Electronic devices (cell phones, radios, headlamps, MP3 players, GPSs, etc.) can affect avalanche transceivers. The electronic devices affect the searching beacon more than the transmitting beacon.

Most manufactures of electronic equipment do not mention possible interference between their electronics and avalanche transceivers. However, a few diligent manufactures, such as Petzl, mention avalanche transceivers specifically. This note that comes with the Petzl Tikka XP2 headlamp: "Warning, when your lamp is lit and in close proximity to an avalanche beacon in receive (find) mode, it can interfere with the operation of the beacon. In case of interference (indicated by static noise from the beacon), move the beacon away from the lamp until the noise stops, or switch off the lamp."

In search mode, irregular readings and decreased range can also be caused by other sources of electrical interference, such as power lines, lightning, and electrical generating equipment. Chairlifts also generate background "noise" that can affect the searching transceiver.

It is preferable to turn off your electronics when transmitting so you don't forget to turn them off when searching. (Consumer electronic devices haven't been shown to interfere with a beacon's transmissions.) If it is not practical to turn them off, always keep them at least several inches away from your transmitting beacon. Metal objects should also be kept away from your transmitting beacon (e.g., pocket knifes, additional transceivers, etc).

When searching, the electronics and metal objects should be further away from your transceiver than when transmitting.

• The Tracker DTS manual says at least 15 cm (6 inches), The Tracker2 manual says at least 30 cm (12 inches).

• Ortovox has always said to keep their transceivers at least 30 cm (12 inches) from other devices. The Ortovox 3+ owner's manual says 50 cm (20 inches).

• Mammut says at least 50 cm (20 inches).

• My informal testing leads me to feel that the Tracker2 and Ortovox recommendations of 30 cm (12 inches) is a reasonable minimum. Of course, it is best if you turn the devices off (which is what most manufactures suggest), but turning off radios and cell phones during a rescue is not always realistic.

Remember that a cell phone that is not being used still transmits a signal to the cell service periodically (I have been told that this occurs every 3 to 15 minutes). 

Some transceivers use a magnetic compass while searching (e.g., Mammut Pulse and Ortovox S1). It is especially important that you keep magnetic items away from these transceivers while searching. Be especially wary of magnetic closures on jackets.

Some transceivers use a magnetic switch. It is possible, although not easy, to switch between Off, Send, and Search with an external magnet. The transceiver will return to its previous mode when the magnet is removed. This is another reason to avoid jackets with magnetic closures.