Just a quick straw poll...

What are people's opinions of mains filters, upgraded power cables etc?

Have been doing some investigation and there may actually be something
in this. Not talking Russ Andrews style £250 mains cables here, more
like sticking a plug with a filter onto a standard IEC lead, and
possibly using one of those Masterplug RFI filtered 4-way blocks.

Has anyone done any serious experimentation on this? I did hear a quite
convincing demonstration at the Sound & Vision show in Bristol a few
years ago, but the mains there is probably a lot dirtier than your
typical home installation.

What myself and a few others have figured out is that the level of RFI
introduced onto your ring main by something like the switching PSU in a
typical PC is quite high.

Opinions, people?

--
Glenn Richards Tel: (01453) 845735
Squirrel Solutions http://www.squirrelsolutions.co.uk/

IT consultancy, hardware and software support, broadband installation

"Glenn Richards" wrote in message
. uk...
Just a quick straw poll...

What are people's opinions of mains filters, upgraded power cables etc?

If you're going to upgrade your power cable you really ought to do it all
the way back to the substation, otherwise it's a bit pointless...

Rich Wilson wrote:

If you're going to upgrade your power cable you really ought to do it
all the way back to the substation, otherwise it's a bit pointless...

Well that was my initial thought... but apparently not.

In a conversation I had with a friend, we determined that power cables
are good at carrying low frequencies, and poor at carrying higher
frequencies. So RFI picked up at the substation won't make it to your
house, but interference sources in your house will cause RFI to reach
your kit.

For the record, at the moment my hi-fi equipment is plugged into a surge
protected 4-way strip, nothing more elaborate.

--
Glenn Richards Tel: (01453) 845735
Squirrel Solutions http://www.squirrelsolutions.co.uk/

IT consultancy, hardware and software support, broadband installation

"Glenn Richards" wrote in message
...
Rich Wilson wrote:

If you're going to upgrade your power cable you really ought to do it
all the way back to the substation, otherwise it's a bit pointless...

Well that was my initial thought... but apparently not.

In a conversation I had with a friend, we determined that power cables are
good at carrying low frequencies, and poor at carrying higher frequencies.
So RFI picked up at the substation won't make it to your house, but
interference sources in your house will cause RFI to reach your kit.


That actually isn't true. Until recently, when the amateur radio community,
via first the R.A. and then Ofcom, managed to get it stopped, there were
tests of a system call PLT ( power line transmission ). This system placed
RF carriers up to about 30MHz, onto the domestic mains supply. The purpose
was for data transmission of the broadband internet variety. However, no
matter how balanced the mains supply is, it still isn't good enough to
prevent common mode currents at these sorts of frequencies, and therin lies
one of the major problems with this technology. The whole mains supply
network, from the injection point at the substation, to your house, has a
tendency to radiate like a dammed great antenna, at times causing serious
interference to legitimate receiving equipment - and thats not a hifi, it's
a radio.

It was eventually determined that there were better, more efficient, and
less troublesome technologies available for broadband delivery, and dropped,
at least here, although I believe that there may still be some places in
Europe where the tests are still happening. Bear in mind also, that the
generating and distribution companies, use this, or a similar high frequency
technology, in-house to carry telemetry data around their grid distribution
network. So, just to recap, the mains power distribution system can
successfully carry HF, as well as LF, all the way to your house.

As far as interference escaping from your equipment goes, it certainly
shouldn't, under strict EU regulations. Any electrical / electronic
equipment sold in the EU, should carry CE certification, and one of the
requirements of this certification, is that the equipment does not either
send crap out onto the mains, above a certain very low level, nor directly
radiate it. Further, the equipment's normal performance must not be
compromised in any way, by the presence of high level RF or pulse
interference, either introduced into any outside-world ports, the mains
supply being one such, or by direct radiation.

So again, to recap. If the equipment is reasonably recent, and the
manufacturer is playing by the rules, it should not feed any crap onto the
mains supply. If your hifi manufacturer has played by the rules, his kit
should not respond to any such crap, that got onto the mains by any route.

All that said, there's no harm at all in helping your kit out by fitting a
surge arrester plug, which contains VDRs, and if you find a good one, it
should have RF suppression in the form of LCR in it, as well. Worth a tenner
for the surge protection at least, and the ' belt and braces ' for the
filtering that should already be in your kit, but I certainly wouldn't pay
any more. Even then, I would probably spend the rest of the week trying to
work out if my money would have been better spent on 4 pints ...

Arfa

Arfa Daily wrote:

In a conversation I had with a friend, we determined that power
cables are good at carrying low frequencies, and poor at carrying
higher frequencies. So RFI picked up at the substation won't make
it to your house, but interference sources in your house will cause
RFI to reach your kit.
That actually isn't true. Until recently, when the amateur radio
community, via first the R.A. and then Ofcom, managed to get it
stopped, there were tests of a system call PLT ( power line
transmission ). This system placed RF carriers up to about 30MHz,
onto the domestic mains supply.

This technology actually exists (possibly at a different frequency), and
works very well.

About 18 months ago some student friends asked me if I could get
broadband around their shared house. First thoughts were WLAN of course,
so I duly ordered a broadband account for them, and set up a wireless
router in a central location, with wireless cards in all the PCs and
laptops allowing everyone to access the internet through it.

Unfortunately, it was a rather large house, and there was a huge dead
spot on the ground floor. So... enter HomePlug.

Whacked a HomePlug powerline networking bridge into the router via wired
Ethernet, and plugged a HomePlug access point in on the ground floor in
the middle of the dead spot. Which solved the problem.

All that said, there's no harm at all in helping your kit out by
fitting a surge arrester plug, which contains VDRs, and if you find a
good one, it should have RF suppression in the form of LCR in it, as
well. Worth a tenner for the surge protection at least, and the '
belt and braces ' for the filtering that should already be in your
kit, but I certainly wouldn't pay any more. Even then, I would
probably spend the rest of the week trying to work out if my money
would have been better spent on 4 pints ...

From a purely objective point of view, it's worth spending a tenner (of
a fiver trade) on a surge protected strip to protect 2 grand's worth of
kit, especially if you happen to live somewhere where there's dodgy
power. Yay rural areas...

--
Glenn Richards Tel: (01453) 845735
Squirrel Solutions http://www.squirrelsolutions.co.uk/

IT consultancy, hardware and software support, broadband installation

It was eventually determined that there were better, more efficient, and
less troublesome technologies available for broadband delivery, and dropped,
at least here, although I believe that there may still be some places in
Europe where the tests are still happening. Bear in mind also, that the
generating and distribution companies, use this, or a similar high frequency
technology, in-house to carry telemetry data around their grid distribution
network.

What over the 475 kV grid?, don't you mean via the fibre optic at the
top running along the "aerial" earth wire?....

--
Tony Sayer

"tony sayer" wrote in message
...
It was eventually determined that there were better, more efficient, and
less troublesome technologies available for broadband delivery, and
dropped,
at least here, although I believe that there may still be some places in
Europe where the tests are still happening. Bear in mind also, that the
generating and distribution companies, use this, or a similar high
frequency
technology, in-house to carry telemetry data around their grid
distribution
network.

What over the 475 kV grid?, don't you mean via the fibre optic at the
top running along the "aerial" earth wire?....

--
Tony Sayer


To Glenn. You've virtually answered your own question there about whether
the mains wiring can successfully handle HF as well as RF, although I was
not actually referring to broadband distribution around the house, rather to
its delivery from the ISP, and this technology has, at least for the time
being, been knocked on the head here, because of potential interference
issues.

To Tony. You're right. In recent years, the electricity companies have
installed fibre optic links, but I'm fairly sure that when they first
started using this method of communicating amongst themselves, they did make
use of the full distribution network, including the supergrid, but I may be
wrong on that. How much power volts are on the line, shouldn't make any
difference. It's still just a piece of wire, with HF skin effect, to the
comms signal. I believe that with the PLT internet trials, the injection
points were at central substations, so I guess that this must have been
working at up to at least the local 11kV distribution level. Just as an
aside, I think that the grid and supergrid operate at 275kV and 400kV, not
475kV. I also have a dim recollection of reading somewhere, that the 25kV
overhead lines on the uk rail nework, were also used for HF telemetry, but
again, I could be going off on one there. Suffering from CRAFTs disease,
don'tcha know ... !! d;~}

Arfa

In article , Glenn Richards wrote:
In a conversation I had with a friend, we determined that power cables
are good at carrying low frequencies, and poor at carrying higher
frequencies. So RFI picked up at the substation won't make it to your
house, but interference sources in your house will cause RFI to reach
your kit.

How do you determine the electrical properties of cables by conversation?

Rod.

Roderick Stewart wrote:

In a conversation I had with a friend, we determined that power
cables are good at carrying low frequencies, and poor at carrying
higher frequencies. So RFI picked up at the substation won't make
it to your house, but interference sources in your house will cause
RFI to reach your kit.
How do you determine the electrical properties of cables by
conversation?

By applying known principles of engineering.

The losses at high frequencies are significantly higher in 2.5mm mains
wiring cable than screened co-ax, if you don't believe me try running a
composite video signal down mains cable (rather than 75ohm co-ax) and
see how far you get.

It's like saying "how can you determine that an Audi Quattro is going to
go around a hairpin bend at 100mph faster than a Ford Fiesta", for example.

--
Glenn Richards Tel: (01453) 845735
Squirrel Solutions http://www.squirrelsolutions.co.uk/

IT consultancy, hardware and software support, broadband installation

On Thu, 16 Mar 2006 13:13:38 +0000, Glenn Richards
wrote:

Roderick Stewart wrote:

In a conversation I had with a friend, we determined that power
cables are good at carrying low frequencies, and poor at carrying
higher frequencies. So RFI picked up at the substation won't make
it to your house, but interference sources in your house will cause
RFI to reach your kit.
How do you determine the electrical properties of cables by
conversation?

By applying known principles of engineering.

The losses at high frequencies are significantly higher in 2.5mm mains
wiring cable than screened co-ax, if you don't believe me try running a
composite video signal down mains cable (rather than 75ohm co-ax) and
see how far you get.

Just as far as you would with coax, if you match impedance properly
and don't mind some intereference.

It's like saying "how can you determine that an Audi Quattro is going to
go around a hairpin bend at 100mph faster than a Ford Fiesta", for example.

Indeed, but a poor analogy, since neither car will achieve this. Lack
of engineering knowledge noted yet again........

--

Stewart Pinkerton | Music is Art - Audio is Engineering