I am getting GSM Buzz on a wireless micrphone system. The interference is coming from the Micrphone itself as it is transmitting it in the audio and is not being caused by direct RF interference with the transmitter or receiver.

This is an RV2 wireless sytsem from EV (uses TELEX equipment). The unit in question is HTU2 microphone (HT-500 bosh/Telex).

When a GSM phone is held close (with in 1') and the phone receives a SMS you hear the pit pit pit sound of the SMS/GSM packets being sent/received.

I am was thinking I could shield the microphone and internal components and just make sure I didn't shield the antenna area (couldn't find the actual antenna -fcc:B5DH219 docs say its TP11 but didn't see any antenna in that area).

At this point I see there is an RF choke at the mic input, but I am left wondering if Ferrite beads added to the mic input wiring would work to solve the problem. All the other answers speak about using ferrite beads on the wires going to the receive but none talk about put microscopic ones inside the wireless microphone itself.

Anyone have experience in eliminating hte GSM noise from the Ev RE2 Clear Scan units? The noise persist on any frequency the units are set to.

I have seen other post such as Why is GSM interference audible? Why does GSM cause speakers to buzz? Killing GSM Buzz with Ferrite Beads

  • \$\begingroup\$ Can you give us some photos of the insides of the unit? It sounds like the internal wiring itself is picking up the RF and delivering it into low level audio stages, where it's getting rectified, but I'd need photos to see where to stick beads/... \$\endgroup\$ Sep 10, 2016 at 3:15
  • \$\begingroup\$ I was unable to get pictures as the client's location and equipment are in a secure area that did not allow cameras. The adding of the Ferrite beads eliminated one source of noise which happened to be from an Ozone Air purifier left in a storage room next door. It was improperly shielded and was arching to the ground. After this was corrected the ferrite beads didn't solve any other issue. \$\endgroup\$
    – ben
    Mar 11, 2021 at 20:51


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