[sdiy] 100 MHz EMI, what can it be?

[jhaible]

>107,0MHz or 107,7MHz FM , 500W
>
>directly in my neighbourhood.
>
>Do you see something like this with your local
>FM stations?
>

I have once traced some "oscillation" in an Emu filter
for hours, until I noticed it came "from the air".
Why?
It was my first time to use LM318 opamps, so I didn't
trust them. And the circuit was so clean that I saw
a periodical signal where in other circuits this would
have been below noise.

JH.




-----Original Message-----
From: René Schmitz [mailto:uzs159 at uni-bonn.de]
Sent: Montag, 14. April 2003 12:01
To: Czech Martin
Cc: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] 100 MHz EMI, what can it be?


Could that be be a FM radio station? I would check with a
receiver what that signal is.

Cheers,
  René

Czech Martin wrote:
> If I connect the (long) ground clip of the oscilloscope
> probe to the tip, I get a nice loop.
> I can see 10 mVpp, around 100MHz. No matter how I orientate the loop,
> it will not disappear.
>
> What can this be? Computer is of, cell phone is much higher,
> wireless phone should also be higher.
>
> Of course, connecting the probe tip to shield via 5mm wire
> will make the noise disappear, so it is clearly something
> from outside the scope.
>
> I live near a railway track, is this railway communication radio?
>
> m.c.
>
>

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http://www.uni-bonn.de/~uzs159