[eagle] Re: Still Even Another Revision

Dick Jansson-rr rjansson at cfl.rr.com
Thu Oct 18 16:57:02 PDT 2007


Chuck:
 
Will 4.4mm suffice for your clearance in the center at the connector plate?
 
Rick's suggestions don't make very much sense as there is just not all that
much clearance space, inside of the spacecraft, to remove a 180mm PCB
assembly. when it is assembled with all of the (even simplified) cabling and
connectors. I am with Juan in this matter as these PCB assemblies need to be
handled with the greatest of care, considering all of the very small and
"tender" components and their junctions. Such removal must be done on a
properly equipped bench environment.
 
Dick Jansson, KD1K
 <mailto:kd1k at amsat.org> kd1k at amsat.org 
 <mailto:kd1k at arrl.net> kd1k at arrl.net 
 
-----Original Message-----
From: Chuck Green [mailto:greencl at mindspring.com] 
Sent: Thursday, 18 October, 2007 20.51
To: Dick Jansson-rr
Cc: Bob Davis; AMSAT Eagle
Subject: Re: [eagle] Still Even Another Revision
 
Hi Dick,
 
Given this design (no access without removing the module), I like it better
and better. I still have one *big* concern and that's the center mounting
screw for the front plate. The intrusion of the base plate into the PCB area
to accommodate this screw bothers me a lot. You point out that it does not
touch the PCB but it definitely precludes a connector at this location which
I see as a severe limitation on the connector area of the front plate. I
just measured a right angle flight Sub-D connector and its pins protrude
through the bottom of the PCB almost 1.5mm. I also measured a right angle
SMA connector and its pins protrude through the bottom of the PCB almost
2.5mm. I hope you can do something about this. I fear that the connector
plate area usefulness may have actually been degraded from the original
design.
 
Can you give us a view that shows the inside of the base plate directly
behind the front plate?
 
I'm looking forward to a dimensioned drawing. I suspect I'll have more
comments then.
 
Rick's suggestion of a base plate that includes the sides, back, and (I
would add) possibly the front gives us something like the modules for AO-51.
It probably would be stiffer, although I suspect the base you have just
designed is stiff enough (although you might be able to make the base plate
lighter if the sides/back/front were integral). I doubt there is any
advantage to being able to insert the PCB from the front due to clearances
within the satellite but you can evaluate that better than I. It would give
module builders the opportunity to secure heat producing parts such as
TO-220's directly to the walls (I did this quite a bit for P3D modules I
built). I know that these can be tricky to machine due to the flexing of the
walls if they get too thin. My $0.02 worth.
 
Chuck
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