Where can I buy a decibel meter in Chicago?

Which tri-field EMF/RF meter shall I buy?

• I want to buy a Tri-field Meter, but there are many to choose from! I was hoping to teach myself and my son about RF and EMF etc... here are the choices: "Fixed" (50hz or 60hz) - my region is 50hz "Flat" "Extended" "Natural" I will tell you my purpose: - i want to measure 'hot spots in my home' from TV's, computers, electrical sockets/wiring, etc. - i ALSO want to go outside and see how pylons and generators and street electrics/motors affect the environment. - ALSO: i wanted to know if there was other sources of EMF or RF that do not come from power-lines that I can measure. - Finally: I want to measure Cell Phones, (but i heard that a trifield meter may not be suitable because it is not so sensitive in the lower areas) - i was told to buy a separate meter for cell phones. so, which device is best for me? and what is the difference between the 4 kinds of meters I listed above? (trifields website does not give any layman comparisons of their meters)

• Answer:

  Had a look at the TF100XE and I'm not exactly impressed. Seems sort of all right on the magnetic fields but the downside is you don't know exactly what you're looking at frequency wise apart from the fact it's within a certain band. There's no detection between 100KHz and 50MHz so that's a bit naff if you were near a high power short wave transmitter for example and the 50MHz-3GHz radio band seems a bit "deaf" i.e. you'd know if the microwave was on in the kitchen but not necessarily if next door's wireless router was working or if they were both on which was which. 50Hz and 60Hz are specifically sensitive to those power frequencies whereas the "flat" version seems to have a restricted frequency response and the "extended" version seems a bit oversensitive and would be of limited value with a frequency response down to 5Hz. Not much works there apart from (maybe) hospital equipment. Before you splash $160 on a TF I'd recommend you get one of the freebie spectrum analyzer programs off the net such as http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=6303 and try audio to start with using a mike then replace the mike with a small audio choke or transformer secondary to check out magnetic stuff. A spectrum analyzer program will show both the frequency and amplitude of what the mic/coil detects. So initially a no cost/low cost way of learning about electromagnetic fields. There are radio versions of spectrum analyzer software packages too.