[600MRG] Noise on 600M

[James Hollander]

Merv-- A similar type interference here comes from some screw-in fluorescent light bulbs, and is verified by turning each bulb off while the 630m receiver is on.  Some of these light bulbs have a few turns of 1/4" glass tube exposed, and other such bulbs have a frosted outer bulb surrounding the turns of glass.

The interference from each such fluorescent light bulb has perhaps twelve tones with 120Hz tone spacing across a 1.5 KHz bandwidth. The whole 1.5KHz ensemble migrates across the 630m band at about 100Hz per minute toward increasing frequencies and then may migrate back down in frequency again sometime later.  In the 630m receiver set for 2.2KHz bandwidth I hear a buzz mixed with a machine-like whirring sound. 

The frequency migration is roughly the rate you describe (or slower) and repeats. The bulbs do this independently of each other and send interference any time of day or night when they have been turned on.  The interference extends at least 100 feet and might be coming from the property where you are or from a near neighbor's property. Sometimes just finding where these bulbs are located can be a challenge when you think all such bulbs are turned off and another such bulb is still left on.  Possibly you have some other mystery interference that also fits your description.  I'd be interested in whatever you learn.     --    73,  Jim H  W5EST