If you've ever turned on your computer and your radio went to static or had your computer speakers buzz and cut out before receiving a cellular phone call, you've experienced radio interference with a PC. Interference, indicated by a buzzing sound, static or service cutout, is caused when the computer and other devices operating on the same frequencies. Radio interference with PCs can work both ways: the computer can interfere with other devices, and other devices can interfere with the PC. Nailing down the exact cause of interference can be time consuming or inconclusive.
Disconnect any unnecessary components and peripherals from the computer to eliminate as many interference-causing parts as possible. For example, disconnect unused speakers, network adapters, printers and input devices; anything with a current could be the cause. If the interference dissipates, use the process of elimination to determine the guilty part.
Connect the computer and the interference-suffering device to different electrical sockets. Bad wiring in the wall could be causing the interference and not the device itself. If the devices interfering with each other are connected to the same outlet, try moving one to a different outlet.
Create as much distance as possible between the PC and other interference-causing or receiving devices. Computer-related interference may affect only devices that are close to each other.
Tie up long cable slack or replace long cables with shorter cables. Cables and wires are more prone to radiation interference than actual circuit boards. Minimizing cable space decreases interference.
Install EMI ferrite coils on cables and wires. EMI ferrite coils act as a choke point for radio frequency interference and can stop devices from interfering with each other. The computer's power supply is the likely culprit; however devices like the keyboard and monitor have large unshielded areas prone to interference.
Use computer speakers that feature an electrical ground and have shielded wires. If the speakers aren't grounded and shielded, they can be prone to picking up any nearby transmission.
Change the router's Wi-Fi broadcast channel. Wi-Fi operates at a much higher frequency than other radio devices, but may interfere with things like baby monitors and cordless phones.
Turn on any nearby microwaves and check the PC for interference. Microwaves are notorious for causing interference. Either move the PC away from the microwave or avoid using the microwave while using the PC.
- While interference can be annoying and complicate getting devices to work right, it won't physically damage devices. Shielding the computer case is an option if interference is causing major problems.
- Removing internal computer components risks damaging the computer. Skip removing internal devices if you're unsure of what you're doing. Since interference troubleshooting is a process of elimination, you risk spending money on interference eliminating devices that may not solve the problem.
- Cnet: FAQ: The 411 on Radio Frequency Interference
- ARRL: Computer Interference FAQ
- Popular Mechanics: How to Fight RF Interference with your Gadgets
- FPL: Solving Electrical Interference Problems
- Universal Radio Inc: Amidon, Inc.
- Digi-Key Corporation: RF Shielding: The Art and Science of Eliminating Interference
- Digital Vision/Photodisc/Getty Images