Am radio Hum

On higher humidity days I get a very loud hum on the bottom end of the am band on the radio in my garage caused by the overhead fluorescent lighting. Is this from the tube or the ballast? On less humid days the hum is still there but not overpowering.

Reply to
Jeff Dieterle
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If you're sure that the hum varies with humidity, you might want to consider the idea that one of the electric utility power company's pole insulators on your street is cracked.

You can sort-of track it down by walking down the street with a portable am radio in hand; the radio should buzz the loudest when you're next to the pole with the faulty insulator.

To get it fixed, call them up and make a complaint, but when will they get around to replacing the insulator is an altogether other matter.

Good Luck!

lighting.

Reply to
Jim Lacko

Hum as opposed to buzz?

Try grounding the fluorescent reflector.

It will probably be a ground problem somewhere in the circuit. Check for an ungrounded outlet nearby. Hard to suggest a specific thing without knowing exactly what the circuit looks like.

You seem to have localized it to the light - turning the light off makes the hum go away . . . Ground the reflector to a known good ground. The light may be the obvious source of the problem but something else may be a contributing factor.

My wife had a turntable that would buzz at the power line frequency. I tried everything I could think of including running a wire to a stake in the ground.

It turned out to be the missing ground on the power transformer supplying the house. I was out mowing the lawn one day and noticed there was no ground on the pole. I worked in power line construction and knew it is required. It looked like someone stole the copper. I called the power company and told them about it - they added a ground at the pole and the turntable buzz problem was fixed.

The ground is required for the lightening arrestors on the transformer to work - there was no argument from the company they just added a ground the next day. Pays to look around the pole now and then - a lightening strike can vaporize the arrestors (a collection of broken porcelain and carbon disks around the base of the pole). Power company will fix that too - and if they don't you can lose every electrical thing in the house and the house . . .

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I like that idea.

He mentions the fluorescent lamp causing the problem so I'm thinking closer to home rather than down the street.

We had a situation like that in a rental house in San Diego - The insulator where the overhead wire came to the house was cracked in half and the wire was resting on the metal lag that screwed into the house.

Seldom rains in SD. But there was a case of "dry" rot around the lag screw. Humidity gets high (another seldom thing) and the wood in the area gets conductive. We did have reception problems - but Radio and TV weren't that important so we didn't try to fix it.

Had a killer rain storm one day . . . I was taking a shower and the water kept getting hotter I kept adjusting it lower. Until I was showering with cold water and getting burned. If I moved further from the shower head - it felt cold - that's when the light bulb went on and I put together the reception problems and the shower. I carefully stepped out of the shower and left it running - wasn't about to touch anything.

Looked outside and the area around the insulator was steaming! Told the building owner about it. He had half the electrical system replaced (that insulator was the only thing not up to code). He raised the rent - we moved.

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Jeff Dieterle

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