Audio problems with Panasonic HVX-200

Hey Ty - it's been a little while since I've posted here.

I've been doing some work recently with a local studio that shoots with the Panasonic HVX-200 P2 camera (using P2 media). I did a job for them today and heard a low level "beeping/chirping" sound in the return audio from the camera. The audio is clean when I am monitoring in standby, but as soon as the record button is pressed, the beeping/chirping begins and, worst of all, is recorded into the file (I was hoping for a headphone amp issue). It's very rhythmic, about once/second, and consistent in level. It's a low level noise, in fact so low that the producer/videographer could barely hear it and didn't can the shoot because of it. We did spend 15 - 20 mins troubleshooting, trying different input settings, different outputs from my mixer, connecting the mic directly to camera (bypassing the mixer), etc. all to no avail. I'm pretty sure I'll be able to notch filter it in post (if needed) so I'm not going to lose any sleep over this, but I do want to see if anyone else has had this issue with the HVX series cameras. I'm not familiar enough with the menus on the HVX to know if there is something I'm missing in the camera, but I'm thinking that's not the issue. We did two shoots today - one HD, one SD, both with the HVX-200 and both had the beeping/chirping.

My equipment today was Schoeps MK41 mic overhead through a Sound Devices 442 feeding a single Panasonic HVX-200.

I've tried to list all pertinent information, but if I've forgotten something, please ask. I'd like to figure this out.

Thanks to all who post.