fan in enclosure

And before anyone starts arguing that a fan is useless if it’s in an enclosed space, some thermodynamic hints:

• Heat moves due to temperature difference
• to move heat outside the enclosure, the walls of the enclosure need to be hotter than the outside
• with a fan, the differential between the pi / airspy and the air / walls of the enclosure will be reduced to around 10 to 20 C, without a fan the differential would probably be around 50 C or higher
• the enclosure has a relatively big surface compared to the pi / SDR, thus even 5 to 15 C differential will be sufficient to move the heat outside