What's riding on my 60Hz AC? I want to find out

From: Norm Dresner (ndrez_at_att.net)
Date: 07/12/04 

Date: Mon, 12 Jul 2004 17:05:28 GMT

I want to be able to look at the HF content on my 60 Hz AC main supply --
the first use is because I want to see exactly what frequency a "wireless"
intercom is using but I'd also like a general capability for later.

I first thought of using a small transformer to lower the voltage down below
the level of lethality (say 12.6v RMS) but I'm fairly sure that the
inductance in the primary of a transformer would suppress any HF content;
isn't this so?

Then I thought of using a capacitor and an inductor as a frequency-variable
AC voltage divider. Literally back of the napkin calculations produced a
design of a (roughly) 470 nF capacitor feeding a 1 mH coil with the output
taken from the junction of the two.
Is this (a) feasible?
            (b) reasonable?
            (c) safe enough if I follow the Primary Rule of HV Circuitry [*]

Many other values are available but that's what I remembered having in the
parts ox while I was at the resturaunt.

If this is a stupid idea, I'd sure like to get some informed suggestions.

TIA

    Norm

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