socraticquest wrote:
>>> On the topic of power supply units. The new power-supply unit produces
>>> interference with AM radio stations. The previous power-supply unit
>>> did not produce radio interference.
>>> What is the advice on power supply units that produce radio
>>> interference?
>>> thanks
>> Switching power supplies do produce harmonics by their very nature, which
>> can extend up into the radio frequency bands, but it sounds like yours isn't
>> as well filtered as the previous one was. Did you change brands?
>>
>
> Yes, the power-supply is a different brand.
Power supplies, have some filter components, just after the
point where the line cord enters the power supply.
There is a schematic of a PC supply here. The components just
before the diode bridge, are there to filter noise. T1, T5,
C4, C2, C3. Some of those components are physically large,
making it a bit easier to spot them inside the power supply.
http://www.pavouk.org/hw/en_atxps.html
Normally, those components would be enough to allow the
supply to meet FCC specifications. The FCC sets rules, for
how much RF interference equipment can produce.
You could try to fix the problem, using a filter like this.
But really, it's not your responsibility, to spend money
to correct a manufacturing defect. And these filters,
actually cost more than your average good quality
ATX power supply! It's much cheaper, if the power supply
manufacturer, puts them inside the supply for you. You would
fit a filter like this, right next to the power supply line
cord input (taking care to build a box to hold this
thing, so no one can touch the AC terminals).
http://cor.com/Series/PowerLine/N/
---> Return the supply and get another one. <---
That's the only way to send the message,
we won't accept crap.
I've had an Antec brand supply do that, and
even the fancy brands can have that problem. Mine
put noise (herringbone pattern) on the TV set. And
to my shock, when I opened it up, I did find there
were filter components in place, so there is something
else wrong with that design. (The filter should have
removed the residual noise.) The Antec supply produces so
much interference, it causes my ADSL modem to lose sync
and drop the line! The ADSL modem and Antec supply,
happened to be plugged into the same power strip.
With the Antec removed from the picture, my modem
has returned to being rock solid. Now, that's a
noisy supply. That's what happens when it's really
bad.
Paul