Noise. Unsure if it's power line. This is in an area I could hear the station on 1700.
Power line noise. Same as what you hear in homes and buildings. Dirty electricity radiating noise. Remember back before the 80s AM used to be clean with none of that. The power grid didn't have all this crap on it. To prove it if the power went out that would be gone.
@mark I don't have that in my house. Could be the old transformers that's been in used for decades.
@wefr You are lucky! LED TVs, coffee makers, not even turned on and just plugged in is making noise from RF radiation. Dimmer switches, chargers, computers, smartphones, night lights, CFL bulbs and LED bulbs, routers, all from millions of homes and buildings dirty the power grid and kill AM radio. Even if you are in the cabin in the country you have the wiring around you radiating the dirty power from hundreds of miles away. With our hobby and small signals the AM signal has to get through all of this. You may get a mile reception outside but not in homes or buildings. I myself am guilty. The TV is never watched but plugged in. I have a power station as a UPS for my station and that causes noise. I have a computer and even when turned off and "sleeping" still causes noise. The computer for my station is on 24/7. Everyone with these phones on all the time are AM noise killers. 200 million people charging them at the same time is making dirty electricity all over the country! Unfortunately we have all killed AM radio reception. And as you tune to different frequencies the noise sounds different.
Here's a couple of videos of interest.
Actually I do have some noise from LED bulbs right when they ready to die. Low frequency hum from them. That and cheap receivers don't help. Radios aren't built like they was back in the day. Warmer weather in spring and summer time adds to it.
Mark mentioned "Everyone with these phones on all the time are AM noise killers. -
I get your overall point, but I dont think our cellphones even at near field interfere with AM reception. You can set your cellphone next to or on top of an AM radio and not hear any interference at all?
Never had the phone to do it, but sometimes a charger that's poorly made will do it.
@richpowers Watch one of the videos I posted that shows an AM radio and the phone near it. Emits the same as an LCD/LED TV or a computer. More importantly it's what all this stuff causes on the AC power grid. Before the 1980s you had relatively clean 60Hz AC power. You could have your tube AM radio operating on AC power and it was clean.
I have yet to find a phone charger (cheap or otherwise) that didn't induce hum and noise into my AM signal. I had to locate the chargers on a different AC circuit, and have it at least 6 feet away from the transmitter.
Interestingly enough, my wifi router is inches away from that same AM transmitter, as well as the FM transmitter, and doesn't interfere at all.
Cell phones will (over-the-air, anyway), depending on the frequency band they operate on. You've got to be pretty close to them to notice it, though (i.e., have the phone placed on the top of the transmitter).