Mobile Station RFI Kits

Does the operation of a treadmill or your exercise equipment wipe out your radio receiver reception? We have heard cases where the treadmill from a neighbor’s house wiped out the ham radio receiver reception from 2-30 Mhz! The treadmill source was finally isolated to a variable speed motor power supply that was injecting RFI into the AC wiring of the house and the AC wiring was acting as a transmitting antenna broadcasting the signal to the entire neighborhood. The case was difficult to track down since the broadband RFI interference only occurred at 7-8 pm each nite when the neighbor used the treadmill. As with all RFI cases the sequence is similar: Find the Source, Choke the Path, Protect the Victim.

Once the source was identified, a simple solution was to choke off the transmitting antenna with a AC line choke shown below which eliminated the interference problem to the ham receiver:

Testimonials

F400-31 AC Power Cord Choke completely cured the RFI problem I had with my wife’s treadmill. Now I can hear the weak signals!

73,
Jim K4AXF
Icom IC-725
Grottoes, Shenandoah Valley, Virginia
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Mobile RFI kits work two ways: They suppress RFI from on board computers and other sensing/control devices in your vehicle that may cause your radio to be a VICTIM of RFI, and second they suppress RFI generated by your radio as a SOURCE which may affect your on board computers or other devices.  Mobile operations of HF radios (1-30 Mhz) tend to experience more RFI effects than VHF/UHF mobile stations.  If you have both HF and VHF installations in your vehicles, you may need both kits.

To address separate solutions we have developed two separate RFI kits: one for HF (1.8-300 MHz) mobile installations and another for VHF/UHF (30-1000 MHz) mobile installations.  Each kit uses the appropriate ferrite mix for the frequency range desired.