----- Original Message -----
From: Alasdair Philips
To: Iris Atzmon
Sent: Thursday, September 02, 2010 9:17 AM
I attach two graphs from
measurements I made comparing various CFLs and an
ordinary incandescent bulb. You may forward them if you
wish. Note they are logarithmic scales - each y-scale
grid line represents a 10-fold increase i.e. 10, 100,
1000, 10000, etc.
Concerned about RF from
Compact Fluorescent Luminaires (CFL bulbs)) we bought a variety of makes and
designs - all labeled 60 watts nominal equivalent light power
compared with conventional incandescent bulbs.
Both graphs and in
decibels (dB). Each y-scale (vertical) interval grid-line
represents a 10-fold different - so a difference in level of 3
lines is a 1000-fold (10*10*10). The bottom reference line
represents the measurements from a conventional incandescent
bulb. All measurements were taken on the same day in the same
experimental setup. It was a metre-cubed earthed and
screened box, with the bulb mounted in the middle of the far
wall and the wide-band antenna mounted in the middle of the
box about 35 cm from the bulb.
The first graph (20-60
kHz) shows the different fundamental driving frequencies of
the different makes. The frequency range is surprising.
All the values were
about 1,000,000 times higher than those at the same
frequencies from the background level which was identical to
the level when the incandescent bulb was used.
The "all to 5 MHz" graph
shows the CFL emissions still at 100 times above background at
2 MHz and 100 times at 5 MHz. So they are a significant RF
polluting source, especially if you sit close to them.