wrote:
Here's the situation: Sometime last year, we got a scope after some
begging by a tech. He then said that the cell tower out back (somewhere
between 50-100 feet away) was causing interference. He quit, and the
other 'tech' working in the shop was fired. Now that I'm in there, the
'boss' wants the scope out and working, but all I hear is, "Oh, that
doesn't work" from a couple of people.

Now, I have very little experience with scopes, and think that possibly
this is a grounding problem, or of course, there is a need for
shielding, or knocking down the tower itself. The scope is used, and
probably around 20 years old, and looks like this:
http://dustbunny.physics.indiana.edu...pes/t475_c.gif
, the Tektronix 475.

Any suggestions on shielding the interference, or testing to make sure
of the existence of local interference?


Didn't see any mention of the MAGNITUDE of the interference.

I'd been using 50 MHz scopes for decades. Got a 500MHz one and started
seeing low level noise. Punch the FFT button and I can see every FM and
TV station for miles around. It's coming in the probe. Hooking the
ground clip to the tip doesn't help. Shorting the tip directly to the
tip ground fixes the problem. Ain't nothing to be done.
If your probe is broken, the problem can/will be much worse.

The cell tower may not have anything to do with what you're seeing.
There may be other stuff besides cellphones on the tower.
I'd borrow a spectrum analyzer.
mike


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