[R-390] Turn off the light !

[Drew P.]

joldenburg2 wrote:

[snipped]

"Had a similar experience this past weekend. Was working on a Hammarlund HQ-120X receiver and had S-8 background noise. I shut off the two tubular fluorescent shop lights in the adjoining room, now S-7. On a whim I cut the shop lights ( it was day time and the bench is in front of a 9-foot window<grin>) and what do you know all the hash was gone. Ends up the compact fluorescent's contain toroid's making for a small noisy switching power supply. Tm to hoard Edison style incandescent for the shop."

Tubular fluorescent lamps can be run on DC to eliminate the noise.  A series limiting resistor is required and does reduce the efficiency, but so run they are still more energy efficient than incandescent. A quick internet search reveals a number of schemes.

Drew