[eagle] Re: Still Even Another Revision

Chuck Green greencl at mindspring.com
Fri Oct 19 08:29:54 PDT 2007

Hi Dick,

Yes, 4.4mm will be more than enough and completely eliminate my concern.

I think Rick's suggestion is actually the more desirable situation. But 
practical considerations may very well preclude such an implementation. 
Juan's concerns are also valid. But we all know that the ideal situation 
often eludes us. Sometimes we must weigh the practical consideration of 
potential damage done by removing a module against the same potential if 
we don't remove it. And there are some things that can only be evaluated 
when the module is in the total satellite system. And there is the 
completely unknown (at this time) regarding the environment during a 
launch campaign. Keeping as many options as practical open to us is the 
best approach (IMHO).

Thanks for your work!


Dick Jansson-rr wrote:
> 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
> kd1k at amsat.org <mailto:kd1k at amsat.org>
> kd1k at arrl.net <mailto: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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