In message <Xns98DE3A21981701A4D@127.0.0.1>
Mozzy <demo@account.com> wrote:

> What screening is necessary if I want to protect a domestic-grade
> electret microphone from the RF coming from a cellphone which is in use?
>
> I sometimes hear radio or TV news broadcasts which still get cellphone
> interference so I would guess it is not all that easy to provide a
> reasonale level of screening.
>
> On the other hand, you can get a cheap electret microphone designed to
> be worn in the ear (as a phone-recording microphone) which is remarkably
> resistent to cellphone RF.
> http://www.teknikmagasinet.se/prod/s...png/290080.png
>
> How do I make a domestic electret microphone capsule with its co-ax
> microphone cable (cdonsisting of shield and one core) resistent to
> cellphone RF?

It is exceptionally unlikely to be the microphone that's causing
the problem; it will be the electronics that it's connected to
that is demodulating the signal, and therefore that needs to be
filtered and/or screened.

Unless you understand electronics fairly well, it's difficult or
impossible to explain how to do this. If you /do/ understand
electronics, then the best hint is to beware of the inductances
of even short lengths of wire. Surface mounted components and
tiny track lengths are your friends.

Dave