[Hallicrafters] I bet you knew this already.

[Art Lebermann]

Jack....

The simple answer is "no" - you can't filter the noise.  Incandescent lamps are the only ones that are noise-free, as they operate by passing current through a wire.  All other types have some potential to create RF interference.  Some are worse than others.  I'm an engineer for two AM radio stations - one 50 Kw. and one 5 Kw.  I find that I'm answering more calls from our listeners who are complaining about interference to their AM radio reception.  In many cases, the problem is flourescent lamps.  Dimmers on incandescent lamps are also a major problem.  With the push for "energy conservation", this will only get worse.

Art Lebermann, W6REQ
Transmitter Supervisor
KGO and KSFO
San Francisco


----- Original Message ----- 
From: Jack Dunigan 
To: hallicrafters at mailman.qth.net
Sent: 12/8/2008 4:27:43 PM 
Subject: [Hallicrafters] I bet you knew this already.


My radio bench has one of those magnifying lights in which I put one of those curly, energy saver bulbs. It is bright, runs cool, and supposedly saves money. When I fire up my Hallicrafters S38-C and turn on the light, a terrible buzz obliterates all signals on the lower half of the broadcast band. From about 900 khz down absolutely nothing gets through. When I switch off the light, the radio works normally. You all probably knew this already, but I was preparing to tear down the radio, replace filters, change tubes, and the like. Glad I switched off the light. Then I discovered that the radio is affected the same way by another lamp in the room maybe 6 or 7 feet away with a tubular quartz bulb and a dimmer switch. Changing the dimmer changes the tone and intensity of the interference. 

Is there an easy way to filter this out? Incandescent lamps in a ceiling fixture seem to have no effect at all.

Jack
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