[Premium-Rx] AC mains Filter Info

Wed Sep 6 00:36:46 EDT 2006

Hi Ed & group,

I considered a mains filtering project some years ago, but canceled it after
doing the test George suggests below. In addition I made recordings of
reception on several frequencies in the band where I listen while a receiver
was operated on mains, batteries and batteries with the entire house
disconnected from electricity (main fuses removed). I compared the
recordings to see how bad the difference was. There was no significant
difference... 

73 de OJ

www.kongsfjord.no <http://www.kongsfjord.no/> 

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From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org] On Behalf Of George Georgevits
Sent: 6. september 2006 03:45
To: Premium Rx; Edward Sylvester
Subject: RE: [Premium-Rx] AC mains Filter Info

Hi Ed,

Not an easy question to answer! Personally, I would not spend that much
money on filtering. The benefits aren't that great. Sometimes you can go to
a lot of trouble filtering the mains, only to find that interference is
generated by equipment on the filtered side (eg. computers, fluoro lights,
TV's, or anything that has an SMPS inside.

The first thing I would try is to turn on the receiver at the location where
you are proposing to operate it and listen to it when the antenna is
terminated with a coax 50 ohms termination. If there is no significant
noise, you are in business, and there is no need for a mains filter at all.
If there is interference, try adding a few ferrite clasps to the receiver
mains lead-in. This can be a low-cost but effective approach to reducing
conducted interference. Even 10 clasps don't cost very much, and can make a
huge difference.

The other thing you must do is ensure that your receive antenna is located
well away from known sources of interference, such as power cables and power
lines, and that you use coax for the antenna lead-in, so that you are
shielded from possible interference pickup on the lead-in. This will require
some form of matching to your receive antenna at the end of the coax, but it
is well worth the effort.

Hope this helps.

Regards,
George Georgevits

VK2KGG

-----Original Message-----
From: Edward Sylvester [mailto:navydude1962 at yahoo.com]
Sent: Wednesday, 6 September 2006 11:21 AM
To: George Georgevits
Subject: RE: [Premium-Rx] AC mains Filter Info

George;

Do you think this is the best way to go for my application, which to is to
minimize noise when listening to shortwave?

George Georgevits <georgg at bigpond.net.au> wrote:

Hi Ed,

Had a look at the specs you sent. Typical of most specs I have seen - almost
meaningless! They don't tell you whether the measured insertion loss is from
leg to ground or leg to leg. So clearly one of these is missing. And also
they don't tell you anything about the common mode loss. Not a whole lot of
use!!! The box looks formidable though, and I guess that is what sells the
product. 

Regards,
George Georgevits 

  _____  

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