[600MRG] Distance from powerline question

[sbjohnston at aol.com]

On a related note, don't always assume wideband RF noise problems are "powerline" noise.  The last three guys I helped with their noise problems all had noisemaking devices right in their house - once those were unplugged they could hear normal MF and HF background hiss with little or no buzz.  

One guy had three devices making the lion's share of the interference:  a cellphone charger, the power adapter for his cable modem, and a DVD player.

The second of these fellows had a TV set making lots of noise, even when turned off.  We put it on a power strip so he could positively cut the power to it.

And the third guy had a microwave oven, a cellphone charger, and a rechargable tool charger making excessive RF noise.

All these devices have switching power supplies which I feel were responsible for the RFI.  The TV set made a different, grinding sort of noise, so it may have had other sources of the interference but I still put my money on a switching power supply (maybe higher voltage type for the plasma display).  We used older AC adapters of similar ratings from thrift stores to replace the switch mode types supplied with portable devices.

All three guys were originally certain that they had powerline noise in their neighborhood.  I convinced them to turn off all the breakers in their house while we listened to the noise on a battery powered Sony ICF-2010 receiver.  When the noise dropped to nil with the house power off they were astonished.  We then started turning breakers back on one at a time to identify which rooms had the worst noise sources.



Steve WD8DAS / WH2XHY

sbjohnston at aol.com
http://www.wd8das.net/
--------------------------------------------------------------------
Radio is your best entertainment value.
--------------------------------------------------------------------