My calculations assume that the LED lamp conducted emissions are at the FCC limit at a single frequency in the 160 meter band. This is not real world.
I'll buy a lamp and characterize the conducted emissions. Dave WX7G On Apr 6, 2012 4:44 PM, "DAVID CUTHBERT" <[email protected]> wrote: > ---------- Forwarded message ---------- > From: "DAVID CUTHBERT" <[email protected]> > Date: Apr 6, 2012 4:42 PM > Subject: Re: Topband: Home Depot LED bulb interference. > To: "GeorgeWallner" <[email protected]> > > LED lamps no doubt comply with FCC conducted emissions. The noise is almost > entirely differential mode. Think of a signal on an open wire t-line; it > does not radiate (much). > > But, the asymmetry in the AC power system causes differential to > common-mode conversion. Common-mode current on an open wire feedline > radiates (a lot). > > The primary asymmetry I see is the neutral wire to earth ground. I ran a > NEC sim of a simplified house AC power with feed wires to a power pole. The > signal induced into a 160 meter dipole next door is S-8 from a single LED > lamp at the FCC limit of 2 mV differential into 100 ohms. > > Disconnecting the AC earth ground wire drops the signal by 40 dB. Ferrites > clamped onto the earth ground wire could help. > > This is crude and preliminary but is interesting as I'm an EMC design > engineer as well as a ham. > > Dave WX7G > On Apr 6, 2012 4:22 PM, "GeorgeWallner" <[email protected]> wrote: > > > On Fri, 6 Apr 2012 11:57:15 -0700 (PDT) > > "Jim F." <[email protected]> wrote: > > ...Since this bulb complies with > > > part 15 of FCC rules > > > > It is marked to comply, but it may not. (Part 15 > > compliance is self-certified. It would be interesting to > > test it against Part 15 requirements. > > > > I believe that one of our potential defences against the > > worst offenders is to bring the attention of retailers to > > the pontial risks of selling non FCC comliant products. > > The more cautious they get the better off we will be. > > Returning it to the retailer is a good start in that > > direction! > > > > George > > _______________________________________________ > > UR RST IS ... ... ..9 QSB QSB - hw? BK > > > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
