Modern electronics and radio interference

[Brian Gaff]

It seems to me that although things like lighting and power supplies are more efficient and small, the care taken to suppress the sort of crud they radiate down the mains is ridiculous. As a person who has had the hobby of listening to the vast expanses of the radio spectrum, and finding everything CE marketed, I have to ask myself if either the specs are too lenient, or are ignored. Obviously its the switch mode psus that are most of the problem, as a system of dropping a mains voltage down to that needed by the equipment by using directly connected high frequency and none to clean waveforms makes transformers smaller and more efficient. Short of going to a remote part of the country and running from batteries, I think the problem has gone too far now. The train has left the station, so to speak. People say that the lack of the use of AM medium and short wave radio is because of DAB and the internet, but a whole lot of the problem is the noise floor in any built up area. Obviously if you were making electronic stuff yourself, you could make it clean, but because everyone else buys the cheap Chinese crap lights and wall warts, my hobby is doomed. Brian

[mm0fmf]

It ignored and Ofcom don't see it as their business to ensure the airwaves are kept clear of s**te.

People want cheap shit. That's what they get. If it buggers up something else they don't care as long as the something else isn't theirs.

[Jim GM4DHJ ...]

chinky crap is the problem

[Jim GM4DHJ ...]

ofcon couldn't wipe their own arse

[Alan B]

Is this MFJ device worth a try?

[Fredxx]

My experience is that they are largely ignored and only when there are extra safety criteria such as medical equipment will a full suite of tests carried out.

The UK manufacturer or UK import is responsible for any testing even if used in a one-off research environment.

I have imported items through Ali-Express and never asked for the item's technical file yet I am technically responsible.

Of all the things you cite these have least legislation as they operate at too low a frequency for much of the testing. The mains harmonic requirements are pretty lax.

Many amateur astronomers say the same about skies. I guess it's progress for the many at the expense of people like you.

The only positive thing about mains born interference is it's very local, hence your meets in rural areas frequented by doggers? :-)

[Rod Speed]

Brian Gaff [e-mail] wrote

Why should we all be paying more so that a microscopic minority who choose to have that hobby can do that ?

In many caces the CE mark is a lie.

And doing that won't fix the problem with over the horizon radar etc.

Yep, you are pissing against the wind.

And they are correct about that.

Nope, that isnt the reason hardly anyone is silly enough to still be using AM medium and short wave radio

And like I said, why should we all be paying more so that a microscopic minority who choose to have that hobby can do that ?

[Jim GM4DHJ ...]

probably but not MFJ

[Brian Gaff]

Tried all of these phase out your noise devices. Unfortunately, due to it coming in from all around getting an anti phase signal is impossible. The other device is of course the digital noise reducer made by BHI, but you cannot make a silk purse out of a sows ear as the saying goes, and all it does is use fast Fourier transforms to match the noise spectrum and then let the audio through, but the more noise there is the more terrible the actual audio sounds. It is basically a filter after all. No the only way would be to find a convenient place with no noise and build your aerial farm there, all under remote control over the internet, and shove a decent receiver there with an internet feed and all the controls at your end. These do exist on the web of course, Web SDRs abound these days, but very fiew have sufficient controllability for each user, and have a limited number of users. Besides half the fun is designing aerials and tweaking things to get better reception. Not much good if you have to take a taxi ride there if anything goes wrong, let alone of getting an internet feed in the middle of nowhere, and a mains connection and renting the land off of the farmer and getting planning permission. Brian

[Brian Gaff]

I think you are rather missing the point here. If you are going to make a device efficiently, then the last thing you should be doing is generating RF with harmonics to infinity. It seemingly is possible to make swictch mode devices that do not saturate the ferrite cores of the small transformers, and do not produce spikes of crud.Its a trend toward cheap and cruddy making of things. Back in the days of 405tv, there was uproar when the timebases of the tvs started to interfere with long wave radio. In the end most makers of sets started to screen the power devices or design them not to radiate and unless you were right up close you never heard the whine any more. Of course I guess you could say that Long wave was used a lot more in the early days of TV, and so there were more people to moan. I'd like to think that if a job is worth doing its worth doing well, and yet nobody seems to think this is what good design is all about. Brian

[Fredxx]

Good design is to minimise cost and still stay within the rules of RF emissions.

That is a job that is generally done well, and indeed has to be in a competitive world.

The line output timebase of a 405 line set was at 10.125kHz, and with a lot of energy in a resonant circuit. It was always going to leak a small amount of 20th harmonic.

I thought there was more an issue with 625 line sets, where the odd 13th harmonic would beat with 198/200 kHz? Especially with colour purity adjustments that deliberately created odd harmonics.

[Rod Speed]

Brian Gaff [e-mail] wrote

Nope.

In fact f*ck all of the energy produced is wasted in those harmonics.

And the alternative approach to a switch mode power suppy or plug pack wastes FAR more in the transformer.

AND the designer doesnt actually give a shit about ultimate efficienty anyway, they care about the cost of the components needed to minimise the harmonics.

Yes, but that costs a lot more component wise than the much more basic designs they choose to use.

And now only a microscopic handful of people like you bother with long wave radio at all, so no one in chine is silly enough to spend more on plug packs so that that microscopic handful can continue to do what.

Of course there was. And what drove TV design then was completely different to what drives the design of switch plug packs in china today

Those who design switch plug packs in china today dont operate like that. Can't imagine why for the life of me.

Some still do, most obviously with Apple and rolls royce jet engines, but not those who design switch plug packs in china today

[Rod Speed]

Fredxx [e-mail] wrote

There are no such rules.

[charles]

Maybe not is Auzzie land, but there are in the EU. Possibly they still exist in the UK

[Fredxx]

This is UK.D-I-Y and I can assure you there are in the UK.

[Fredxx]

Inefficiency creates heat that has it's own issues. He does care about efficiency although that may be a secondary consideration over cost.

You've obviously never designed anything of value.

[Rod Speed]

charles [e-mail]> wrote

Have fun explaining why Brian is bedevilled by all those steaming turds of switch mode plug packs from china.

Have fun explaining why Brian is bedevilled by all those steaming turds of switch mode plug packs from china.

[Rod Speed]

Fredxx [e-mail] wrote

Must explain why Brian is bedevilled by all those steaming turd switch mode chinese plug packs.

[Rod Speed]

Fredxx [e-mail] wrote

The inefficiency of those harmonics does not produce enough heat to matter in a chinese switch mode plug pack and even the best of the switch mode plug packs still have those harmonics, they are just contained within the decide much better and so a microscopic more heat is retained in the devide.

No one is actually stupid enough to produce sine waves at the frequency required to avoid radiating the harmonics and doing the would produce MORE heat if they did.

Not the microscopic lower efficiency that is involved with the harmonics being discussed and there is no way to avoid that which doesnt involve far LESS effiency by say going for a sine wave instead.

No may be about it with a switch mode plug pack, f****it child.

<reams of your shit any 3 year old could leave for dead flushed where it belngs>

[Nick Odell]

How many amateur radio enthusiasts are NOT simultaneously transmitting via the internet? Obviously that knocks QSL acknowledgements on the head but how many folk are even sending QSL cards? By post?(fat chance of that getting delivered these days) By email?

In an age when students will no longer have to use handwriting to sit exams, how is the Quill Pen Society expected to function?

My personal foible is film photography and since it's getting harder and harder to buy good, fresh film, I'm even experimenting with making my own glass plates because at least I can coat them with my own emulsions. The fact is that if you or I want to carry on with an esoteric hobby, we have start from the position that the rest of the world is moving on and we have to adapt.

Nick