Shure PA411 Antenna Combiner

The PA411 exists to solve a specific and familiar problem: you've stacked four PSM 300 transmitters in a rack, and now you have four whip antennas crowding the top of the case, coupling with each other, and generating intermodulation products that show up as dropouts in the worst possible moments. The PA411 combines the RF output of up to four PSM 300 transmitters onto a single antenna path, letting you feed one well-placed directional antenna — typically a Shure PA805 or similar — instead of a cluster of omnis arguing with each other. It's a 1U half-rack unit, so it pairs neatly with a fourth transmitter in the same rack space.

At 5 watts nominal draw and a shallow 150mm depth, the PA411 adds almost nothing to your rack's footprint or power budget. What it does add is RF discipline. Running four transmitters through a single combined output means your antenna placement becomes intentional — you're aiming coverage rather than hoping four whips average out to something useful. On a theater gig or a festival IEM rig where the drive distance between the rack and the stage is real, the ability to run a single quality cable run to one directional antenna is practically worth the unit's price on its own. The combiner is active, so it requires power, but at under 8 watts worst case, any standard rack conditioner handles it without a second thought.

If you're running two or three PSM 300 channels and they're working fine, you probably don't need this yet. But the moment you hit four channels and start chasing intermittent dropouts, or you're building a rig where the antenna has to be remote from the rack, the PA411 is the right answer and not an optional luxury. It's specifically designed for the PSM 300 ecosystem — don't assume it's a general-purpose combiner for other transmitter families. If your rig is built around PSM 900s or a mixed-manufacturer system, check compatibility carefully before buying.