Home Alarm System RFI Kit
RFI-ALARM Home Alarm RFI Kit
This RFI-ALARM kit is specifically designed to cure most alarm systems triggered by Radio Frequency Interference problems. The kit contains ferrite toroids (“Donut” shaped ferrites) including a snap on ferrite for AC power supply protection and smaller toroids for alarm sensor lines selected to eliminate RFI from 1 to 1000 MHz. The ferrites are easy to use, don’t require modification of the protected equipment and work in almost all cases.
What causes RFI?
Strong signals from nearby amateur radio, CB, FM and other “transmitters” (such as microwave ovens, cell phones, desktop, laptop, and tablet computers, wireless phones, baby monitors, fish tank heaters/pumps, etc) that are picked up by long wires (“antennas”) running through the house electric power wiring, telephone cables. alarm system wires, speaker wires, etc. These “antennas” feed the interfering signals into the TV, telephone, stereo, alarm systems and computer modem causing them to halt operation or act intermittently.
How to cure RFI
RFI can be stopped by suppressing the signal from the radio “transmitter” or suppressing the signal on the receiving “antenna” feeding the affected device. With the RFI-3 kit, you run the wires entering the alarm system through ferrite cores right next to (or inside) the alarm box (see RFI Tip Sheet for additional example installations). Ferrites do not affect the signals going through the wires but they resist the passage of common mode RFI keeping the RFI signals out of the alarm and stopping the RFI from falsely triggering the alarm. Some sensor lines may require multiple ferrite toroids to be most effective. Also the more turns around the toroid, the more effective the RFI filter.
What is included in the kit?
The RFI-3 kit is meant to be used with a AC powered (possibly through an AC wall wart or inline dc power supply battery backup) alarm system with up to 34 input/output signal lines (including the central office telephone monitoring line) and a single power supply line coming into the device. Included in the kits are five sizes of ferrites including: toroids/beads in size F50, F63, F82, and F114 to accommodate various wire/sensor sizes and a FSB31-3/4 for the AC line/DC cord. Full instructions and pictures of a typical installation included in instruction manual.
TECH NOTE: We also stock RFI kits to protect effected devices such as garage door openers, computers (laptops, desktops), dsl/cable routers, ethernet hubs and many more devices. If you run a high powered RF amplifier in your ham station also consider a linear amp RFI kit which will cut down RFI transmitted by your station. Remember there is always a “transmitter” and a “receiver” of RFI and the quest is to find and choke the “path” the RFI has selected – you need to add ferrites to both the transmitting side and the receiving side to eliminate RFI problems. The RFI kits on this page only helps suppress RFI on the receiving side.