On Wed, 2012-07-04 at 15:41 -0400, Paul Christensen wrote:
> > According to the schematic on the side, it consists of 2 x 2.5
> > mH indutors, one in series with each leg, a 2200 pF cap shunting the
> > line input and 0.1uF capacitors from each leg to ground on the load
> > side.
>
---snip---
>
>
So much for part 15.
-Original Message-
From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com]
On Behalf Of Bill Wichers
Sent: Wednesday, July 04, 2012 6:34 PM
To: k...@bellsouth.net; TOPBAND@CONTESTING.COM
Subject: Re: Topband: Progress with ugly computer noise
A
A lot, probably most, of the really cheap UPSes are just switching step-up
converters. The easy way to spot them is from the crazy ratings like "1000va"
but only 3 amps (which should be about 360va). They sell them based on people
thinking "bigger is better" even though a .36 power factor is pre
> Total common mode inductance is 1 times L, not two times L. This is
> because the windings are parallel with near infinite mutual coupling. It
> is exactly like a bifilar filament choke.
Tom,
Run it in any SPICE variant as proof that in CM, total apparent inductance
is 2*L. For example, two
> It's generally two inductors wound on a single core for common-mode
> choking.
> The result is that total common-mode inductance is 2*L while
> differential-mode inductance cancels and equals zero.
Total common mode inductance is 1 times L, not two times L. This is because
the windings are par
FB - that explains the semi-circular arrow between the two inductors on
the schematic - I wasn't familiar with the notation. I don't know the
whys and wherefores, so I just picked the most elaborate of the several
filters they showed on the catalog page - as I recall, it cost around
$10 plus s
> According to the schematic on the side, it consists of 2 x 2.5
> mH indutors, one in series with each leg, a 2200 pF cap shunting the
> line input and 0.1uF capacitors from each leg to ground on the load
> side.
It's generally two inductors wound on a single core for common-mode choking.
The re
Qualtek makes a neat little filter designed to replace the power input
connector on a noisy supply. It fit into mine - one of those with the
jumpered filtering components - and completely suppressed any audible
noise. According to the schematic on the side, it consists of 2 x 2.5
mH indutors,
.
Tom
K6VCR
-Original Message-
From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com]
On Behalf Of ZR
Sent: Wednesday, July 04, 2012 9:59 AM
To: Wes Attaway (N5WA); j...@audiosystemsgroup.com; topband@contesting.com
Subject: Re: Topband: Progress with ugly computer noise
@contesting.com
Subject: Re: Topband: Progress with ugly computer noise
Ditto on the Antec, Ive been using them on both the higher end PC's Ive
built for several years and I dont have to keep upgrading as I change or add
things. Very cool running too.
Carl
KM1H
- Original Message -
04, 2012 12:42 PM
Subject: Re: Topband: Progress with ugly computer noise
> Unless there is something unusual about the existing power supply you
> could
> consider replacing the supply with something like a good Antec or Cooler
> Master unit. Online prices for 500W supplies are $50
On Wed, 2012-07-04 at 09:14 -0700, Jim Brown wrote:
> On 7/4/2012 6:10 AM, Bill Cromwell wrote:
> > Next I'll be getting my hands on some ferrite core materials and looking to
> > see just how far I can reduce the noise.
>
> When faced with a noisy computer, the first thing I'd try (other than
>
That sounds like the power supply is missing the usual common-mode input filter
that switching power supplies nearly always have.
There are companies like corcom that make emi filters for the line. Some of
these filters are integrated with the IEC power connector for the power cord.
If your pow
---
-Original Message-
From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com]
On Behalf Of Jim Brown
Sent: Wednesday, July 04, 2012 11:14 AM
To: topband@contesting.com
Subject: Re: Topband: Progress with ugly computer noise
On 7/4/2012 6:10 AM, Bill Cromwell
On 7/4/2012 6:10 AM, Bill Cromwell wrote:
> Next I'll be getting my hands on some ferrite core materials and looking to
> see just how far I can reduce the noise.
When faced with a noisy computer, the first thing I'd try (other than
replacing the noisy supply) would be a multi-turn choke on the
On Wed, 2012-07-04 at 10:15 -0400, W8ZV wrote:
> >
> Hi Bill!!
>
> Just for reference, my HP generates NO noise. It is possible to get
> clean supplies, although I can't tell you what is in this box. This was
> purchased as a complete unit and came through a government purchasing
> sourc
On 7/4/2012 9:10 AM, Bill Cromwell wrote:
> Hi,
>
> I have been limping along with a really ugly replacement power supply in
> my big computer. It's networked (think of internet tools). I could hear
> *nothing* on my radios aside from the racket made by that power supply.
> I even found my power su
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