Here's something I never knew before, but I'm sure others have encountered this. I just recapped an RCA R-28-P, got it going and heard some nasty hum. Stations came in loud and clear otherwise. Brand new electrolytics were used, all of sufficient uF values, what could it be? When I went to plug in my signal tracer, I unplugged my little fluorescent gooseneck lamp on the bench and the hum stopped! I'm still looking for tube shields for this one, and there is a really long, unshielded grid wire to the 57 2nd detector sticking out from the rear of the chassis (by design, no less). So I guess the AC from the lamp was getting picked up by the set. Yay, problem solved. Now I have a halogen lamp on the bench with a built-in transformer, no hum problem with it...<P>------------------<BR>

Hi Chuck<P> Noise from fluorescent lamps cause RF interference with radios. <P> What's even stranger light from a fluorescent lamps flicker to the 60 cycle line. If this light shines on tubes it can modulate a signal with 60 cycles. Just blocking the light might eliminate hum?<P>------------------<BR>Norm

If I remember right,there were a few tubes that were quite photosensitive.<BR>Can't remember the tube numbers at the moment, senior moment I guess.<BR> I remember reading an article that used some of these sensitive tubes as photo tubes in a project, as at the time photo tubes were quite expensive.<P>------------------<BR>

I also meant to mention that in the shop I work at, they replaced all the flourescent lights with the "New & Improved energy saving high efficency flourescent lights" with the solid state ballasts.<BR> The new lights totally destroyed any AM & SW reception in the store as well as almost totally blanking out channels 2-6 from the cable co. The SMPS in the ballasts really sucked.<BR> Took us about 6 months to get the landlord & PUD to change the lights back. What a lot of lost time on the bench. <BR>They did try filters but they were only about 50% effective.<P>------------------<BR>

I took the drastic measure of installing incandescent lights close to my fluorscents and use the fluorscents while working at my bench, but use the incandescents when actualy testing/running my radios.<P>------------------<BR>

Right-on Dennis, that's the way i do it!<P>I never know what to expect when I first fire up an old radio under the flourescent fixture over my work bench, sometimes there is a lot of interference and sometimes none! Very often the interference is very strong at the low end of the BC dial and fades out to very little at the high end.<P>I just turn on the track lights for alignment. <P>------------------<BR>

Why can't they make all these danged modern marvels RFI-free so I can SWL in peace? Fluorescent lights, light dimmers -- and worst of all, THIS DANGED COMPUTER, And ATX machines put out the RFI even when off because of the standby supply.<P>Dean<BR><P>------------------<BR>

Good question Dean, you can understand it in the old sets but you would think by now they would have figured it out!<P>------------------<BR>

I was told even hearing aids will pick up that type of noise.<P>------------------<BR>The light of one candle can extinguish all the power of darkness (evil)

I don't know what is going on, but I have a pair of Silencio electronic earmuffs that I wear while shooting and they are great. Only thing is that when I get near the phone line that runs into the range shack, I pick up a buzzing sound in them. Something on the phone line is radiating a buzzy signal and I can pick it up from about six feet away.<BR>Curt<P>------------------<BR>Curt, N7AH

<P>In the telecoil position, I can "hear" the ignition noise that plagues my AM reception in my work van. Can also "hear" the 400 Hz AC in jets...<P>Pete<P><P>------------------<BR>

I've just about completed changing all lights in my home, including the 15 or so tracklights in the shop, over to modern fluorescent equivalents--that was after the last few increases on my electric bill. I was a bit leary, but NO interference noted to date. I still have one dimmer control that raises havoc on the porch lights that needs to be changed, and the computer PS is another issue. <P>Pete<P>------------------<BR>

Another fair source of noise I found is the cell phone charger. I can hear this little bugger in radios the other side of the house from it. This, florescent lites and all other appliances reasonable go off when I'm listening to sw. <P>------------------<BR>

Actually, I don't expect the fluorescent noise problem to get any better. I understand the electronic ballasts will be required by law on all new fixtures and for replacement ballasts since they make the lamps even more efficient than before.<P>Of course, analog TV was supposed to be gone by now, too ....<BR> <BR>Dean<BR><P>------------------<BR>

Hi,<BR> The reason electronic ballasts are so nasty for AM reception is that they step up the line voltage to some 20 odd khz or so, as to eliminate the flicker in the bulbs.<P>Thanks,<BR>Matthew D'Asaro<P>------------------<BR>If it ain't broken, you’re not trying hard enough...