[RFI] led bulb test

[W0MU Mike Fatchett]

I have been using 60w led bulbs for a while.  Have not noticed any new 
noise.  They are pretty inexpensive with the power companies kicking in 
on the costs.

W0MU


On 11/9/2016 10:22 AM, David Robbins wrote:
> 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
>
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>
> It cost $15.29 at PriceChopper/Market32 in Pittsfield.
>
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>
> 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.
>
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> David Robbins K1TTT
> e-mail:  <mailto:k1ttt at arrl.net> mailto:k1ttt at arrl.net
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> telnet://k1ttt.net:7373
>
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