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

[amdx]

On 11/18/2013 12:55 PM, jurb6006@gmail.com wrote:

"Now, there is so much noise from all the
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., but it is also in the air.

Just for a test, if anyone is so inclined, just take a scope probe and connect 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

 

[Phil Allison]

"Allodoxaphobia"

Phil Allison wrote:

They also arrive by penetrating walls and windows without such
modulation.

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.

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



..... Phil

 

[dave]

On 11/18/2013 02:59 AM, jurb6006@gmail.com wrote:

Zanother thing. You think you can prevent a reciever from recieving
that which to it is tuned ? All that fucking noise is right there in
the passband.

I have a device called the MFJ-1026 that does that. It requires a
safecracker's touch and 2 antennas.

 

[Paul Drahn]

On 11/18/2013 2:10 PM, Phil Allison wrote:

"Allodoxaphobia"

Phil Allison wrote:

They also arrive by penetrating walls and windows without such
modulation.

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.


** 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

 

[Peter Jason]

On Sun, 17 Nov 2013 22:45:48 +1100, "Phil Allison"
<phil_a@tpg.com.au> wrote:

michael.muderick@gmail.com

I have a 1970's GE clock transistor radio.

** Still working ??

On AM stations, (1060) there is a lot of buzz/hum.

** The usual cause is AC supply frequency modulation of AM radio signals
arriving on power wiring in the premises.

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

** 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.


Is there a filter commercially available to put on the AC line?

** Doubt it.

Or can I make one?

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

Wired into the back of a regular AC plug.



... Phil

Does this apply to TV interference too? My TV
works only on some channels and the rest show "no
signal" or severe pixellation. Also, the trouble
is intermittent. What can I do? Is there some
sort of filter to fix it?

 

[Look165]

I thought AM was released on the prehistoric era !

Anyway, perturbations might come from AC mains, solar eruption,
neighborhood electric signals, HV lines, AC generator...

To be sure, try to move this AM receiver somewhere else (a friend ?)

Don't forget to check the antenna and/or the orientation of the receiver.

Sometimes, a single 1m wire hanging downward is a good antenna.

Another experiment is to move the receiver near the TV cable
disconnected fromthe TV set.

Since it is an old apparatus, it might be a misalignment of the
receiving part and/or IF section.

A simple cause can also be the loudspeaker (visual check is generally
enough).

If you are lucky, there can be the electric diagram inside.

Peter Jason a Êcrit :

On Sun, 17 Nov 2013 22:45:48 +1100, "Phil Allison"
phil_a@tpg.com.au> wrote:


michael.muderick@gmail.com

I have a 1970's GE clock transistor radio.

** Still working ??

On AM stations, (1060) there is a lot of buzz/hum.

** The usual cause is AC supply frequency modulation of AM radio signals
arriving on power wiring in the premises.

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

** 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.


Is there a filter commercially available to put on the AC line?

** Doubt it.

Or can I make one?

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

Wired into the back of a regular AC plug.



... Phil


Does this apply to TV interference too? My TV
works only on some channels and the rest show "no
signal" or severe pixellation. Also, the trouble
is intermittent. What can I do? Is there some
sort of filter to fix it?

 

[John-Del]

On Monday, November 26, 2018 at 10:33:14 PM UTC-5, Peter Jason wrote:

On Sun, 17 Nov 2013 22:45:48 +1100, "Phil Allison"
phil_a@tpg.com.au> wrote:


michael.muderick@gmail.com

I have a 1970's GE clock transistor radio.

** Still working ??

On AM stations, (1060) there is a lot of buzz/hum.

** The usual cause is AC supply frequency modulation of AM radio signals
arriving on power wiring in the premises.

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

** 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.


Is there a filter commercially available to put on the AC line?

** Doubt it.

Or can I make one?

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

Wired into the back of a regular AC plug.



... Phil


Does this apply to TV interference too? My TV
works only on some channels and the rest show "no
signal" or severe pixellation. Also, the trouble
is intermittent. What can I do? Is there some
sort of filter to fix it?

You don't need a "filter", you need to improve your signal to noise ratio. You need a larger antenna, raise the elevation of the antenna, amplification, or moving nearer to the TV transmitter..

 

[Look165]

No, no relation between AM and TV

For TV check the antenna.

As I said, try it somewhere else.

For the AM receiver, it must be a failure of the AM set (Receiver and
IF section) ; with time (48 years) some inductanes change their value
and condensators too.

John-Del a Êcrit :

On Monday, November 26, 2018 at 10:33:14 PM UTC-5, Peter Jason wrote:
On Sun, 17 Nov 2013 22:45:48 +1100, "Phil Allison"
phil_a@tpg.com.au> wrote:


michael.muderick@gmail.com

I have a 1970's GE clock transistor radio.

** Still working ??

On AM stations, (1060) there is a lot of buzz/hum.

** The usual cause is AC supply frequency modulation of AM radio signals
arriving on power wiring in the premises.

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

** 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.


Is there a filter commercially available to put on the AC line?

** Doubt it.

Or can I make one?

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

Wired into the back of a regular AC plug.



... Phil


Does this apply to TV interference too? My TV
works only on some channels and the rest show "no
signal" or severe pixellation. Also, the trouble
is intermittent. What can I do? Is there some
sort of filter to fix it?



You don't need a "filter", you need to improve your signal to noise ratio. You need a larger antenna, raise the elevation of the antenna, amplification, or moving nearer to the TV transmitter..

 

[Terry Schwartz]

Once again, replying to a 5+ year old post.

 

[Dave Platt]

In article <6kepvd5m3sf4ijcd8ptecr3c2aaunhcm6h@4ax.com>,
Peter Jason <mmmm> wrote:

Does this apply to TV interference too? My TV
works only on some channels and the rest show "no
signal" or severe pixellation. Also, the trouble
is intermittent. What can I do? Is there some
sort of filter to fix it?

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.