Two RFI sources identified

As I live in a suburban location with a small garden there are practical limitations as to what antennas I can put up. The Wellbrook Loop (model ALA100LN) hears very well over a wide frequency range and I can’t think of another antenna that would perform as well within the defined space. Further improvements to receive performance must therefore come from other areas, specifically noise reduction. Several measures have already been taken as mentioned in previous posts, but new discoveries continue.

First, a wideband noise source was noted from time to time. Observation of domestic activity identified this as bathroom ceiling lighting which consists of six 12V halogen bulbs.

As the interference was very infrequent and of short duration, no rectification action was taken.

Secondly, after a computer reconfiguration was performed, it was noted that the level of Ethernet RFI had increased. Ethernet connected devices were disconnected and then reconnected one by one while observing a particular RFI pattern just below 28 MHz. It was found that one PC – a generic Core I3 desktop machine by Compaq – had a really noisy Ethernet connection. As this computer runs multiple WSJT-X monitoring processes it works 24/7, but only uploads small amounts of data when decodes occur. In this case, conversion to a Wi-Fi dongle and disconnecting the Ethernet port was sufficient to solve the problem.

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