Fortunately, those are not the lamp style the German researchers found
troublesome.
An up and down filament does not compare to the many up and down filament of
the bulbs that interfered.
Also, a key to this is the 'problem' lamps have a parallel resonance in the
bands they
oscillate in. Below is the finding of one researcher:
o Resonance properties of the lamps
The resonance properties of the lamps were determined with the aid of a vector
impedance meter (HP). The following values resulted, with the measurements
carried out when cold. The measurement was performed directly on the lamp base:
40W lamp: Parallel resonance at approximately 60MHz, ± 45 deg Z bandwidth: 10
MHz
60W lamp: Parallel resonance at approximately 70MHz, ± 45 deg Z range: about 8
MHz
The lamps have Fo (in the cold state) resonance properties that can later be
found (seen) in the (active oscillating) spectrum measurements (observations).
-------------------
So there is a clue. The internal lamp structures offer supporting 'resonance'
and very little
dependence on the feeding via the lamp cord or external loading (series) coils.
de AA5CT Jim
.
.
On Wednesday, April 1, 2020, 08:41:58 PM GMT-5, Rob Atkinson
<ranchorobbo@gmail.com> wrote:
Thanks Ed and others. Looks like a problem for VHF hams.
https://www.amazon.com/CTKcom-Nostalgic-Tungsten-Incandescent-Industrial/dp/B06XDBDTGN/ref=sr_1_19?qid=1585791373&refinements=p_n_feature_three_browse-bin%3A4906234011&s=hi&sr=1-19
Rob
K5UJ
https://www.emcrules.com/2017/04/can-incandescent-light-bulbs-cau<https://www.emcrules.com/2017/04/can-incandescent-light-bulbs-cause.html>
se.html<https://www.emcrules.com/2017/04/can-incandescent-light-bulbs-cause.html>
[https://4.bp.blogspot.com/-9VvK7nvAz1o/WN2WAbM_aSI/AAAAAAAAAeU/rDw7H-8XND0O8GI9djPNKX2258v62yJ9ACEw/w1200-h630-p-k-no-nu/vintage-2061732_640.jpg]<https://www.emcrules.com/2017/04/can-incandescent-light-bulbs-cause.html>
Can incandescent light bulbs cause interference? | EMC and Regulatory
Compliance<https://www.emcrules.com/2017/04/can-incandescent-light-bulbs-cause.html>
Recently the European market surveillance authorities (AdCos) on EMC have been
investigating the potential of incandescent light bulbs to cause radio
interference. The investigation began with reports that some incandescent
lights may be the cause of reported interference to FM broadcast reception.
www.emcrules.com
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