Shielded rack mount case for 6-8 KiwiSDRs
Has anyone made a home brew rack mount case to hold 6-8 or more KiwiSDRs ? Local interference is a major consideration when setting up a multi-KiwiSDR station and something like a Faraday Cage for each KiwiSDR is probably worth the effort. I have seen comments saying that the KiwiSDR aluminium box is a useful addition to reduce the local interference but my experience has been that the internal temperature increase in the box is unacceptable. I figure that a home brew rack case with "blade" type slide in sub-assemblies with individual Faraday Cages might be a better fix. Add to that a good supply of clean and cool air from the back of the rack mount case and it might be a real winner. A large 6 inch fan or multiple 3.5 inch fans can certainly move some air to help prevent the KiwiSDR and RPi PCBs from cooking on a hot day. We get lots of hot days here in Australia so good cooling is essential.
Any ideas or suggestions ? Thanks, Jamie VK2YCJ
CMI on the cables is a bigger issue than shielding in my experience. I have a cluster of 4 and KD2OM has 3.
CMI as in Common Mode Interference ? Okay, cables as in antenna, GPS, power supply and Ethernet ? Some Common Mode Choke designs created by K9YC using Fair-Rite Mix-31 cores might do a good job on those cables. I saw or read somewhere that Rob AI6VN was also looking into using GPS adjustment or stabilisation on the KiwiSDR oscillator to reduce frequency or phase jitter to help things along. I cannot remember where I saw that and I'm not certain that I have the story right on that. DX-Engineering has Ethernet ISO-PLUS Ethernet RF Filters (DXE-ISO-PLUS-2) available. Do you know if anyone has used USB WiFi dongles with success ?
If I was going to rack them up I'd probably use a plate to put a heatsink on the BBG, not that it needs much but it could be passive if built up that way. I did have a couple of BBG+Kiwi side by side in a metal hard drive enclosure and if the BBG was close to a metal plate I didn't need much fan, in fact I would not have one running except in rare UK heat waves. Image as it is easier to show than describe, the plates could be laser/water cut 1.5mm (not 2&1mm like here) spacers probably something like 6x13mm.
--edit-- I seem to remember the gap from bottom of Beaglebone to top of green antenna connector needs to be over 29mm, so 2x14mm with a 1.5mm plates would work but is non standard stock.