Topband: A CFL Bulb Issue

Joe Subich, W4TV lists at
Tue Mar 25 14:03:36 EDT 2014

Understand what these compact florescent bulbs really are ... a small,
tightly coiled, florescent tube with an *electronic ballast*.  The
electronic ballast is nothing more than a small, cheap switching power
supply to generate the high voltage necessary to fire the tube.

When a CFL fails it is invariably the electronic ballast that goes -
often breaking down (arcing internally) under the high voltage.

Most of the bulbs these days are quiet in normal operation but once
they start arcing internally - particularly the bypass and filter caps - 
it becomes a small spark transmitter with a very large antenna.


    ... Joe, W4TV

On 3/25/2014 1:37 PM, Steve wrote:
>> these CFL bulbs can generate some strong RF
>> noise just before going out.
> Mack - had a similar issue here several years ago...s9+ buzz throughout
> the longwave band for a month. I live on an island with very few winter
> neighbours and eventually traced the source (which was radiating nicely
> via the powerlines) to an unoccupied summer residence, but still was not
> 100% certain as the signal was so loud from all of the 11 home's drop
> lines on the local grid. When the owner returned I had him pull the main
> breaker and sure enough the buzz stopped. It turned out to be a
> burned-out CFL bulb in the crawlspace that they left on to discourage
> any sea otters from trying to get into the space during the winter. The
> bulb was heavily charred and parts of it had already melted yet it
> continued to radiate a strong signal. Needless to say they were glad
> that it hadn't set their place on fire and have since stopped using this
> type of bulb.
> Steve / VE7SL
> Mayne Island, BC
> WEB - "The VE7SL Radio Notebook":
> _________________
> Topband Reflector Archives -

More information about the Topband mailing list