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RFI Cable Cleanup with TinySA

rfi cable cleanup

TinySA is a perfect tool for RFI cable cleanup. Make sure your supposedly shielded coaxial cables running between antennas and radio receivers are actually shielded.

As I was preparing to test my collection of analog noise reducers, I thought it wise to ensure that my connection cables were not adding any RFI within the shack. Turns out this is a perfect job for the TinySA spectrum analyzer.

Not all cables are created equal when it comes to connectivity and shielding. Often a poor crimp or solder of a connector can cause leakage. Similarly, some shields get broken. While a typical shield effectiveness on a length of RG6 should provide 70 to 90 dB reduction of RFI ingress, often you can cut that figure in half or even less.

TinySA is very useful for RFI cable cleanup. You can connect the TinySA Low port and set frequency range to 30 MHz or so. Then, monitor the RFI on the cable as you disconnect SMPS or cycle monitors and computers and other equipment on and off. Nice thing about the battery powered TinySA is that you can disconnect all sources of power without interrupting the spectrum display for a particular cable.

As you can see above, one of my cables is carrying RFI above 10 MHz at -60 dBm or so. This is 30 dB higher than the typical noise floor of -90 dBm on this spectrum analyzer.

By swapping in a different cable, I made the RFI ingress disappear. By the way, you can also use NanoVNA for testing cable continuity, but the TinySA is the tool for checking shielding effectiveness. I promise you may be surprised by what you find with the TinySA!

RFI Cable Cleanup – Patch Bay

As part of my RFI cable cleanup efforts, I also re-worked my patch bay. In the top row, you can see the BNC connections to my receivers. This includes the dual channel RSPduo and Afedri radios, as well as Perseus and Flex inputs (I use Antenna 2 for receive only.)

Along the bottom row are the three connections for the RFI elimination boxes (Main and Aux inputs, and output to receiver) as well as lines to the Noise Probes and Main antenna switch.

Finally, I sprayed some conductive paint over the plastic patch bay and connected the whole thing to my station ground. All of the antenna cables now share a common ground.

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