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#11
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Hello Harold,
The 4th harmonic at 14.317 is 10 dB below the S9 value of -73 dBm when I point my beam due South. That is a strong interference. I can also hear the first, second and third harmonics much weaker. The signal is present 24/7. I just finished talking to the Mediacom Cable TV Co. Tech Service and they are going to send a technician with some detection gear. They want to get it fixed because of FCC requirements and also to satisfy the customer. Defective cables is a common problem that the Cable TV and Wideband Internet Companies are interested in. Mediacom Co. here has been a pretty good company to deal with. My Wideband Cable Internet connection has also been very good. Bill W0IYH "Harold E. Johnson" wrote in message news:jOt7e.16798$8Z6.10348@attbi_s21... Is anyone else hearing the harmonics of 3.5795 ? Bill W0IYH Bill, I have a little TV set on a different desk in the shack here, maybe 10-12 feet from the radio. With it on, I still can't hear the 4th harmonic above an "S-0" with the rig on the yagi. If I go to the inverted L, (L matching network tuned to 40 meters) it comes up a little bit to perhaps a "S-1". That represents a level of somewhere around -120 dBm. Maybe less than that remembering the bandwidth I'm using. Apparently my neighbor is still asleep, I do NOT hear the signal to the NorthEast that I had yesterday. It BTW, was no stronger than this one in the shack today. My homebrew Txcvr is a hamband only, so I can't listen to the other harmonics, but even the fundamental at 3579 is only an S-3 on the inverted L (Voltage fed 1/2 wave on 160) with the matching network on 80 meters. That must be some TV set you're listening to. I remember your article on your antenna, but don't remember, are you by any chance using open wire line? Regards W4ZCB |
#12
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I just finished talking to the Mediacom Cable TV Co. Tech Service and they are going to send a technician with some detection gear. They want to get it fixed because of FCC requirements and also to satisfy the customer. Defective cables is a common problem that the Cable TV and Wideband Internet Companies are interested in. Mediacom Co. here has been a pretty good company to deal with. My Wideband Cable Internet connection has also been very good. Yes, so good that I'd cancel them for their outages if it were not so impressive when it IS working. Never thought that they might be sending the color burst frequency down the cable as well as the programming. I've ALWAYS disliked TV programming so much (other than a few exceptions) that I've refused to study the technology. When one of mine breaks it's either to the dump or to some repair shop. Wish you well in getting rid of it. At 14.307, I'd get a nosebleed if I got that high in the band. At 3579, I don't do that mode anymore. (Ernie ALWAYS said, "If God had meant for man to talk with his fingers, She would have put lips on them") Regards W4ZCB |
#13
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The signal on the cable goes to a phase-locked-loop in the TV rcvr. This
keeps the TV picture synchronized. Bill W0IYH "Harold E. Johnson" wrote in message news:I9v7e.14366$Bb3.12702@attbi_s22... I just finished talking to the Mediacom Cable TV Co. Tech Service and they are going to send a technician with some detection gear. They want to get it fixed because of FCC requirements and also to satisfy the customer. Defective cables is a common problem that the Cable TV and Wideband Internet Companies are interested in. Mediacom Co. here has been a pretty good company to deal with. My Wideband Cable Internet connection has also been very good. Yes, so good that I'd cancel them for their outages if it were not so impressive when it IS working. Never thought that they might be sending the color burst frequency down the cable as well as the programming. I've ALWAYS disliked TV programming so much (other than a few exceptions) that I've refused to study the technology. When one of mine breaks it's either to the dump or to some repair shop. Wish you well in getting rid of it. At 14.307, I'd get a nosebleed if I got that high in the band. At 3579, I don't do that mode anymore. (Ernie ALWAYS said, "If God had meant for man to talk with his fingers, She would have put lips on them") Regards W4ZCB |
#14
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William E. Sabin wrote:
The signal on the cable goes to a phase-locked-loop in the TV rcvr. This keeps the TV picture synchronized. I won't say it doesn't happen, but I'd be surprised if your cable operator is transmitting a 14.318 (or 3.579) signal down the cable. (that doesn't mean they don't have a leak that needs fixing!) Roughly 15,700 times a second, a brief burst (about 8-11 cycles) of a 3.579MHz reference signal modulates the TV RF carrier. This burst is used to synchronize the color circuits. Left-to-right and top-to-bottom scanning is synchronized with other pulses that modulate the same carrier. So, for example, on a channel 2 station (RF carrier at 55.25MHz), the synchronizing burst would create a sideband at 55.25 + 3.58 = 58.83MHz. (it would also create a lower sideband around 52MHz but a filter in the transmitter lops off most of the lower sideband, around 54.25MHz.) No 3.58 signal is transmitted. That's how an over-the-air station would work. But cable differs only in that the output of the transmitter is connected to a combiner and then to the cable to your house. (and, of course, the transmitter is a LOT less powerful!) -- Doug Smith W9WI Pleasant View (Nashville), TN EM66 http://www.w9wi.com |
#15
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"William E. Sabin" wrote in message news:cAs7e.16678$8Z6.1255@attbi_s21... Quite right. Thanks. I can hear the fundamental, second and third harmonics as well as 14.317. That last one is S7 on my receiver with my beam pointed South, so it is local in my neighborhood. Is anyone else hearing the harmonics of 3.5795 ? Bill W0IYH Well, that explains why I couldn't hear it. Ours is 4.43361875MHz. Brad VK2QQ |
#16
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You Aussies are always out of tune with the civilized world.
Just kidding, Brad. Thanks. Bill W0IYH "Brad" wrote in message ... "William E. Sabin" wrote in message news:cAs7e.16678$8Z6.1255@attbi_s21... Quite right. Thanks. I can hear the fundamental, second and third harmonics as well as 14.317. That last one is S7 on my receiver with my beam pointed South, so it is local in my neighborhood. Is anyone else hearing the harmonics of 3.5795 ? Bill W0IYH Well, that explains why I couldn't hear it. Ours is 4.43361875MHz. Brad VK2QQ |
#17
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William E. Sabin wrote:
You Aussies are always out of tune with the civilized world. Just kidding, Brad. Thanks. Bill W0IYH "Brad" wrote in message ... "William E. Sabin" wrote in message news:cAs7e.16678$8Z6.1255@attbi_s21... Quite right. Thanks. I can hear the fundamental, second and third harmonics as well as 14.317. That last one is S7 on my receiver with my beam pointed South, so it is local in my neighborhood. Is anyone else hearing the harmonics of 3.5795 ? Bill W0IYH Well, that explains why I couldn't hear it. Ours is 4.43361875MHz. Brad VK2QQ ppffttttttttttttttttttttt :P |