On 10/10/2012 12:08 AM, Tony wrote:
On 10/9/2012 10:23 AM, qrv@kd4e.com wrote:
Tony, Do you have a common electrical system? Could his circuit have a
bad ground or neutral and
it is using a path through yours? David
Hi David:
Common in that the power comes into our homes off the same power lines.
That's true in most subdivisions. The question is, are you fed off the
same transformer?
I'd be interested to know if the noise could travel from one home to the
next via the power lines because of a faulty ground.
If it's the same transformer the ground can be just fine. You will find
that many times the devices that use the power line in the home for
internet and TV can talk to all the homes fed from the same transformer
and that can be a real PITA.
Like in the old days with VCRs that ran the output on Ch 3 or Ch 2. Some
of them could be heard a 1/4 to 1/2 mile away.
Then there were those who just wired everything together instead of
using an A/B switch and your VCR was tied to a high gain antenna that
put out a pretty good signal.
Which BTW there are still a lot of attic and antenna mounted preamps no
longer used but still wired to the TV with cable. Remember that channel
18's audio sub carrier(think it's the sub carrier) is on 145.25. Even
without power on them they can still receive and mix a strong 2-meter
signal and retransmit it. Our only saving grace is that if we hear them
they definitely will hear us.
I was able to dump the cable system for an entire town by transmitting
on 145.25 mobile. OTOH I did this while demonstrating the problem to the
service guy for the cable company. He insisted that they couldn't hear
us until I keyed up out in the parking lot. Their cable system was a
whole lot cleaner after work the next day and by the day after that I
could no longer find any places where I could hear 145.25.
73
Roger (K8RI)
Tony
I recently discovered that my neighbors CFL lighting was causing RFI. I
managed to get close the light with a portable HF rig and found the
noise was identical to what I was hearing in the shack; same
frequencies, same noise characteristics. I should mention that the bulb
was burned out.
The problem with pointing the finger at the light as the only RFI source
was that the noise would shift in frequency when I turned a light switch
on and off in my home! I recorded the frequency shift "trick" on video:
http://www.youtube.com/watch?v=EYHbpLfQ1gc
I shut the mains to see if the noise was coming from my home, but it was
still there with the breakers off. The light switch had no effect on the
noise as long as the mains remained off.
Long story short:
The noise went away immediately the moment my neighbor removed the
burned out CFL. An identical CFL that was working emitted much less
noise. He hasn't replaced the bulb yet so we'll have to see what happens
with the new one.
The puzzling thing about all this is how a light switch in my home could
have an effect on the noise coming from a neighbors CFL? It doesn't
appear coincidental because the light switch "trick" hasn't happened
since my neighbor removed the CFL. It's been a while now and all is
quiet.
Any ideas?
Tony -K2MO
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