[Lowfer] Hz question.

[Jim McClanahan]

I doubt you would see much. I've tinkered with powerline communications like X10 
and such. You can use a low value (but high voltage rating) capacitor to couple 
to the powerline if you use a low-inductance coil as a "drain" between the radio 
side of the capacitor and ground. It's been a while since I built a coupler, but 
I built it into a junction box with a three-prong plug coming out through a wire 
clamp and with a BNC on the faceplate. I know I could get down to around 500 kHz 
or so without trouble. Seems like the capacitor was a few picofarad rated at 
something like a thousand volts and the drain coil was a dozen or so turns 
around some torroid core I had laying around.

It's something you need to take serious as you do it, but as long as you do the 
math (calculate the impedance of the capacitor and the coil at both 60Hz and at 
the RF range you are interested in) it is reasonably safe. Measure to make sure 
there aren't any strange things going on before you hook your receiver up.

You can also look at some of the old "carrier" systems that were designed to 
pipe music around the house over the wiring. They were popular in the 1960s or 
so. Their schematics would show you a sample coupling scheme. I suspect if you 
google "x10 coupling" you'll also find some examples.
 73 de
Jim W4JBM 

http://www.hamuniverse.com/w4jbm/

"With a soldering iron in one hand, a schematic in the other, and a puzzled look 
on his face..." 




----- Original Message ----
From: KD7JYK DM09 <kd7jyk at earthlink.net>
To: "Discussion of the Lowfer (US, European, &amp; UK) and MedFer bands" 
<lowfer at mailman.qth.net>
Sent: Wed, February 29, 2012 4:50:17 PM
Subject: [Lowfer] Hz question.

I have an idea, want to run part of it by the LF guys.

I have a single wire, part of a 3-wire 60 Hz 120VAC system.  I want to 
monitor any RFI there may be on the wire in a very simple fashion.  I figure 
a could "sample" it by running the AC wire through a torroid, possibly a 
ferrite tube, possibly a binocular torroid, then wrap a few turns of a 
sampling wire through the torroid as well, then tap into this secondary for 
analysis.

Comments or suggestions?

Kurt

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