[RFI] The ARRL Contest Update for April 1, 2020

AA5CT jwin95 at yahoo.com
Wed Apr 1 22:00:34 EDT 2020

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 at gmail.com> wrote:  
 Thanks Ed and others.  Looks like a problem for VHF hams.


Can incandescent light bulbs cause interference? | EMC and Regulatory
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.
RFI mailing list
RFI at contesting.com

More information about the RFI mailing list