At least I am satisfied : a power supply story


- First of all, I have "delocalised" the Kiwi SDR in my parent's house to be far from my computers, Raspberries, other SDR radios... But it was not very good : too much noisy
- Then I have removed the switching 5V 2A power supply for the Kiwi and replaced it with an old linear regulator industrial 5V Lambda PS. It was better.
- Then I have removed all the PLC network of the house, moved the WiFi router on the first floor (the Kiwi is in the attic). It was better. The PLC are VERY noisy in SW.
- Then I have replaced the 12V power supply of the antenna with an old CB 12V power supply.
- Finally today, I have replaced the little PS given with the Ethernet-Wifi interface by a linear one bought on ebay.

Now I am very very satisfied, no more "bzzzz, crrrrr.....".  Try for example Northwood fax on 8038.1.

Take care of your supplies, this is far more important that you could imagine.

73's de J-Luc F1JEK


  • jksjks
    edited July 2017
    Excellent J-Luc. Yes, it takes real work sometimes to achieve decent shortwave reception in the modern world. We have a few more suggestions on the website: Noise reduction advice It is very worthwhile experimenting with grounding configurations. And we found this video about broadband mains noise very surprising: EMC & Shack Noise: Filtering the mains supply

  • Hi,

    The grounding in HF is a very touchy subject. As soon as it's to evacuate to the earth a leakage current like for a washing machine, it's easy (safety ground). But in HF the goal is more to have a "heavy" reference, and to send to the ground HF currents like shield currents, which are faint but high frequency. And when the installation is in an attic, it's very hard to get a good ground connection, the main reason is that you will get a lonnnnng wire from the Kiwi to the ground and this grounding wire will also be an antenna and will be able to have a resonnance behaviour. For example, a 5m long ground wire will be lambda/4 on 20meters and will be totaly unusable.

    The power mains safety ground must NOT be used as it carries all the leakage currents of all the switching mode power supplies of the house, and can be several volts above ground.

    I would want to ground my kiwi antenna common-mode blocker for example, but just under the roof it's not easy.

    73's de J-Luc

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