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kiwi cluster

edited March 2020 in BeagleBone AI
Since I've found an adequate cooling scheme, see: http://forum.kiwisdr.com/discussion/1939/alternate-cooling-method#latest

I have gone on to finalize my "kiwi cluster", 4ea BBAI based units combined with a common fan.



I went this route to reduce fan noise. The box on the back is a plenum for a single 90 X 90 mm AC fan. I used a best quality ball bearing fan.

Initially (see other thread) I had some ducting in the inlet side of the kiwi enclosure. I found today that was no longer needed, I stay below 44C, only 19 deg above room ambient.

Some of you may say "wow, that's a lot of dollars"... I can duplicate that for $1400 or $25/channel (there's the potential for 56 channels there). Better performance and less money that dongles!!
rz3dvp

Comments

  • Besides offering up to 56 simultaneous connections/channels this allows use of up to four antennas or filtered antenna paths. I have had 4 kiwis running for months, but never mechanically integrated like this. I use 2 of them for wspr, a different antenna on each and each running all 14 wspr bands. Rob's wsprdaemon combines and select sthe best signal and reports only that. A form of diversity. The other 2 are public access, one of each of my antennas.
  • Project is done mechanically, just needed to update the firmware in everything, configure and hook up antennas.
    Pix may be viewed at https://www.dropbox.com/sh/x7tt18loi84bpg3/AADLeN3iU6g7ZoPi520opbQpa?dl=0
    rz3dvp
  • Hi James, looks cool :smile:
    But be careful, heatsink on BB-AI fixed only on sticky thermal interface and I'm not sure how it will behave over time (about year) on high temp...
    You add lever arm to it. Maybe you know about FlexRadio 6400/6600 problem when similar heatsink installed vertical goes down under the influence of time and gravity.
    WA2ZKD
  • thanks for the heads up.....
  • http://www.jimlill.com:8073 and 8075 are the public access boxes and now both back online.
    8073 is on a Mag Loop and does 3 X 20 KHz channel mode
    8075 is on a vertical dipole and does 2+6 X 12 KHz channel mode
  • all systems running now... 2 unloaded kiwi/BBAI run 31 deg. and the 2 with 14 channels of continuous kiwiclient run 34 deg, in my cool basement
    Powernumpty
  • Yuri,
    Given the 33-34 deg temps I am seeing, I doubt that I will see an issue.
  • sytem running very well for 5+ days and my wspr spots have improved... seems like less RFI
  • 9 months later, still running without issue.

    johnk5mo
  • Nice. I reverted the BBAI as I couldn't easily and safely run cooling for it on the desk - and still use the desk :)

    Next place of living I might have another go at the upgrade. I still have the BBAI handy, and I have better standoffs to gain space for a fan+heatsink for when I get around to it.

  • edited December 2020

    I still think the mid-plate build is a good route for the AI. (if not in the original case)

    Yellow for Kiwi+AI, Green for AI. Purple just to hold the lower 6x40x50mm plate on (holes all wrong for best heat transfer without distorting the plate here)

    Red not used.

    60mm Kapton tape over the purple holes (with screws) and entire length of the plate, 0.8/1mm fibre washers under the KiwiCape.

    Only thing to watch for is the DC socket pins, might want to notch the plate there.

    I just haven't worked out an inexpensive way to put that sort of plate in the proper case getting the heat out but not having to modify the shell. Obviously depending on the amount of material in contact it still needs some air movement but many times less than small heatsinks.

    Plus I do believe there are noise gains to be had, don't have hard figures just gut feeling.

    Stu

    johnk5mo
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