Summary: Just niw the neighbor's electrician removed a LighTech LET-75
power supply and replaced the 12v light with a line voltage lamp. The
fixture was grounded, but the power supply itself had no ground lead.
It was in a metal jbox atop copper pipes for water.
The company's site is http://www.lightechinc.com and the part is a "LET
75 75 Watt Electronic Transformer LDC Dimmable." It has RU markings but
no Part 15, "Patented Made in China." Their website is all Flash-based
and hard to navigate, but you can eventually get to a data sheet, which
has no mention of other acceptance.
He's sending it back to them for a refund, and plans to switch the track
lighting to line voltage MR16's as well.
Leigh/WA5ZNU
Leigh L. Klotz, Jr. wrote:
> I have a buzz that happens some, but not all, nights, and not during the
> day, at least so far.
> On HF, I can hear it 80-20; I haven't tested other bands.
>
> Here is a screenshot of what it looks like in an SSB receiver:
> http://wa5znu.org/2007/10/rfi/rfi.png
>
> The axes are in ms, and the period is close enough to 120Hz that I think
> that's what it is.
>
> Here's what I've done so far:
>
> 1. Rotated a 20m beam and found the general direction, with about a 35
> degree beamwidth.
> 2. Used a simple wire loop on a TH-F6a set for AM on ~5Mhz and found
> it's not coming from my house.
> 3. Found a strong buzz coming from the sodium vapor light in front of my
> house, but it could also be just coupling from the light mast as an
> antenna (same effect for WWV on 5 MHz).
> 4. There is no correlation between the sodium vapor light being on or not.
> 5. I haven't heard it during the day.
> 6. I haven't heard it every night.
> 7. There are other power lines around in the general direction.
> 8. I've been able to hear it from the light mast on 135Mhz but the wire
> loop isn't sensitive enough to find it at a distance; I will probably
> make a wire yagi if I need to do more looking.
>
> So, does this look like power line noise? Or should I be looking for
> something in a neighbor's house that they use at night that also somehow
> emits broadband noise with a 120Hz period?
>
> 73,
> Leigh/WA5ZNU
>
>
>
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