[UPDATE: it seems the ZAPD-1+ is currently out of stock. RF Venue sells a passive splitter that does the same thing. It's in stock. Contact us for pricing.]
Here are three simple and low-cost wireless audio antenna distribution configurations using the Mini-Circuits BNC ZAPD-1(+) passive splitter/combiner—a versatile accessory we’ve used for years to build affordable wireless racks in conjunction with our antenna combiners and distributors.
For some reason, there is a rebranded ZAPD-1 floating around with a ludicrous retail as high as $700. The exact same splitter can be purchased direct from Mini-Circuits for $60. Navigate here and click "ordering..." top right, in red.
Homebrew 8 Channel IEM combiner
This setup effectively creates an eight channel combiner for much, much less than a standalone active 8 channel transmitter combiner.
Were we building this kit out for a customer, it would look like this:
Passive intermodulation could potentially be introduced under less than ideal circumstances with this setup, just as it can occur at other physical connections throughout the RF chain.
But, if frequencies are properly coordinated, and the splitter in use has good isolation between ports, harmful harmonics are not likely to occur.
Never use an active combiner in place of the passive ZAPD-1+, and never directly connect two or more IEM transmitters directly to a passive splitter/combiner like the ZAPD-1+.
There are some engineers who prefer to use two or more four channel combiners with dedicated antennas, as a measure of redundancy. That’s fine, but remember to space active antennas a good distance apart to avoid near-field interactions that may result from antenna farming.
Diversity Fin DAS
Here’s a request we get all the time: “we want the same wireless microphone to function across two or more rooms.”
We use two Diversity Fins and two ZAPD-1+ to accommodate those requests.
In effect we create a simplified DAS, or distributed antenna system. In a DAS, talent freely wanders through a series of coverage “zones” without fear of losing reception. Signal sent to the same receiver(s) or different receivers depending on the engineer’s design.
Distributed systems can get complicated. That’s why we leave the bulk of the expertise in this area to Professional Wireless, who specialize in DAS.
Spectrum analyzer "wiretap"
Simply place the splitter in-between one branch of one output of a distributor. Feed one of the splitter’s outputs to the analyzer, and return the other output to the receiver.
The goal is visualize RF from the perspective of the receivers. The nearer the tap is to the final destination of the signal, the better the data the analyzer can retrieve for you, since it is seeing what the system is seeing.
This setup is great for taking a peek at RF activity from the system’s perspective, and for troubleshooting RF where an ambient scan has not revealed anything, but it is generally not recommended for routine operation.
The splitter adds one additional point of failure to the signal chain, and poaches a few dB of amplitude, changing the receiver’s interpretation of the two diversity signals.
If you want to do a wiretap during actual performances it’s much better to tap from an unused output on a distro, or on the cascade output of the final distro in a daisy-chain.
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