On May 9, 7:33 pm, wrote:
I hate switch mode power supplies.
I hate wall warts.
And I really really hate switch mode wall wart power supplies.
Linear wall warts are bad enough.

Found this while looking for a better (as in active) RFI probe.
http://www.arrl.org/tis/info/cable-modems.html

Switching-type AC adapters are indeed a disaster, at least as far as
shortwave (or MW) radios go.

But a good regulated and filtered "wall-wart" AC adapter has an
advantage over an internal power supply that is little noted: as the
voltage supplied to the radio by the adapter is very low, the owner
can work on the inside of the radio while the radio is operating with
no danger of a high voltage shock.

There are pros and cons to everything.

Best,

Joe

On May 11, 5:50 pm, RHF wrote:
On May 11, 4:12 am, wrote:





On May 11, 2:08 am, RHF wrote:

On May 10, 7:39 pm, Joe Analssandrini
wrote:

On May 9, 7:33 pm, wrote:

I hate switch mode power supplies.
I hate wall warts.
And I really really hate switch mode wall wart power supplies.
Linear wall warts are bad enough.

Found this while looking for a better (as in active) RFI probe.
http://www.arrl.org/tis/info/cable-modems.html

Switching-type AC adapters are indeed a disaster, at least as far as
shortwave (or MW) radios go.

But a good regulated and filtered "wall-wart" AC adapter has an
advantage over an internal power supply that is little noted: as the
voltage supplied to the radio by the adapter is very low, the owner
can work on the inside of the radio while the radio is operating with
no danger of a high voltage shock.

There are pros and cons to everything.

Best,

Joe

IF - The Plug-in-the-Wall AC-to-DC Adaptor that has
the Wall Wart setting directly on the AC Outlet : Then
I also use a "Donut" Shaped Ceramic Magnet on the
DC [Output] Cord about 6" from the DC Power Plug.
NOTE - These Donut Magnets can be bought at RadioShack
and 'look like' a 1"x1/2"x1/4" Ferrite Toroidal Core; but
they are Ceramic Magnets. aka: Refrigerator Magnets
Usually 4-6 Turns through the Hole and around the Magnet
eliminates most RFI coming into the Radio.

IF the AC-to-DC Adaptor has a Power Cord between it
and the AC Outlet : Then I also use a Clamp-On Ferrite
Cores on the AC [Input] Power Cords about 6" from the
AC Power Plug.

I recommend 'trying' both of these first before
"Cracking Open" the AC-to-DC Adaptor. ~ RHF

The other option is using Rechargeable Batteries when
On-the-Radio -and- an Off-Line Charging when not in use.
.
.
. .

A good way to test the wall wart in question if to operate your radio
from the wall wart,
tune down to the MW(AM BCB) and run the lead from the wall wart
across the loop
antenna. If the noise goes up, or MW signals have a "hum" on "top" of
them, or if you
hear mix products, then the supply needs treatment. You can repeat the
test after
each treatment step. Exernal ferrite is the logical first step.

Unless you live pretty close to a broadcaster, cross modulation is not
likely to be an
isue. I live within 4 miles of two MW stations. One is on 770, the
other is 1240.
So I find garbage on 770+1240, and 1240-770. These are out of the MW
band, so
I have to tune to the LW or SW bands.

Some wall warts that are the same model number have very different RFI
charactoristics.
I went to the local Good Will store and built up a supply of RF quite
supplies over a couple
of months. While I hate the d@#^ things, I accept that they are very
useful at times.

When ever possible I operate everything from my Lambda 12V power
supply that have
been treated to kill all RF noise. But there are few devices in our
home that have their
own wall warts. The telephone answering machine wall wart was about
the worst RFI
noise source I have personally experienced. It is a 9V AC so just
substituted the wall
wart that we used with an external 56K modem. Someday when I have the
time I intend
to crack the case and see just what is inside this beast.

Another trick that can be useful is to find a MOV spike protector that
you can open.
I like the GE units, and add a 0.01uF across hot to neutral and hot to
ground. This is
easier then added the capacitors to the home AC outlet.

- I have mentioned the Curtis F1600CA03 3 Amp line filter
- before. These units are only $0.35 each and can do an
- amazing job of killing RFI at the source.
- http://www.hosfelt.com/en-us/dept_572.html
-
- Terry

Terry - Thank You for the TIP ~ RHF

On the CURTIS F1600CA03 3 Amp AC Line Filterhttp://www.hosfelt.com/media/27-120.jpg
and at $0.35 a piece it is a real bargain.
P/N 27-120 = http://www.hosfelt.com/en-us/dept_572.html
.
.
. .- Hide quoted text -

- Show quoted text -

Lots of good emi tips here. I am switchmode power supply engineer and
make a decent living with smps so I like them! They can actually be
integrated into sensitive receiving gear and be very quiet if done
correctly.

NEO

PS I hate them too at home when I am swl. They drive me crazy.

On May 11, 9:02 pm, N9NEO wrote:
On May 11, 5:50 pm, RHF wrote:



On May 11, 4:12 am, wrote:

On May 11, 2:08 am, RHF wrote:

On May 10, 7:39 pm, Joe Analssandrini
wrote:

On May 9, 7:33 pm, wrote:

I hate switch mode power supplies.
I hate wall warts.
And I really really hate switch mode wall wart power supplies.
Linear wall warts are bad enough.

Found this while looking for a better (as in active) RFI probe.
http://www.arrl.org/tis/info/cable-modems.html

Switching-type AC adapters are indeed a disaster, at least as far as
shortwave (or MW) radios go.

But a good regulated and filtered "wall-wart" AC adapter has an
advantage over an internal power supply that is little noted: as the
voltage supplied to the radio by the adapter is very low, the owner
can work on the inside of the radio while the radio is operating with
no danger of a high voltage shock.

There are pros and cons to everything.

Best,

Joe

IF - The Plug-in-the-Wall AC-to-DC Adaptor that has
the Wall Wart setting directly on the AC Outlet : Then
I also use a "Donut" Shaped Ceramic Magnet on the
DC [Output] Cord about 6" from the DC Power Plug.
NOTE - These Donut Magnets can be bought at RadioShack
and 'look like' a 1"x1/2"x1/4" Ferrite Toroidal Core; but
they are Ceramic Magnets. aka: Refrigerator Magnets
Usually 4-6 Turns through the Hole and around the Magnet
eliminates most RFI coming into the Radio.

IF the AC-to-DC Adaptor has a Power Cord between it
and the AC Outlet : Then I also use a Clamp-On Ferrite
Cores on the AC [Input] Power Cords about 6" from the
AC Power Plug.

I recommend 'trying' both of these first before
"Cracking Open" the AC-to-DC Adaptor. ~ RHF

The other option is using Rechargeable Batteries when
On-the-Radio -and- an Off-Line Charging when not in use.
.
.
. .

A good way to test the wall wart in question if to operate your radio
from the wall wart,
tune down to the MW(AM BCB) and run the lead from the wall wart
across the loop
antenna. If the noise goes up, or MW signals have a "hum" on "top" of
them, or if you
hear mix products, then the supply needs treatment. You can repeat the
test after
each treatment step. Exernal ferrite is the logical first step.

Unless you live pretty close to a broadcaster, cross modulation is not
likely to be an
isue. I live within 4 miles of two MW stations. One is on 770, the
other is 1240.
So I find garbage on 770+1240, and 1240-770. These are out of the MW
band, so
I have to tune to the LW or SW bands.

Some wall warts that are the same model number have very different RFI
charactoristics.
I went to the local Good Will store and built up a supply of RF quite
supplies over a couple
of months. While I hate the d@#^ things, I accept that they are very
useful at times.

When ever possible I operate everything from my Lambda 12V power
supply that have
been treated to kill all RF noise. But there are few devices in our
home that have their
own wall warts. The telephone answering machine wall wart was about
the worst RFI
noise source I have personally experienced. It is a 9V AC so just
substituted the wall
wart that we used with an external 56K modem. Someday when I have the
time I intend
to crack the case and see just what is inside this beast.

Another trick that can be useful is to find a MOV spike protector that
you can open.
I like the GE units, and add a 0.01uF across hot to neutral and hot to
ground. This is
easier then added the capacitors to the home AC outlet.

- I have mentioned the Curtis F1600CA03 3 Amp line filter
- before. These units are only $0.35 each and can do an
- amazing job of killing RFI at the source.
- http://www.hosfelt.com/en-us/dept_572.html
-
- Terry

Terry - Thank You for the TIP ~ RHF

On the CURTIS F1600CA03 3 Amp AC Line Filterhttp://www.hosfelt.com/media/27-120.jpg
and at $0.35 a piece it is a real bargain.
P/N 27-120 = http://www.hosfelt.com/en-us/dept_572.html
.
.
. .- Hide quoted text -

- Show quoted text -

Lots of good emi tips here. I am switchmode power supply engineer and
make a decent living with smps so I like them! They can actually be
integrated into sensitive receiving gear and be very quiet if done
correctly.

NEO

PS I hate them too at home when I am swl. They drive me crazy.

You can get shielded inductors and transformers for SMPS, as long as
the bean counters don't get involved. ;-)

Isn't the cheaper solution just to use a fixed frequency in the SMPS,
and pick it so it doesn't effect YOUR product. [Of course, it can
radiate and screw up some other radio. ]

On May 11, 9:02 pm, N9NEO wrote:
On May 11, 5:50 pm, RHF wrote:





On May 11, 4:12 am, wrote:

On May 11, 2:08 am, RHF wrote:

On May 10, 7:39 pm, Joe Analssandrini
wrote:

On May 9, 7:33 pm, wrote:

I hate switch mode power supplies.
I hate wall warts.
And I really really hate switch mode wall wart power supplies.
Linear wall warts are bad enough.

Found this while looking for a better (as in active) RFI probe.
http://www.arrl.org/tis/info/cable-modems.html

Switching-type AC adapters are indeed a disaster, at least as far as
shortwave (or MW) radios go.

But a good regulated and filtered "wall-wart" AC adapter has an
advantage over an internal power supply that is little noted: as the
voltage supplied to the radio by the adapter is very low, the owner
can work on the inside of the radio while the radio is operating with
no danger of a high voltage shock.

There are pros and cons to everything.

Best,

Joe

IF - The Plug-in-the-Wall AC-to-DC Adaptor that has
the Wall Wart setting directly on the AC Outlet : Then
I also use a "Donut" Shaped Ceramic Magnet on the
DC [Output] Cord about 6" from the DC Power Plug.
NOTE - These Donut Magnets can be bought at RadioShack
and 'look like' a 1"x1/2"x1/4" Ferrite Toroidal Core; but
they are Ceramic Magnets. aka: Refrigerator Magnets
Usually 4-6 Turns through the Hole and around the Magnet
eliminates most RFI coming into the Radio.

IF the AC-to-DC Adaptor has a Power Cord between it
and the AC Outlet : Then I also use a Clamp-On Ferrite
Cores on the AC [Input] Power Cords about 6" from the
AC Power Plug.

I recommend 'trying' both of these first before
"Cracking Open" the AC-to-DC Adaptor. ~ RHF

The other option is using Rechargeable Batteries when
On-the-Radio -and- an Off-Line Charging when not in use.
.
.
. .

A good way to test the wall wart in question if to operate your radio
from the wall wart,
tune down to the MW(AM BCB) and run the lead from the wall wart
across the loop
antenna. If the noise goes up, or MW signals have a "hum" on "top" of
them, or if you
hear mix products, then the supply needs treatment. You can repeat the
test after
each treatment step. Exernal ferrite is the logical first step.

Unless you live pretty close to a broadcaster, cross modulation is not
likely to be an
isue. I live within 4 miles of two MW stations. One is on 770, the
other is 1240.
So I find garbage on 770+1240, and 1240-770. These are out of the MW
band, so
I have to tune to the LW or SW bands.

Some wall warts that are the same model number have very different RFI
charactoristics.
I went to the local Good Will store and built up a supply of RF quite
supplies over a couple
of months. While I hate the d@#^ things, I accept that they are very
useful at times.

When ever possible I operate everything from my Lambda 12V power
supply that have
been treated to kill all RF noise. But there are few devices in our
home that have their
own wall warts. The telephone answering machine wall wart was about
the worst RFI
noise source I have personally experienced. It is a 9V AC so just
substituted the wall
wart that we used with an external 56K modem. Someday when I have the
time I intend
to crack the case and see just what is inside this beast.

Another trick that can be useful is to find a MOV spike protector that
you can open.
I like the GE units, and add a 0.01uF across hot to neutral and hot to
ground. This is
easier then added the capacitors to the home AC outlet.

- I have mentioned the Curtis F1600CA03 3 Amp line filter
- before. These units are only $0.35 each and can do an
- amazing job of killing RFI at the source.
- http://www.hosfelt.com/en-us/dept_572.html
-
- Terry

Terry - Thank You for the TIP ~ RHF

On the CURTIS F1600CA03 3 Amp AC Line Filterhttp://www.hosfelt.com/media/27-120.jpg
and at $0.35 a piece it is a real bargain.
P/N 27-120 = http://www.hosfelt.com/en-us/dept_572.html
.
.
. .- Hide quoted text -

- Show quoted text -

Lots of good emi tips here. I am switchmode power supply engineer and
make a decent living with smps so I like them! They can actually be
integrated into sensitive receiving gear and be very quiet if done
correctly.

NEO

PS I hate them too at home when I am swl. They drive me crazy.- Hide quoted text -

- Show quoted text -

'smps' = "SMPS" =Switched-Mode Power Supply(s)
http://en.wikipedia.org/wiki/Switched-mode_power_supply
http://www.smps.us/
http://www.powersupplies.net/
http://www.smpstech.com/
http://www.smps.com/