Hi

Anyone have any idea what is going on in this scenario:

Kitchen outlets, all on the same circuit breaker all grounded but no GFI
outlets. AM radio plugged into an outlet is producing hum. Maybe what
one would consider to be normal. But...

Turn on a toaster oven plugged into a different outlet in the kitchen
and the hum *goes away.* Completely gone.

Plug a fan into the the "toaster oven outlet" and the hum gets worse.
Fan doesn't have to be turned on - just plugged in - to produce hum on
the radio.

Unplug both the toaster oven and the fan and the hum is back on the
radio. But it sounds worse when the fan is plugged in.

Is this anything to be concerned about? This is an apartment so I would
have to give the owner clear insight into any problem with the wiring,
if this represents something that should be corrected. And this only
started happening in the last couple months. Up to that point - no hum
on the AM radio.

Rick

"Rick" wrote in message ...

Hi

Anyone have any idea what is going on in this scenario:

Kitchen outlets, all on the same circuit breaker all grounded but no GFI
outlets. AM radio plugged into an outlet is producing hum. Maybe what
one would consider to be normal. But...

Turn on a toaster oven plugged into a different outlet in the kitchen
and the hum *goes away.* Completely gone.

Plug a fan into the the "toaster oven outlet" and the hum gets worse.
Fan doesn't have to be turned on - just plugged in - to produce hum on
the radio.

Unplug both the toaster oven and the fan and the hum is back on the
radio. But it sounds worse when the fan is plugged in.

Is this anything to be concerned about? This is an apartment so I would
have to give the owner clear insight into any problem with the wiring,
if this represents something that should be corrected. And this only
started happening in the last couple months. Up to that point - no hum
on the AM radio.

Rick

Not a good sign. What happens to the hum as you move the radio to point in
different compass directions?

N

Or what happens if you move the radio to the same plug as the fan and the
toaster oven? Or just move the radio in the room? Does the hum change?

What about another room/another circuit - same situation? Take both your
radio and your fan.

Just thinking - what would a loose neutral in the breaker box do? Could
there be some kind of ground loop happening that is influenced by slight
capacitance/inductance changes on the loop?

WT

"NSM" wrote in message news:AfFre.55008$HI.9967@edtnps84...

"Rick" wrote in message
...

Hi

Anyone have any idea what is going on in this scenario:

Kitchen outlets, all on the same circuit breaker all grounded but no GFI
outlets. AM radio plugged into an outlet is producing hum. Maybe what
one would consider to be normal. But...

Turn on a toaster oven plugged into a different outlet in the kitchen
and the hum *goes away.* Completely gone.

Plug a fan into the the "toaster oven outlet" and the hum gets worse.
Fan doesn't have to be turned on - just plugged in - to produce hum on
the radio.

Unplug both the toaster oven and the fan and the hum is back on the
radio. But it sounds worse when the fan is plugged in.

Is this anything to be concerned about? This is an apartment so I would
have to give the owner clear insight into any problem with the wiring,
if this represents something that should be corrected. And this only
started happening in the last couple months. Up to that point - no hum
on the AM radio.

Rick

Not a good sign. What happens to the hum as you move the radio to point in
different compass directions?

N

Rick--

Is the door bell stepdown transformer on the same circuit?

Tut

In article , Rick wrote:

Kitchen outlets, all on the same circuit breaker all grounded but no GFI
outlets. AM radio plugged into an outlet is producing hum. Maybe what
one would consider to be normal. But...

Turn on a toaster oven plugged into a different outlet in the kitchen
and the hum *goes away.* Completely gone.

Rick-

Having been raised in an older house without a ground wire connected to
the outlets, I learned early that radio hum can often be cured by
reversing the plug.

More modern equipment has a polarized plug with one blade wider than the
other. The wider blade goes to the neutral wire in the outlet. The
narrow blade goes to the hot wire. If your radio's plug is not polarized,
you may have unplugged it a couple of months ago, and had a 50-50 chance
of plugging it back opposite to the way it was before.

The neutral wire is not exactly the same as a ground wire, although they
might be tied together back at a power pole down the block. The radio may
be picking up some kind of power line hash when its "neutral" wire is
connected to the hot side of the outlet.

I used to use a dot of fingernail polish on the narrow-slot side of an
outlet, with a corresponding dot on the plug of a radio that worked better
plugged-in one way.

Fred

The neutral wire is not exactly the same as a ground wire, although they
might be tied together back at a power pole down the block. The radio may
be picking up some kind of power line hash when its "neutral" wire is
connected to the hot side of the outlet.



They darn well better be tied together in the service panel in the house,
but that's not to say there won't be a slight voltage difference between
them at a receptacle if there's other loads on the line.

cnctut wrote:

Rick--

Is the door bell stepdown transformer on the same circuit?

Tut

No transformer in the apartment wiring. Separate apartment intercom
system, presumably on it's own common area wiring for the building and
completely independing of the apartment wiring.

Rick

Fred McKenzie wrote:

In article , Rick wrote:

Kitchen outlets, all on the same circuit breaker all grounded but no GFI
outlets. AM radio plugged into an outlet is producing hum. Maybe what
one would consider to be normal. But...

Turn on a toaster oven plugged into a different outlet in the kitchen
and the hum *goes away.* Completely gone.

Rick-

Having been raised in an older house without a ground wire connected to
the outlets, I learned early that radio hum can often be cured by
reversing the plug.

More modern equipment has a polarized plug with one blade wider than the
other. The wider blade goes to the neutral wire in the outlet. The
narrow blade goes to the hot wire. If your radio's plug is not polarized,
you may have unplugged it a couple of months ago, and had a 50-50 chance
of plugging it back opposite to the way it was before.

Hi

Of course. That's one of the first things I tried - reversing the radio
plug in the outlet - and the hum went from bad to slightly worse. It's a
transistor boom box thing with an internal power supply - not using an
AC/DC wall wart.

FWIW this is relatively new wiring in the building, circa 1981 the
entire building was gutted and all new services put in.

But this hum problem has only surfaced in the last 8 weeks or so.

The neutral wire is not exactly the same as a ground wire, although they
might be tied together back at a power pole down the block. The radio may
be picking up some kind of power line hash when its "neutral" wire is
connected to the hot side of the outlet.

I used to use a dot of fingernail polish on the narrow-slot side of an
outlet, with a corresponding dot on the plug of a radio that worked better
plugged-in one way.

Fred

Could this be one of those situation where a "plug in the outlet" tester
(about 6 bucks at a hardware store or Radio Schlock) would show anything
relevant?

Rick

NSM wrote:

"Rick" wrote in message ...

Hi

Anyone have any idea what is going on in this scenario:

Kitchen outlets, all on the same circuit breaker all grounded but no GFI
outlets. AM radio plugged into an outlet is producing hum. Maybe what
one would consider to be normal. But...

Turn on a toaster oven plugged into a different outlet in the kitchen
and the hum *goes away.* Completely gone.

Plug a fan into the the "toaster oven outlet" and the hum gets worse.
Fan doesn't have to be turned on - just plugged in - to produce hum on
the radio.

Unplug both the toaster oven and the fan and the hum is back on the
radio. But it sounds worse when the fan is plugged in.

Is this anything to be concerned about? This is an apartment so I would
have to give the owner clear insight into any problem with the wiring,
if this represents something that should be corrected. And this only
started happening in the last couple months. Up to that point - no hum
on the AM radio.

Rick

Not a good sign. What happens to the hum as you move the radio to point in
different compass directions?

N

Hi

Tried that first, thinking the radio - and being AM recption on top of
it - may be having a bad time due to some RF interference it was picking
up. Repositioning the radio has no effect on the hum. Picked it up &
rotated it. Left it on the counter where it's located & rotated it. No
better, no worse.

FWIW this is a *strong* signal from the station I'm tuning with no
reception problems. (50,000 watt station and I'm all of 5 miles away
from the tower) If the station is cleanly tuned in, or you start moving
the tuning off frequency, the hum level doesn't change.

Rick

Wayne Tiffany wrote:

Or what happens if you move the radio to the same plug as the fan and the
toaster oven?

Ok, here we go:

Oh - wait. *Now* I'm back to a phase where the hum problem has simply
disappeared. When it does go away, some times it stays like that for a
day or two. Some times only for a few hours. But I'll report in the
answers to these questions as soon as the problem returns. It always
does.

Or just move the radio in the room? Does the hum change?

What about another room/another circuit - same situation? Take both your
radio and your fan.

Just thinking - what would a loose neutral in the breaker box do? Could
there be some kind of ground loop happening that is influenced by slight
capacitance/inductance changes on the loop?

WT

Another question along this line is: Could this be completely outside
the wiring in the apartment or the building? I know the building is fed
from pole mounted wiring with a pole mounted transformer very close to
where the feed is split out for the building. (About 20 yards down from
the transformer location.)

I'm just trying to figure out if this flaky AM hum problem indicates a
serious wiring problem - like a floating ground - wherever the souce may
be coming from.

Rick


"NSM" wrote in message news:AfFre.55008$HI.9967@edtnps84...

"Rick" wrote in message
...

Hi

Anyone have any idea what is going on in this scenario:

Kitchen outlets, all on the same circuit breaker all grounded but no GFI
outlets. AM radio plugged into an outlet is producing hum. Maybe what
one would consider to be normal. But...

Turn on a toaster oven plugged into a different outlet in the kitchen
and the hum *goes away.* Completely gone.

Plug a fan into the the "toaster oven outlet" and the hum gets worse.
Fan doesn't have to be turned on - just plugged in - to produce hum on
the radio.

Unplug both the toaster oven and the fan and the hum is back on the
radio. But it sounds worse when the fan is plugged in.

Is this anything to be concerned about? This is an apartment so I would
have to give the owner clear insight into any problem with the wiring,
if this represents something that should be corrected. And this only
started happening in the last couple months. Up to that point - no hum
on the AM radio.

Rick

Not a good sign. What happens to the hum as you move the radio to point in
different compass directions?

N

"Rick" wrote in message ...

Could this be one of those situation where a "plug in the outlet" tester
(about 6 bucks at a hardware store or Radio Schlock) would show anything
relevant?

Doubtful.

N

Rick wrote:

snip

Oh - wait. *Now* I'm back to a phase where the hum problem has simply
disappeared. When it does go away, some times it stays like that for a
day or two. Some times only for a few hours. But I'll report in the
answers to these questions as soon as the problem returns. It always
does.


Hi..

Haven't followed the thread, so if I repeat someone else
I apologize...

Wondering if your building might possibly be on one of those
flat rate electric water heating plans? Where the hydro
utility puts a signal on the line to turn off the heaters
during peak demand periods?

If so, then that plus a perhaps marginal electrolytics in
the radio might be an explanation.

Just thinking...

Ken

In article Vwjse.6938$El.2117@pd7tw1no, Ken Weitzel wrote:

Rick wrote:

snip

Wondering if your building might possibly be on one of those
flat rate electric water heating plans? Where the hydro
utility puts a signal on the line to turn off the heaters
during peak demand periods?

If so, then that plus a perhaps marginal electrolytics in
the radio might be an explanation.

Ken & Rick-

Of course it would help if you had laboratory equipment to analyze the
spectrum of the power line signal, as well as to determine how the noise
was getting into the radio.

Something is generating a signal that is somehow coupling into the radio
and coming out the speaker. Ken's idea suggests that it might be getting
into the radio through the power line, but either at the intermediate
frequency of the radio or through the audio section, either directly or
by rectification.

I'm a little skeptical about the radio having faulty electrolytics, but
they could have aged if it is an older radio. I would want to try a line
filter of some kind, just inside the radio. Perhaps as simple as putting
a 0.1 Microfarad 600 volt capacitor across the line, with leads as short
as practical. However, I recall cases where such a filter made things
worse!

Fred

I, too, am skeptical about the electrolytics causing the hum..... if they
were bad I would expect the hum to be there all the time no matter what
other things were switched on and no matter where the radio is plugged in.
Is the hum present on all stations or just a few the local strong
stations???--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


"Fred McKenzie" wrote in message
...
In article Vwjse.6938$El.2117@pd7tw1no, Ken Weitzel
wrote:

Rick wrote:

snip

Wondering if your building might possibly be on one of those
flat rate electric water heating plans? Where the hydro
utility puts a signal on the line to turn off the heaters
during peak demand periods?

If so, then that plus a perhaps marginal electrolytics in
the radio might be an explanation.

Ken & Rick-

Of course it would help if you had laboratory equipment to analyze the
spectrum of the power line signal, as well as to determine how the noise
was getting into the radio.

Something is generating a signal that is somehow coupling into the radio
and coming out the speaker. Ken's idea suggests that it might be getting
into the radio through the power line, but either at the intermediate
frequency of the radio or through the audio section, either directly or
by rectification.

I'm a little skeptical about the radio having faulty electrolytics, but
they could have aged if it is an older radio. I would want to try a line
filter of some kind, just inside the radio. Perhaps as simple as putting
a 0.1 Microfarad 600 volt capacitor across the line, with leads as short
as practical. However, I recall cases where such a filter made things
worse!

Fred

You might want to shut off the breaker and check for a loose
connection on the AC power outlets in the kitchen. You may want to
replace them if the they don't hold the plug tightly. They should be
less than a $1 each. Figure they were last served in '81 - that's 24
years ago.

Also, if your boombox has batteries install, you may want to remove
them if you're only using it on AC.

"sssayers" wrote in message
...
You might want to shut off the breaker and check for a loose
connection on the AC power outlets in the kitchen. You may want to
replace them if the they don't hold the plug tightly. They should be
less than a $1 each. Figure they were last served in '81 - that's 24
years ago.

Also, if your boombox has batteries install, you may want to remove
them if you're only using it on AC.


Don't get the cheap under $1 outlets, at least go for the decent grade
stuff, they're only about $1.50 and will last much longer. I found the cheap
ones get loose after a couple years.

Also use the screw terminals or clamp type backwire terminals, don't use the
cheap push-in backwire, they get loose after time and can heat up, they
ought to be agaist code but the unions wouldn't let that happen, saves too
much time installing.

In article , Rick wrote:
Of course. That's one of the first things I tried - reversing the radio
plug in the outlet - and the hum went from bad to slightly worse. It's a
transistor boom box thing with an internal power supply - not using an
AC/DC wall wart.

FWIW this is relatively new wiring in the building, circa 1981 the
entire building was gutted and all new services put in.

But this hum problem has only surfaced in the last 8 weeks or so.

1. Make sure the station (or an adjacent one) hasn't changed to IBOC/(HD
Radio), This is where they add a bunch of digital crap to the channel
that's a high compression digital (RealAudio style) stereo signal.
One test is that they don't run IBOC during the night because the skip
signals will really screw up the radio all over the continent.

2. It might be another device on the circuit with a tranformerless
power supply where the diodes in the power supply hooked right to
the power line switching on and off modulate any radio signals
picked up on power line.

Mark Zenier Washington State resident

Rick wrote in :

Hi

Anyone have any idea what is going on in this scenario:

Kitchen outlets, all on the same circuit breaker all grounded but no GFI
outlets. AM radio plugged into an outlet is producing hum. Maybe what
one would consider to be normal. But...

Turn on a toaster oven plugged into a different outlet in the kitchen
and the hum *goes away.* Completely gone.

Plug a fan into the the "toaster oven outlet" and the hum gets worse.
Fan doesn't have to be turned on - just plugged in - to produce hum on
the radio.

Unplug both the toaster oven and the fan and the hum is back on the
radio. But it sounds worse when the fan is plugged in.

Is this anything to be concerned about? This is an apartment so I would
have to give the owner clear insight into any problem with the wiring,
if this represents something that should be corrected. And this only
started happening in the last couple months. Up to that point - no hum
on the AM radio.

Rick

One question that no one else seems to have asked:
is the loudness of the hum changed by the volume control?
Specifically, does the hum stay the same level and only the
radio signal changes in volume as you adjust the volume control?
Or does the hum also go down as the volume control is turned down?

Rick
(different one)