Bob:
Owing to the "popularity" of these discussion, I have done further revisions of the E05 20 Module. It is now officially termed a "140x180" module as the PCB has grown to that size. The size increase has allowed an increase in PCB working area to a clear 126x173.6mm, 6.35mm deep, save for three protrusions - two support posts and the third at the front to accommodate the third connector plate screw (this later post is not in contact with the PCB as explained earlier). The three attached PDF files show the module with its cover attached, cover removed and PCB and cover removed.
I shall shortly be able to issue a drawing of this revised PCB.
The cover has further been simplified as the rear mounting flange has been removed and replaced by side-inserted screws, as is for the cover's sides.
Chuck has properly noted that such a mounting of the PCB will enhance the thermal characteristics of the PCB. I plan to combine an earlier PCB thermal analysis and this new PCB configuration and expect to be able to identify the power handling capability of this PCB without the use of any added heat sinks. The enhancement should certainly be available along three sides of the PCB. That data should be available for the Symposium.
Dick Jansson, KD1K mailto:[email protected] [email protected] mailto:[email protected] [email protected]
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
Dick Jansson-rr wrote:
Bob:
Owing to the “popularity” of these discussion, I have done further revisions of the E05 20 Module. It is now officially termed a “140x180” module as the PCB has grown to that size. The size increase has allowed an increase in PCB working area to a clear 126x173.6mm, 6.35mm deep, save for three protrusions – two support posts and the third at the front to accommodate the third connector plate screw (this later post is not in contact with the PCB as explained earlier). The three attached PDF files show the module with its cover attached, cover removed and PCB and cover removed.
I shall shortly be able to issue a drawing of this revised PCB.
The cover has further been simplified as the rear mounting flange has been removed and replaced by side-inserted screws, as is for the cover’s sides.
Chuck has properly noted that such a mounting of the PCB will enhance the thermal characteristics of the PCB. I plan to combine an earlier PCB thermal analysis and this new PCB configuration and expect to be able to identify the power handling capability of this PCB without the use of any added heat sinks. The enhancement should certainly be available along three sides of the PCB. That data should be available for the Symposium.
Dick Jansson, KD1K
[email protected] mailto:[email protected]
[email protected] mailto:[email protected]
Via the Eagle mailing list courtesy of AMSAT-NA [email protected] http://amsat.org/mailman/listinfo/eagle
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:[email protected] [email protected] mailto:[email protected] [email protected]
-----Original Message----- From: Chuck Green [mailto:[email protected]] 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
All: At some point, after the free-form discussion is converging to hard comments, I'd like to seem them posted on EaglePedia, for formal, public response. Thanks to Dave Hartzell, the comments page is: http://www.amsat.org/amsat-new/eagle/EaglePedia/index.php/Module_Requirement...
Thanks & 73, Jim [email protected]
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
[email protected] mailto:[email protected]
[email protected] mailto:[email protected]
-----Original Message----- From: Chuck Green [mailto:[email protected]] 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
Via the Eagle mailing list courtesy of AMSAT-NA [email protected] http://amsat.org/mailman/listinfo/eagle
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!
Chuck
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
[email protected] mailto:[email protected]
[email protected] mailto:[email protected]
-----Original Message----- From: Chuck Green [mailto:[email protected]] 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
It may be possible to put the hottest components of the 70 cm receiver near the edges of the board and provide 2 or more layers of 1-2 oz. copper between the exposed pad on the bottom of the IC and the edge. The PCB suppliers usually recommend a 20 mil clearance between the ground plane and the edge of the board and the edge of the board needs to be 10 mils from the edge of the enclosure. There needs to be enough remaining overlap to to acheive a low thermal resistance.
73,
John KD6OZH ----- Original Message ----- From: Dick Jansson-rr To: Bob Davis Cc: AMSAT Eagle Sent: Thursday, October 18, 2007 19:56 UTC Subject: [eagle] Still Even Another Revision
Bob:
Owing to the "popularity" of these discussion, I have done further revisions of the E05 20 Module. It is now officially termed a "140x180" module as the PCB has grown to that size. The size increase has allowed an increase in PCB working area to a clear 126x173.6mm, 6.35mm deep, save for three protrusions - two support posts and the third at the front to accommodate the third connector plate screw (this later post is not in contact with the PCB as explained earlier). The three attached PDF files show the module with its cover attached, cover removed and PCB and cover removed.
I shall shortly be able to issue a drawing of this revised PCB.
The cover has further been simplified as the rear mounting flange has been removed and replaced by side-inserted screws, as is for the cover's sides.
Chuck has properly noted that such a mounting of the PCB will enhance the thermal characteristics of the PCB. I plan to combine an earlier PCB thermal analysis and this new PCB configuration and expect to be able to identify the power handling capability of this PCB without the use of any added heat sinks. The enhancement should certainly be available along three sides of the PCB. That data should be available for the Symposium.
Dick Jansson, KD1K
------------------------------------------------------------------------------
_______________________________________________ Via the Eagle mailing list courtesy of AMSAT-NA [email protected] http://amsat.org/mailman/listinfo/eagle
participants (4)
-
Chuck Green -
Dick Jansson-rr -
Jim Sanford -
John B. Stephensen