Any chance these systems have operating frequencies >608.000 mHz? Have any local TV stations finally "moved" RF channels in compliance with the broadcast RV re-pack of 3 years ago? (more bkg below)
Are the transmitter pack antennae touching the performer's skin, or might they be folded/caught between the transmitter case and body-side of the transmitter pouch/belt? Are the transmitters under costumes with metallic thread (or aluminized
Mylar®)?
This story goes back to the original digital TV re-pack about 15 years ago that allowed the FCC to comply with a Congressional mandate to make the 700 mHz band more financially productive, history thereof: the FCC auctioned 10 year licenses to "the usual suspects" in mobile communications - ATT, T Mobile, American Tower, Verizon, and some smaller players. Some TV broadcasters changed RF frequencies, some only changed modulation and input for digital video and the more effective use of each TV
channel's RF territory. Lather, rinse, repeat for the 600 mHz band, the TV re-pack began 4 years ago (and hence my question about operating frequency) and was slowed considerably by Covid-blamed supply side issues with various parts of broadcast hardware.
It was in the 700 mHz re-pack that a local youth musical theater company got tripped up. Local TV 10 had to change RF frequency (they kept the virtual dial
channel number) down into the 600 mHz band, where the company had several channels of fixed-frequency wireless systems. Packs 1 & 2 were the female and male leads, respectively. Every time the male would be
stage right, facing
stage left, his signal would
fade away, sometimes rather abruptly. When he turned to
face stage right or
downstage, his mic would quickly feed back. As the mixerperson, this was Not a Good Thing for my reputation... and I was getting what sounded like a bad mic cable on one or more of the PCC-160 floor mics. The long troubleshooting process
led to these conclusions: 1) The center of TV 10's new RF home was the frequency of Pack 2; receivers (all 1/4 wave antennae, receivers stacked up, a seriously compromised situation on its own) were
stage left, by the SM, and when the actor's body was between the Pack and them, the TV 10 transmitter was strong enough to desensitize the front end of the receiver but when the pack RF was strong enough, it all worked after the receiver wasn't saturated. 2) the intermittent "bad
ground on a phantom powered mic" like the PCC-160s... was an IM hit of RF when Pack 1, Pack 6, and Pack 9 were on
stage together, and only in certain physical places w/r/t each other. 3) I developed a strong dislike for the vacuous use of RF for video content delivery (we lost precious, unlicensed spectrum so folks can watch Real Housewives of Steaming Video and live stream their karaoke performances to
Face Space, bah AND humbug, but I digress).
/little story
So... if your wireless mics operate above 608 mHz, you're likely getting RF hits from T-Mobile / ATT/ American Tower transmitters on their LICENSED frequencies. If you're down in the 500 mHz band, it's possible that a re-packing TV station got their back-ordered antenna/transmitter put on
line since your previous show and you need to do a new coordination. While it's possible for land mobile (police, taxi, business) services to interfere, in all but the large metro areas they aren't a significant factor. OTOH one of the venues I routinely work is 2 miles from an airport with significant RF testing and development for aviation (weather radar, a variety of open and encrypted communications, navigation and remote operation) and as far out-of-band as they may be relative to 500mHz... they DO have an impact and it can vary with whatever devices are under test at Honeywell or Textron or Bombardier. Tiny story (Honest!) - about 8 years ago, Beatles tribute act is playing their first show with IEMs (the Beatles did not have
wedge monitors). "George" says "well, it will be lovely once you turn off the flanger in my head." Wireless Work Bench wasn't much help; I think they randomly retuned his receiver until the noise went away and then coordinated the other 3 with that frequency. /tiny story