.

This Pandora, perhaps unlike the original, was motivated by the desire 
to get something out there quickly now that Penny, Mercury, etc., have 
made the HPSDR into a complete radio that needs an enclosure to move 
from the workbench into the shack.  So, we wanted to address the basic 
requirements, but not build an ultimate enclosure.

> (3) I'd hope to attach all the LPU regulators to at least a minimal heat
> sink.  If the LPU were placed next to a side wall that would allow
> bolting the heat sink to the side wall.  (keep everything cool!)

I believe LPU comes with heat sinks, and the fan is positioned to blow 
across them.  Scotty or Phil may chime in with their own views, but I 
believe they think that there is more than adequate cooling for the LPU 
with this design.

> (4) It would seem to me that a fan blowing air parallel to (i.e. between)
> the Atlas cards would be most effective in cooling the chips (especially
> Mercury's ADC.  Maybe the place for a fan is above the cards--increasing
> the case's height by the thickness of a fan (say 15mm (0.6") for a 70mm 
> square
> fan.  Maybe use two to cover all six of Atlas' slots and run them slowly
> to minimize noise.

I need to let Scotty and Phil chime in about cooling; they have been 
involved in the design of the enclosure, and as far as I know feel that 
there is adequate cooling for Atlas and its boards.  Increasing the case 
height would cause a problem with the hatch mechanism, so that isn't 
feasible.

> (5) The currently proposed case size easily accomodates a BeagleBoard or
> Nvidia ION motherboard, but an Intel Atom 330 mini-ITX is 6.75 x 6.75".
> Maybe the case should be 6.75" high (inside)...   (Yup, I can see I'm
> headed for "everything-in-one-box".

We didn't design for any motherboard other than Atlas, and we were 
trying to keep the size down -- this wasn't intended to be the 
"everything-in-one-box" box. :-)

73,
John
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