% Reduction - AM reception range - increased noise - 1920 to 2024

[Robert Douglas]

An additional factor of the increase in the noise level of the AM broadcast band is the increase of the power line distribution voltage. For many years the distribution voltage to residential neighborhoods was 2,300 or 4,160 volts. In the ‘70’s and 80’s the distribution voltages rose in many areas to 13,800 volts which caused additional noise from corona discharge and arcing issues from dirty or defective insulators. All of this was was in an effort to reduce “copper” losses due to the fact that the efficiency of the distribution system for a given wire size is dependent on the current. More recently, some systems are using 35,000 volts to distribute electricity in residential areas. Needless to say, this has only caused more noise issues for the AM broadcast band.

That explains so much, thanks! I divide my time between two cities, one has that horrible noise on the AM band, and another is quiet. The stuff inside the home, except for a dimmer switch, or maybe putting a radio next to the refrigerator, has very little effect. Both cities have nasty noise on the FM band from the tv/internet cable systems.

 

[cc333]

The AM band at the new house I'm moving to is decently clean compared to the one I'm leaving, at least outside.

AM radios inside the house are virtually useless. Noting but electrical noise and static across the whole band. Even FM is affected somewhat.

It's a relatively modern house (built in 2000), which must be a factor?

It's rather disappointing, to say the least.

c

 

[Weiserguy]

The AM band at the new house I'm moving to is decently clean compared to the one I'm leaving, at least outside.

AM radios inside the house are virtually useless. Noting but electrical noise and static across the whole band. Even FM is affected somewhat.

It's a relatively modern house (built in 2000), which must be a factor?

It's rather disappointing, to say the least.

c

If you want to try isolating the problem before you move in, bring a battery-operated AM (or AM-FM) radio over there and find local stations with strong-but-noisy signal. Then kill the master circuit breaker to the house. Knock out LED lighting, CFL's, fluorescent ballasts, dimmer switches, computers (including laptops and other battery-powered devices), routers, etc. Even TV's and more recent-vintage appliances. Then check your AM radio again. Is the noise still there or has it largely cleared up? Dial around, check other stations..

If the RF noise has decreased significantly, you have RFI generators inside the house and you should try to locate them. If the noise is mostly the same, it's in the environment external to the house. (It could be coming from a neighbor's house, a commercial or industrial site nearby, or even the power line itself. Some power companies transmit broadband data over their power lines and/or control telemetry.) If the problem's inside your house and the AM gets a clean signal from nearby stations, flip the master breaker back on and wander around the house with the AM radio. The noise will get appreciably louder when you're nearby a noise generator, and you can test by turning that device or switch on and off to see if the buzzing comes and goes. Pay extra attention to anything on a dimmer, including wall switches or lights with built-in dimmers. (I've installed dimmer switches in place of old-fashioned On-Off switches, and the radius around those switches becomes unlistenable any time they're turned on.)

Hope that helps a little.