Printer causes SW interference!
 

When the SW interference got worse today, I walked around the room (to
start out) with my 396 and noted that the hum was so loud next to my
computer that the signal light lit up. I turned off the power supply and
the noise went away. I'm thinking "great, I need to buy ANOTHER surge
protector". But then I played a hunch and started unplugging stuff one
by one to see if it's really the surge strip and when I unplugged my
computer's printer the noise went away. Plug it back in, and the noise
returns. So instead of spending $20 on a surge protector, I'm looking at
$120+ for a new printer. But that's ok since it was acting up in other
ways, for example the paper feed quit working so it wouldn't
automatically feed paper through, I had to feed it each sheet by hand.
It's not always a power line problem, guys. I think the other guy who
was having a hum on the tropical bands should try what I did.

Plug-in surge protectors don't even claim to protect from
the destructive type of surge. Why will it stop a transmitter
inside the computer from transmitting noise? Protector does
not claim to do that either.

You don't yet know what the noise source is. For example,
computer power supplies priced for less than $80 retail are
missing essential functions include EMI/RFI filters. The
solution to noise on power supply cord is a power supply that
meets Intel ATX specifications (which $40 power supplies do
not). That printer cable could simply be an antenna to
transmit motherboard or power supply generated noise.

Better motherboards include filters on that printer port
cable. Just another function often missing on some clone
motherboards.

Your solution is found inside the equipment - and not in
some plug-in component.

tommyknocker wrote:
When the SW interference got worse today, I walked around the room
(to start out) with my 396 and noted that the hum was so loud next
to my computer that the signal light lit up. I turned off the power
supply and the noise went away. I'm thinking "great, I need to buy
ANOTHER surge protector". But then I played a hunch and started
unplugging stuff one by one to see if it's really the surge strip
and when I unplugged my computer's printer the noise went away.
Plug it back in, and the noise returns. So instead of spending $20
on a surge protector, I'm looking at $120+ for a new printer. But
that's ok since it was acting up in other ways, for example the
paper feed quit working so it wouldn't automatically feed paper
through, I had to feed it each sheet by hand. It's not always a
power line problem, guys. I think the other guy who was having a
hum on the tropical bands should try what I did.

In article , tommyknocker
writes:

So instead of spending $20 on a surge protector, I'm looking at
$120+ for a new printer.

remember when they used to cost ~$1,000 ??
just unplug it when your not using it

Hi Tommyknocker.
I have the monitor and PC on a UPS, and the printer, scanner and sound card
are on the surge protector built into the cabinet with the drawer meant for
the monitor to sit on. I also have similar arrangements for the VCR, DVD and
TV, because they all generate RF that interferes. I can't do anything about
RF from other equipment in the vacinity. the monitor is one particular item
that can cause a lot of interference on sw bands, which is why I have it off
of I want to listen.

When we had our recent silver tahw, I think the city turned of the speed
indicators on the two streets near here, becuase the comoputer generated RF
was almost non existant, and it is back again. Of course so many things can
be coincidence, that it is really difficult to know for sure !

Best Wishes.
V
"Diverd4777" wrote in message
...
In article , tommyknocker
writes:

So instead of spending $20 on a surge protector, I'm looking at
$120+ for a new printer.

remember when they used to cost ~$1,000 ??
just unplug it when your not using it

w_tom wrote:

Plug-in surge protectors don't even claim to protect from
the destructive type of surge. Why will it stop a transmitter
inside the computer from transmitting noise? Protector does
not claim to do that either.

Read my posting closer. I didn't say that.

You don't yet know what the noise source is. For example,
computer power supplies priced for less than $80 retail are
missing essential functions include EMI/RFI filters. The
solution to noise on power supply cord is a power supply that
meets Intel ATX specifications (which $40 power supplies do
not). That printer cable could simply be an antenna to
transmit motherboard or power supply generated noise.

Better motherboards include filters on that printer port
cable. Just another function often missing on some clone
motherboards.

Your solution is found inside the equipment - and not in
some plug-in component.

I tried unplugging the computer and turning off the power supply. No
luck. But unplugging the printer worked. My printer is a very low end HP
that has a giant power supply attached to the plug and a wire leading
from the PS to the printer. Note that the problem is NOT the USB cable
connecting the printer to the computer but the printer's power supply.
The power supply to the PRINTER, not the computer.


tommyknocker wrote:
When the SW interference got worse today, I walked around the room
(to start out) with my 396 and noted that the hum was so loud next
to my computer that the signal light lit up. I turned off the power
supply and the noise went away. I'm thinking "great, I need to buy
ANOTHER surge protector". But then I played a hunch and started
unplugging stuff one by one to see if it's really the surge strip
and when I unplugged my computer's printer the noise went away.
Plug it back in, and the noise returns. So instead of spending $20
on a surge protector, I'm looking at $120+ for a new printer. But
that's ok since it was acting up in other ways, for example the
paper feed quit working so it wouldn't automatically feed paper
through, I had to feed it each sheet by hand. It's not always a
power line problem, guys. I think the other guy who was having a
hum on the tropical bands should try what I did.

Monitor cables have a big lump adjacent to the video
controller connector. It is a ferrite filter. You could try
same. Filter would be wrapped by power cord adjacent to where
power cord attaches to printer. Another test would use
braided shield that encases the power cord and attaches (is
grounded) to printer chassis (not to be confused with
printer's electronic ground). These tests to determine source
of noise being from printer electronics.

I hope this is consistent which what you have posted since
the sentences (especially in last paragraph) are not specific
as to which cable is and is not connected when noise is and is
not experienced. IOW if USB cable is or is not connected,
then noise levels do not change?

Warning about measuring noise levels. Sound (amplitude)
from radio does not accurately indicate amount of noise.
Better measurement is to determine distance from 'noise
generator' to get diminished noise. Longer distance means
transmitted noise is greater.

tommyknocker wrote:
I tried unplugging the computer and turning off the power supply. No
luck. But unplugging the printer worked. My printer is a very low
end HP that has a giant power supply attached to the plug and a wire
leading from the PS to the printer. Note that the problem is NOT the
USB cable connecting the printer to the computer but the printer's
power supply. The power supply to the PRINTER, not the computer.