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 telegraph...@gmail.com wrote:
-- Forwarded message --
From: DAVID CUTHBERT telegraph...@gmail.com
Date: Apr 6, 2012 4:42 PM
Subject: Re: Topband: Home Depot LED bulb interference.
To: GeorgeWallner aa...@atlanticbb.net
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 aa...@atlanticbb.net wrote:
On Fri, 6 Apr 2012 11:57:15 -0700 (PDT)
Jim F. j_fit...@yahoo.com 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
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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UR RST IS ... ... ..9 QSB QSB - hw? BK
