Re: HF interference from WiFi router

Bert Hyman wrote:
In news:Xns9AB559CAC966AVeebleFetzer@xxxxxxxxxxxxx Bert Hyman <bert@xxxxxxxxxxx> wrote:

In mk22k.17746$qP.9885@trnddc03">news:mk22k.17746$qP.9885@trnddc03 "JB" <nospam@xxxxxxxxxxxx> wrote:

Try feeding power to it from a battery source, rather than the wall
wart that comes with it. See what that does for it.



I was thinking same thing. He has a swiching wall wart that responds
to the current draw when the WiFi TX is enabled.

Exactly my problem with a Wirespeed DSL modem. Cheap wall wort would
spew all over the spectrum after a few minutes under load.
Thanks for the suggestion about the power supply.

I'll be cobbling together an appropriate cable to feed the modem from a
stiffly regulated analog supply. If that works, I'll just build a little
supply to replace the wall wart.

That seems to be it.

I powered the router from an Astron RS-12A and the interference was gone.

Don't know if the wall wart itself is the source of the problem or if it drops output under load and causes the router to misbehave, but it's an easy enough fix.

I doubt you'll find that lower voltage is the culprit, if my personal saga with noise is any indication... ALL of my noise problems were traced to various cheapie wall warts (mostly switching type) included with various cell phones, net switches, cable modem, etc... and each worked just fine over a fairly wide voltage range when connected to a good analog lab supply. In each case, they tended to just cease functioning at some point as the voltage dropped, and I didn't get any broadband noise from them any place in the testing cycle. Plug the wall wart back in, and some even put out nasty broadband noise with little or no load, though all of the offenders put out plenty of hash at full load, even using a purely resistive load and an electronic load I happen to have left over from power supply development days.

It was an easy task to put together a decent but cheap analog power supply with a few 3 terminal regulators to power the devices in question, and all of the hash was gone (for awhile). I don't exactly know how, but a few of the things somehow crept back into the house, and it's time to go on another extermination binge for the wall warts again...

Good Luck...
--Rick AH7H

.

Relevant Pages

  • Re: power adapter... will it explode?
    ... I lost its wall wart and found a wall wart for another device, ... > The extra 2 volts may or may nto harm the speakers, ... their rated voltage even at full rated load. ... In your case, the load may be more than its rated 400mA, which may be ...
    (sci.electronics)
  • Re: 12 volt power source?
    ... Multimeters don't apply much of a load by design. ... the load to have full regulation. ... buy the wall wart type. ...
    (rec.models.railroad)
  • Wall wart current draw
    ... A while back there was a discussion about why wall wart transformers that ... were not under load would draw no current. ... Anyone recall that thread? ...
    (rec.crafts.metalworking)
  • Re: Taking the hummm out of a circuit
    ... >> Looks like you are trying to get too much from the wall wart. ... Well, if the input is above 12 volts DC and the load is only 5mA, ... Use the DMM to measure AC voltage at the output. ... You could try a small capacitor on the ...
    (sci.electronics.basics)
  • Re: 60Hz noise making its way into my test
    ... acquisition program to test a product his company makes. ... I'm reading voltage values of his device, it outputs an AC square wave ... makes it a good candidate for replacement. ... the wall wart (usually on the back of the supply, ...
    (sci.electronics.basics)