Wire-Lists#7: Cold Weather Care for Transmitters, Mics and Receivers

It’s Winter time again! And unless you live in a tropical climate, Winter means one thing: COLD. Regardless of the time of year, many of you also run sound in perpetually cold locales, such as the Arctic Circle, Siberia or Mongolia. Contrary to popular belief, electronics, unlike Husky dogs, don’t actually like the cold. Your transmitters and recorders can deliver reduced performance and even fail to work below certain temperatures unless you take precautions. Here are four areas to pay attention to when operating or storing your equipment over the next several months:

LCD Displays

LCD displays – such as the ones on our transmitters and receivers - use liquid crystal fluid (more like a gel) in the display. Like all other non-solids, the liquid crystal can freeze in cold conditions. Ideally, you should store any equipment with an LCD display in consistent temperatures between 40° and 100°F to keep the liquid crystal from freezing.

What happens if you’re working in extreme cold – such as an outdoor location shoot with wind, snow and ice? Even if you had stored it in a warmer area, the equipment will invariably get colder as you work. When the surrounding air reaches the freezing mark of 32°F and below - equipment will still work, but you may notice the display responding much slower than usual.

Batteries

A side effect of cold is reduced battery power. Why? Because batteries create power through the flow of electrons from one terminal to another. In cold temperatures, the internal resistance increases and this flow slows considerably, making the battery output more power than normal to power your unit. For example, at -4°F , most batteries will be at 50% of their normal performance level. This results in batteries that don’t last nearly as long as you expect. One way that you can somewhat circumvent this is to replace the batteries at the end of each cold workday, which makes sure that you are starting off each day with fresh power. This is a best practice for your workflow regardless of the temperature. Our FAQ that discusses the effects of cold weather battery issues in detail: I don't get much battery life in my transmitters when they are cold. What kind of batteries should I be using this winter?

Circuit Boards

Circuit boards can also be damaged by cold, because they expand and contract with temperature fluctuations. Over time, this can cause poor connectivity at the board level. Condensation is another killer for cold electronics in areas with high humidity. When you bring a vented unit into warm, humid air after it has been sitting in the cold, the condensation can be bad enough to cause electrical shorts on circuitry. We have never seen this issue with regard to our products, but that doesn’t mean it couldn’t happen. Do you want to be the first it happens to?

Cables

Cables can get stiff and brittle in the cold. They will still work as designed but will be a bit more fragile. Any additional stress on a cable also stresses the wires inside.

6 Ways To Prevent Cold-related Malfunctions:

1. When you bring equipment out of the environment in which they are stored, do so gradually, so that the display can acclimate to the ambient temperature. A good rule of thumb is to let the unit acclimate for a minimum of 4 hours before turning it on.
2. To prevent any chance of circuit board damage from condensation or expansion/contraction, again, acclimate gradually.
3. If your equipment rides in a bag set-up, consider using portable hand warmers (like the type you use in your pockets for winter sports) inside the bag. Place them in proximity to, but not near or touching the unit. Another low-cost insulator is newspaper.
4. If they’re being used on talent, bundle transmitters between layers of clothing to trap body heat. Do not put them on bare skin, as skin will deposit moisture and oils onto the unit. When it is cold, bodies actually sweat more, not less, in the effort to regulate body temperature.
5. If your cables are going to be in freezing temperatures for a period of time, avoid excessive flexing if they are already stiff. If you have the budget and find yourself in this situation often (like documentary filmmakers or those that run sound for outdoor events), your best bet is to purchase thicker cables that are made for use in the cold. Loon Audio makes a great coiled cable that is lauded on a few of the sound tech newsgroups.
6. This last tip is critical: Before going from the outdoors to indoors, put any equipment that has metal parts (recorder, transmitter, mic) into a Ziploc baggie with silica gel pouches while still outside. Close it with as little air as you can (squeeze the excess out before you zip). You can even put the Ziploc into another and close that – it works like an airlock. Bring it inside and let it rest 15-30 minutes before you put it away (remember to remove the batteries). The silica gel will absorb any humidity, preventing it from condensing on the cold metal.