Re: [SDRSharp] Overcoming local noise.


Martin <kb0hae@...>
 

Hi Chris. Did you order a generic power supply, or an HP brand replacement? I had a similar experience when I bought a generic supply as a spare for my IBM T43. I got rid of it and got an original IBM supply. No noise from the IBM supplies.

Poorly designed switch mode power supplies are a real problem these days. Many electronic devices including some wireless (WiFi) routers use these RF noise generators. I have many CFL bulbs, none cause interference unless they are less than 6 inches from an antenna. I have read that plasma TVs and many newer furnaces cause a lot of interference too.

I have managed to eliminate most of the noise sources here, and my neighbors are farther away than in most local areas here. Turning things off is not enough. You need to unplug things, since many devices have noisy internal power supplies that are not turned off by the power switch. Do this one thing at a time, leaving things unplugged as you go until you find the culprit.

In the case of external supplies, sometimes you can replace a switch mode supply with a non-switching supply. I managed to find Netgear routers (one as a spare) that have non-switching supplies. Previous routers had very noisy switching supplies.

ttyl

On 08/24/2013 11:46 PM, feralmet wrote:

A few days ago, the 18.5 volt power pack for my HP 311 notebook
failed, so I ordered a new one. The new power pack obliterated radio
reception all over the house, and even interfered with FM radio
broadcasts received on a good outdoor co-ax fed antenna. No amount of
filtration with ferrite blocks or mains filters made any difference.

Things are just going from bad to worse with some of these
switch-mode power supplies.

Other notable noise sources are the charger for my electric bike and
my variable heat soldering iron. Low wattage flouro lamps were a
problem sometimes too, but I have replaced those with LED globes and
they seem to be silent.

So what I am saying is that it's worth investigating possible noise
sources by turning things off around the house. In my case it was
causing considerable de-sensitisation of the dongle, both on VHF and
HF (with HamItUp upconverter).

Hope this might help a newbie or two....

Cheers, Chris VK3CJS




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