Common Mode Noise Filter – Coax SWAN Electronics Transceiver RFI Kits Store / SWAN Electronics Transceiver RFI Kits SWAN 250, 350, 400, 500, 700 Transceiver RFI Kit - 4 RFI/Noise Reduction Filters SWAN 250, 350, 400, 500, 700 Transceiver RFI Kit - 4 RFI/Noise Reduction Filters SKU RFI-SWAN $34.95 Buy Now Typical user comment: The filter was quite effective. Was surprised that it actually reduced the noise level more than the signal so S+N/N improved by 1.9 S units. Bill