Written by Troy Reit
In part one of Fixing Wireless Microphone Dropouts we covered the importance of using the correct antennae, placing them correctly, and avoiding metal objects that can interfere with wireless transmission. In part two we continue with three more ways you can potentially solve wireless dropout problems.
4. Avoid Antennae Farms
We’ve all done it. I remember years ago the piles of wireless receivers at my church, stacked on top of each other with the ½ wave antennae nearly touching each other, but with each delicately positioned just fractions of an inch from its neighbor. The issue is that when you put antennae close together like this, they interfere with each other, causing inter-modular distortion. Any two antennae should not be any closer to each other than the mounting ports on the back of the receiver will allow. Most receivers are a ½ rack width, meaning no antenna should be within 9 inches of any other antenna. That’s not possible when the receivers are stacked on top of each other.
If you have more than two wireless receivers, you should be using an antenna combiner. This is a common device that allows up to 5 diversity receivers to share only two antennae. They can also be cascaded to allow more systems to share the same two antennae. All the signal amplification (and often power distribution for receivers) is built in to the unit, simplifying installation and cleaning up the cabling. This also allow systems to be installed easily in a rack. The same holds true for wireless in-ear systems. If you have more than two, you should be using a combiner with the correct antenna to keep the systems from interfering with each other.
Shure Antenna Distribution System
If you use wireless receivers and in-ear transmitters in close proximity, use longer extension cables to get their antennae as far apart as possible. An in-ear transmitter is a high-power radio frequency transmitter and the wireless receiver is a very sensitive radio frequency receiver. The in-ear system’s transmission antenna should never be pointed at the wireless receiver’s antenna. If you use cables longer than a couple of feet to remotely mount your antennae, be sure to use low-loss cables supplied by the manufacturer. Radio frequency signals are prone to significant loss over distances, even short ones, so special low-loss cables are required along with signal amplifiers to get adequate signal from the antennae to the receiver.
5. Keep Your Batteries Fresh
A weak battery is the most common cause of signal loss. Batteries are cheap, especially with the newer transmitters that use AA instead of 9V. There is no reason not to change the batteries before every performance or church service. If you don’t like the effect on the environment, there are some excellent rechargeable systems available. Shure’s rechargeable battery system is a good example. It has a fairly high up-front cost, but the lifetime of the battery more than makes up for it, and the batteries last far longer than the standard alkaline. Almost all modern receivers will tell you the health of your batteries, and good receivers will connect to your network to allow you to monitor them remotely.
6. Get Out of 600MHz
The recent FCC auction of the 614-698MHz band means that many wireless systems will become illegal on July 13, 2020. Before that, the new owners of those ranges (mostly T-Mobile and Dish Networks) will turn their equipment on in certain areas and start using those frequencies. When they do, any wireless audio system in that area and range of frequencies will stop working or have serious interference issues (As of this writing, T-Mobile is now broadcasting in the 600Mhz band it is causing major interference with wireless systems). In addition, any device caught transmitting in that range after July 13, 2020 could see fines of up to $1200 per device per day, whether it was in use or not.
The good news is that manufacturers are offering rebates on 600MHz gear when you replace it with new gear in a legal spectrum. For example, if you buy a Shure QLXD system and turn in the old system (from any manufacturer), Shure will give you a $250 rebate, but only through October of 2018. If you’re curious what kind of rebate you would qualify for, just click here and fill out this quick form.
Conclusion: When you understand the technology behind the wireless devices we use, it becomes easier to troubleshoot dropouts. Follow the guidelines in this article to clear up your wireless dropout issues and don’t be afraid to reach out to your local dealer to ask for help. VIP Production Northwest provides free consultation services to help you get the most out of your wireless (and other) gear.