radio interference on a hardwire

Posted: Sun Feb 17, 2008 12:27 pm

I just encountered a problem on set where I was getting a very loud radio station on a hardwired microphone.

Any clues on how to avoid in the future?

Posted: Sun Feb 17, 2008 3:26 pm

All. your cables balanced and shielded? Maybe a pin 1 prob in a piece of gear or look for any other lines running close your your connectors.

Could try to throw a line conditioner in front of your gear as well or maybe some iso plugs.

Hope this helps.

Posted: Mon Feb 18, 2008 5:34 am

A while back I made a set of in-line XLR interference suppressors for just this sort of problem. I haven't got one here at the moment to look inside, but if I remember correctly I put series absorption ferrites at the signal input and common-mode ferrites at the output. Between the two sets of ferrites were delta capacitors to shunt residual r.f. to ground (shell, not pin 1). Since making the suppressors, I have never encountered an r.f. problem that they did not knock on the head.

Something to check first, though, is that XLR pin 1 on the microphone does actually connect to the microphone body and that pin 1 really is grounded at the pre-amp.

Posted: Mon Feb 18, 2008 10:17 am

Did you try simply swapping the cable?

Sometimes the easiest fixes are the most often overlooked.

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