Friday, January 27, 2017

Mesh Extender 2.0 Exterior and Interior drawings

Just a quick post with some images that have been generated so far during the design process, to give some idea of how the thing will fit together.  The exact dimensions and details are likely to have changed before we produce physical units, but give a clear idea on the concept.

First, from the front:

 Here  you can see the three antenna mounts: 2 for the UHF packet radio, and 1 for the WiFi. The other two bumps are screw bosses, so that you can make your own shade for hot locations to help keep the innards below 70C.  We have included this, because the thermal budget is just not quite there  for full-sun tropical locations, while sticking to only passive cooling, and with everything in an environmentally sealed case (which also traps heat).  Adding some shade fixes this problem.

We are not at this stage designing a shade, as we figure that they can be easily made by users from whatever they have laying around, for example, an old plastic bucket, waxed cardboard box, or even a drink can split open.

From behind:

The main thing to see here is the curved back to make it easier to strap to a tree or pole, and the ribbing to help provide at least a little air-flow between the unit and whatever it is attached to.

From below:
Here you can see the D-SUB 15 utility/IoT and D-SUB 25 power/radio connectors.  Also, below those you can see a couple of round markings which are drill guides in case you want to get ethernet out.  In their default state, they have gortex moisture seals to allow the unit to maintain equal pressure with the outside, without filling with condensation.

The inside of the top:

Here the main feature to see is the notch and paddle to help hold the PCB firmly in place, to minimise the effects of vibration, e.g., if a unit is mounted on a vehicle.

The PCB itself will sit inside, with fly-leads to the antennae, as shown in the remaining images.  Returning to the thermal properties, the main means for heat to exit from the unit is conductance through the antennae connectors.  Not ideal, but when you are making a sealed unit that you don't want to cost thousands of dollars per piece, your options can be rather limited.

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