Cell phone RFI problem

[diko2]

Hi everyone,

I've got a EZ1073 follow by a Mnat 1176 (separate cases) that i use on a lead vocal during live shows.

It sound fantastic and i'm very happy with it.
But i' ve got some random cell phone RFI issue.

The mic is a KMS 105. The signal is split with the monitor desk, then it goes to the 1073 then to the 1176 and then to my desk.

The 1073 and the 1176 got only "classical IEC socket" (with no filter). So i put a EMI/RFI filtered power distributor in front of them. But i still have randomly cell phone sound.

Can someone point me where  i should look?

1/ can it be the two power chords between the distributor and the iec sockets that catch interference?
2/ Can it be a bad grounding?
3/ Or a bad case shielding?
4/ Can the 600 ohm termination option of the 1073 be part of the problem (or solution)?
5/ Wich part of the shematic is sensible to interference?
6/ How  a  x Ghz frequency can affect my audio patch?

Thanks

Morgan

 

[joaquins]

You only have when you have both things connected together or any of those makes the same in any other conditions?

6- Some HF random noise is going into some active component that can't catch up with the speed of the signal, it goes as fast as it can and some noise in the audio band is produced.

For all the others, I would look for grounding and wiring between both rigs, I assume your interconnection is balanced, and you have both chassis grounded via the mains socket, so maybe what is usually called pin1 problem, quick fix turning out or the mains ground connection of one of those (not recommended) or lifting the shield of the cable between both units. This could give you an idea but you should make it good and add a proper ground lift at the input of the 1176 with RC and a few diodes, so is still safe and less ground problems.

Input filtering may be bad in any of them, but that would cause them to make the same thing in different conditions which I asked up there. There may be other things going on, but if you get a cell phone interference each time you have a call you could make your phone ring from a friend's one and move it around to see where it's worst, then you have where the problem is coming from... I hope that helps.

JS