Topband: switching pwr supply noise problem

[Tim Duffy]

I have had good luck fixing these noisy computer power supplies by
putting a high quality AC line filter in the computer AC line cord. The
W3NQN AC line filter and the ICE AC line filter work great.

Last year I tracked down a nasty 160 meter buzz to a neighbors house.
This year 3 more have popped up, but they are all on 80 meters. I use an
Icom R-1 for a portable receiver. Look for the same buzz sound every 30
KHz (signal strength may very).

I sure wish the FCC would mandate strict standards (European power
supply RF filtering is much better) for how much switching supply
garbage can be emitted down the neutral (ground) of the AC service. 160
and 80 meters would be a much cleaner place!

73,
Tim K3LR


Roger Graves wrote:

> Story of a ham's Sunday.
>
> I finally get around to trying to track down the noise sources that
> have gradually sprouted up on 160. Buy a portable shortwave rx
> and proceed to walk around the neighborhood to find which of my
> neighbors is guilty of having something nasty.
>
> Hmm, noise decreases as I leave the front door and walk down the
> driveway.
> OK, could this be? So, procede to go back in the house and walk
> around the house. Lots of noise. So, to the circuit breaker. Open
> one at a time, shrieks from various family members, flashing
> clocks everywhere. Noise doesnt go away on any breaker. Repeat,
> more shrieks. OK, throw that big house breaker lever. RF noise
> drops. Hmm. OK, open all circuit breakers, and close one at a
> time. 3 separate circuits show increase of noise. Take a break.
>
> Circuit 1, hamshack area, is loudest! Unplug ethernet router pwr
> supply. Big drop in noise. Unplug cable modem pwr supply, noise
> goes away. Both are small switching pwr supplies.
>
> Circuit 2, daughter's room. Mass of wires, cables, candy wrappers,
> month's worth of school lunch containers behind desk. Unplug one
> thing at a time. HP computer printer power supply, switching type,
> is the noise source.
>
> Circuit 3, living room. Sony TV (when on) and Sony VCR (whether
> off or on) turn out to be generating 160 mtr noise.
>
> Wind power cord on a toroid (10 turns on 77 mix). This kills the TV
> & VCR noise, progress! This does nothing for the louder printer,
> router and modem power supplies though.
>
> Leave those power supplies unplugged and operate on 160, with
> quietest noise level in some time!
>
> Anybody have any suggestions on quieting those little noise
> generator power supplies? My only thought at the moment is to
> build new transformer supplies or to substitute an old computer
> power supply that is RF quiet.
>
> Thanks for any suggestions,
> Rod
> VE7VV
> Victoria, BC
>
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