AM Radio =-interference- Is there a plug-in or easy filter

** Still working ??

** The usual cause is AC supply frequency modulation of AM radio signals arriving on power wiring in the premises. ** CFLs nearly all have a 100nF or 220nF capacitor that connects directly across the incoming AC wires. These reduce any AM band signals to a much lower level and so avoid the aforementioned supply frequency modulation. ** Doubt it.

** A 1uF, 275VAC cap is all you need.

Wired into the back of a regular AC plug.

... Phil

Thnks Phil. does that cap go in series with one lead of an ACPlug, or across thepower line.

"mike"

** Worth a try - if it will fit. ** My post specified a 275VAC cap ( aka class X1 or X2 suppression caps) .

These are specially would to avoid internal corona that destroys ordinary film caps wired across the AC line.

If you cannot get any, try two 600V film caps in series - that ought to work OK too.

.... Phil

Not if the window glass is "Low-E" and the walls are stucco. Such dwellings are almost a Faraday cage. I live in one. Most of my AM reception is of RF trash generated _inside_ the house.

I found this idea on a web page from a company that makes small high gain antennas for shortwave listening.

Take a portable radio and find the end of the "noise cloud" around your home an put an antenna there. Of course if you are in a tight urban area, or an apartment, you may never find it. :-(

Geoff.

--
Geoffrey S. Mendelson,  N3OWJ/4X1GM/KBUH7245/KBUW5379

I remember forty years ago I could just stick a few feet of wire on the SP-600 and reception was fine. Now, there is so much noise from all the electronic junk that didn't exist back then, that you really need the antenna outside, or at the very least, next to the window. The signals suddenly leap out, but it's a combination of stronger signals from outside, and weaker signals from inside.

Michael

However when I turn ON various CFL light fixtures around the house, the hum disappears.

Leave the light on! Put a shade on it? Paint it black?

electronic junk that didn't exist back then..."

That's what I'm talking about. These days if it ain't Ghz there is all kind of noise all over the place. Sure there is some on the power lines etc., b ut it is also in the air.

Just for a test, if anyone is so inclined, just take a scope probe and conn ect it to a big piece of metal. You are going to see more shit there than.. . well, I lack a proper metaphor at this moment. Sorry. But there is alot. Sometimes I'm surprised anything works.

Back many years ago, I had a shop scope that picked up a 1430 khz modulated signal clean as could be. Mikek

** Folk living in mobile or re-locatable homes with * metal * walls have a bit of a problem with AM radio too...

.... Phil

I have such a triple-wide home. Aluminum siding all around. Fortunately, the roof is not metal, so the little RF'ies can get in there! My pole shop/garage is worse. Has 4 metal walls, plus metal roof.

Paul

The first question I would ask is, "What's your antenna setup?"

For TV, and for FM radio, the most important aspect to getting good signal quality is having a good antenna arrangement - a proper antenna mounted where it can "see" the transmitters with a minimum of interfering solid matter between the two.

Indoor antennas - "rabbit ears", floppy dipoles, and small wall-mount panel antennas - are usually suitable only for "strong signal" areas fairly close to the transmitters. Modern buildings are often quite effective shields against RF transmission - they contain materials which either absorb or reflect RF - steel beams, wire mesh in stucco walls, metallized plastic insulation and vapor barriers, and so forth. Signals from distant stations don't stand a chance... they're weakened, and also degraded by multipath (multiple RF paths of different lengths, caused by signal reflections, which result in frequency-selective signal reinforcement and cancellation).

The results of all of this are bad signals. Analog TV suffers from noise and "ghosts". FM suffers from noise and distortion. Digital TV suffers from pixellation, freezing, and "no signal found" problems.

These problems can all be made worse by local interference, radiated or conducted. They're also made worse by short-term multipath - e.g. signal reflections from airplanes flying within the line-of-sight, or even trucks driving by on the road outside. On FM you can hear a "picket fencing" effect when this happens, on analog TV you see moving "ghosts", and on digital TV you see pixellation and freezing. Digital TV receivers do have the ability to detect and cancel out some multipath reflections, but dealing with rapidly changing reflections is a "hard problem" for them and they often don't adapt fast enough.

Filters at the receiving end (TV, FM radio) won't help, except in the case where the TV is picking up _conducted_ RF interference through the power line. Can't hurt to try, but don't expect miracles.

Filters at the sources of interference (noisy motors, PC power supplies, LED lights, light dimmers) may help somewhat. However, even if you completely filter all local noise sources, there can still be plenty of noise from outside the house/apartment - neighbors' equipment, etc.

The real "fix" is to improve the quality of the incoming RF signal... you want a strong signal with minimal multipath. This often requires an outdoor antenna - one mounted up "in the clear" (e.g. on a roof mast). If possible, install a directional antenna which is aimed in the direction of the desired transmitter - this both boosts the amount of "good" signal (thanks to the antenna's gain) and also reduces the amount of "bad" signal (multipath reflections coming in from other directions, and random interference from sources in the area). If necessary, install a remote-controlled antenna rotator, or an electronically-rotatable antenna (if your TV has the ability to control one of these - most do not, I believe).

If you're getting your over-the-air TV signal via a cable-TV feed, and the quality is still poor, then check your coax connections, and/or complain to the cable company.