wiedo electrical question and static

After reading lots of wierdo problems here, now I have one that doesn't make sense.
Last night at 2, I was getting static, or the FM version of it (bad reception) on one FM station. A KLH digital clock radio (maybe 150 dollars 24 years ago, with good FM tuning and a rotten AM tuner.)
When I turned on the ceiling light in my bedroom, the rough edges of the sound went away and the sound was clear. When I turned off the light the sound got bad again. Tried it twice. That fixture had one 60 watt incandescent and one 60 watt equivalent cf bulb.
When I turned a lamp with one incancescent bulb, nothing changed.
So I turned that off and turned on -- I don't know the name -- In the 60's they called them high-tension lamps, iirc, that used auto bulbs and had a transformer in the base, that also was heavy enough to keep the lamp from falling over. Now the bulb is a special base and costs about 5 dollars, and has a flat plastic cover over it. When I turned that on, the rough edges went away and the sound was good. Tried it twice.
Then I watched a movie on tv, and tried again at 4AM. That time, the radio workded fine no matter what light was on or off.
I have been having problems with this station for 2 or 3 months, although maybe it is always in the day when the lights are not on.
It's 88.1, a station only 5 to 20 miles from here. OTOH, the other three FM stations have worked well consistently, and they are in DC, 35 to 50 miles from here. 88.1 was fine for years and years and is still fine on all my other radios. Including the 15 dollar clock radio that sits on top of the radio in question, with one 2 inch speaker. Despite how much I paid, KLH doesn't seem to be a very good brand.
Coincidentally?, the incandescent bulb in the ceiling was not working (burnt out? Haven't checked yet) at 4AM, though it never gave a flash of white. But what difference could that make since it when the light is ON that the radio worked well.
The ceiling fixture is on a separate circuit from the radio, along with another ceiling fixture, the attic light, the roof fan, and the outlets at the work bench in the basement.
The other two lamps are plugged into the same outlet as the radio in question. Along with 2 vcr's whose clock was lit but nothing else was running, another clock radio whose time was showing but nothing else was on, and a cradle for a cordless phone charger (that uses a wall wart). A lot of other things are plugged in there, but none were running.
Why doesn't my radio work right when the lights are off?
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mm wrote:

    Did you check to see if the outlets in question were grounded?? That is where I would start.
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Both bulbs were working this morning.

It's behind my bed, but all the outlets in the house are 3 prong. Unless they screwed up this particular outlet, it's grounded. I'll check.
But even if it weren't grounded, how would one account for these symptoms?
And the plug on the radio only has 2 prongs.
And when I woke up this morning, the bad reception was back on that one station, but the reception is good if I turn on the ceiling light or the tensor light.
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<snip>

Try adding a real ground wire to the radio chassis. There may even be a dedicated screw on the chassis for that purpose Connect the other end of the wire to a copper wayer pipe or similar. The result may surprise you. HTH
Joe
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Joe wrote:

Do it with a hot-chassis radio and you'll certainly get a "surprise."
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CJT wrote:

The advice holds though... I have an old Blaupunkt table radio made in the days before grounded outlets. It does indeed have a threaded hole in the chassis intended for a ground connection, and the printing on the pressboard back cover confirms its purpose. Well, I ASSume that that's what the little graphic of a line connected to a spigot means.
nate
(hey, if I have to have a radio, I might as well have a cool looking radio.)
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mm wrote:

You're not going to believe this, but, knowing you, this is a TUBE type radio. No?
Early tube type radios had a set of tubes such that their filament voltage requirements of all the tubes added up to 110volts (a 50, a 35, 3-6s). One side of the incoming power was tied to the chassis and the other went through all the tube filaments in series.
Here's what do: Pull the radio plug out of the wall, turn it 180 degrees, plug it back in. This reverses the hot and neutral in the radio. The chassis will now be at ground potential instead of full power and will shield the interference generated by the rest of the radio's innards.
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wrote:

I have tube radios, but not this one. In my defense, i did say that it was digital and implied it was 24 year old (although I think it is 20.)

I will try this too, although I have to wait until the bad sound comes back.
But my goal isn't so much to fix the problem, now that I have a way around it, but to understand how turning a light on can make interference go away. I know how it could cause interference, but this one stumps me.

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