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Two Kiwi's in a hard drive box

For some reason I have been interested in putting Two KiwiSDR's in one box with simplified wiring.
So far I have two sdr's, a wireless router, two DC-DC supplies and a single Power over Ethernet cable coming in.
I have had an issue with one not starting the network in this configuration (this is the first time I've powered it up) but I've seen that before and I think I am causing the issue by having the SMA's grounded and connected to remote grounded feed lines, might also be the router sharing one DC-DC but that worked for a similar device before.
I intend to put power switches on the back and maybe some extra electrolytics in there, there's plenty of room ;-). The idea for the router was to have it wirelessly bridging to another but this three port thing just doesn't do it like the other Mikrotik hAP's I've tried, it seem to connect but is not routing and I decided to move on as I should be able to fix that later.
Of course my local QRM is running full bore right now so I'll have to defer noise tests or wait until I have it somewhere else. The POE should handle about 8-24V so I'll feel happier carting this somewhere and sticking a linear up the cable.

Comments

  • just add ferrite :-)
  • Be careful about heat dissipation in that configuration. At 1 to 1.5A @5V per Kiwi you're burning 10 to 15 Watts just for the Kiwis alone. Mount it vertically and hope for some convection or use a small fan.
  • There is a small fan underneath the router, 40mm, 12V running at 5V currently just felt it and I doubt the enclosure is above 30 Deg.
    I have found the SDR to be a bit better on current than the specs would suggest, the two Kiwi's on the linear PSU are showing (if I can trust the meters) 1.35A @ 5.2V, the router is max 3.5W.
    I had taken your previous comments about heat into consideration and will run the fan at 12V when we get the heatwave we are predicted..
    The supply on this is a 13.5V 1A wall wart and that is quite warm.
    Thanks for the reminder, wont't leave it on while at work just yet.
  • edited June 2019
    Jim, I wanted to start worst case then work out what to fix.
    currently these should be accessible at
    stucapon.plus.com:8075 -with outside antenna (waving in the wind, neighbour has his spark transmitter running)
    Second one :8076 -with 50 Ohm termination

    Something at 2.9MHz, and the general noise floor higher up the band but still less than local noise here.
    Will try ferrite and I did plan to put a mesh shield between the Kiwi's and the back part.
  • edited June 2019
    I changed the WSPR decode to point to this pair of SDR's and the second antenna, left it running for a couple of days, sat vertically on the long edge with the fan at the bottom it is about 13° C over ambient (currently about 21° in that room). I'm running the LZ1AQ active antenna (four 700c rims) from the DC input voltage from a Watson 10A Ham PSU (actually I've set it well under voltage spec for a "what would happen" test), decode spots seem the same or better than before. From the noise plots I've dropped the LZ1AQ sensitivity right down but WSPR seems to survive it, my other neighbour now runs something that puts 23db of noise across 30m and a little less on 60/80m, the WSPR ranking falls back when they are active. Overall I'm glad I did this as a test and will probably run my Kiwi from those little dc-dc unless I can find some other advantage to the expensive 5V linear supplies (on data modes anyway).
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