[RFI] led bulb test

[David Robbins]

Bought a relatively expensive single 100w replacement GE LED bulb today just
to try a new one out after my disappointment years ago with an early product
that trashed everything.  The part numbers and stuff off the box are:

 

PC: 65935

Desc: LED15DA21/BX

Res. # 1517294

Sku: 0 43168 65935 2

String under sku: CNTLEDA211DM15GE65935ASCH-02

 

It cost $15.29 at PriceChopper/Market32 in Pittsfield.

 

I ran some un-reproducible tests to see if it was acceptable for use near my
station. my basic conclusion is that it is adequately quiet, I can not hear
anything from it on my outside antennas.  To try to find discrete signals or
overall noise I ran a couple tests with an sdr connected to a test lead
wrapped around the fixture and the bulb itself to find conducted signals or
those radiated in the near field.  First, the fundamental frequency of the
switching supply is about 85khz with a rather wide noise band up to about
135khz.  The wide noise band spreads out the energy of the harmonics over a
fairly wide bandwidth so individual frequencies of harmonics can't be seen
like a more stable source like monitors or computer clocks can.  With my
test lead loop around the fixture (an incandescent track light) I could see
noise about 3db above the noise floor above about 25MHz, below that I saw no
change in the noise floor and no discrete frequencies.  I could not hear any
increase in the noise floor with my 10m antennas aimed at the shack from
about 200' away or on 15m from about 100' away.

 

 

 

David Robbins K1TTT
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