[RFI] RFI Noise - Part II

David Cole dave at nk7z.net
Sat Jul 6 21:14:15 EDT 2013

Wow...  You get a free prostate exam for life!!!  :)  

Kidding, nice work!
Thanks and 73's,
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On Sat, 2013-07-06 at 16:45 -0400, K8TB wrote: 
> I have to drop in my story, which was solved 2 weeks ago.
> On our local repeater, a fellow ham who works at the large local 
> hospital, was concerned as one of the doctors there was being charged 
> with interference to a CB'er. I contacted the doctor, and cool part was 
> that he very much knew the difference between amateur radio and cb'ers. 
> I then contacted the CB'er.
> He was not easy to deal with. Somewhat belligerent. I also did not trust 
> any of his "troubleshooting". He was adamant that the doctors house was 
> causing the problem. The noise the CB'er was being bothered with came on 
> around 9:15 PM, and lasted for 12 hours. I found this when I visited him 
> with a ham buddy. I drew on all my knowledge of Law n Order to ask the 
> questions properly.
> It was 9 PM, so he then drove his SUV with his CB rig (on Channel 37), 
> to the power pole in front of the doctors house. The CB'es antenna/tower 
> is about 500 feet away. Right at 9:22PM, his mobile CB rig went from S2 
> (he had two preamps in series in his mobile!) to S9. I had my FT-817 
> dialed into 27.375 (Channel 37), and my National DF loop. My noise went 
> up to an S2. But, I immediately could tell that the signal was not 
> coming from this area. Every 100 feet, I could tell I was closer. The 
> noise was a very broad band AC buzz. I ended up around 500 feet away 
> from the doctors power pole, and then I could not get a null, as I had 
> all kinds of secondary power lines overhead. The noise was now S9 ++
> I went back to my car, dug out my Arrow 3 element 2 meter beam, and my 
> VK3YNG sniffer. From my car, I walked back to my last spot, and as I 
> walked, the noise, on 2 meters, very sharpley pointed to one house. The 
> home owner was working on a car just outside his garage. I called to him 
> from the sidewalk. My ham radio buddy joined. I explained that we were 
> looking for electronic noise in the neighborhood. He told me, "Ya, 
> something bothering a lot of stuff in my house!". Holding teh 
> sniffer/beam to his power meter caused the sniffer to go to 60 Db 
> attenuation.  I told him that to the best of our ability, the noise was 
> coming from his house. I then told him that the noise was on for 12 
> hiours and off for 12 hours. He then told me that he had grow lights on 
> a 12 hour time, but they were not due to come on until 10 PM. I asked if 
> we could tun off the timer. He said, no wait here. He went downstairs, 
> and the noise was gone in 30 seconds. He came back, and could not 
> apologize enough. He had checked several of his electronic devices and 
> the noise was gone. He never made the connection.
> We offered to have a look see at the ballast, and he said, "No!". Now, 
> could he be growing pot? Not necessarily. Many people don't want 
> strangers in their house. I understand that.
> The CB'er? Because he was parked by the doctors power pole when the 
> timer kicked in, it had to be the doctor. If he had just backed up 500 
> feet, he would have learned more. Reminds me of so many mistakes 
> beginning DF'ers make. The CB'er also told us "He wanted words with this 
> neighbor". We told him no.
> My ham buddy knew the neighbor with the bad ballast from a work 
> situation, and politely asked to come back in one week to verify the 
> noise was gone. The neighbor was very wiling for that. That neighbor was 
> insistent that the bad ballast would be gone. I felt he was embarrassed.
> The doctor was very very happy. No, he did not offer a free exam for our 
> work!
> But years of monitoring this forum helped me in troubleshooting this. 
> Thank you to all for the hints from the past.
> Tom Bosscher K8TB
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