It is usually so, but there are also return channels to the headend below 54 MHz in some places.
A loose conector or a broken shield might allow it to leak out. 73, Jose, CO2JA -- John Taylor escribió: > Ron, as a semi direct answer to your question, as a general rule > cable tv frequencies typically are well above hf radio. It is not > impossible for there to be interference, but generally it will be > some other source. One thing to remember with most cable systems is > that the line and trunk amps need to be powered and are usualy done > through the cable itself with pole mounted power supplies every so > often in the system. If there is a connection breakdown somewhere > near you, it"could" cause your symptoms. You did provide a clue to > your own situation. You mentioned a bucket truck in the area when the > noise suddenly stopped and then started again. If he was working at a > particular pole, you might try physically walking to that pole and > see if you hear any arcing, especially if this is also a power pole > carrying primary voltages. It is not uncommon for the insulators to > start breaking down due to dirt and grime in the air getting on the > insulators and forming a path for the current to travel. This > manifests itself frequently as strong intermittant static. > Your noise blanker typically only works on "impulse" noise such as > ignition, etc. > Have you also eliminated all noise sources in your own home, such as > televisions, computers and monitors, etc.? > A great way to chase the source is to take a small portable shortwave > receiver with a small antenna and follow the noise to it's source. > You can usually get very close very quickly with a little leg work. > Just some thoughts .... > Best of Luck > > --- In digitalradio@yahoogroups.com, w4lde <[EMAIL PROTECTED]> wrote: > >> If this question is inappropriate for the reflector I apologize but >> > as > >> of last Friday I started to experience significant noise (S-9) on >> > all > >> bands from 160 through 15M with the lower frequencies much >> > stronger. I > >> thought that it was due to power line noise but it appears to be >> intermittent in that it completely disappeared last Friday evening >> > but > >> once again showed up last Saturday and stayed this way. On the >> > Ft1000mp > >> the noise blankers are completely ineffective. At the same time I >> started having internet problems and the cable company indicated >> > they > >> should have the speed issue fixed by Tuesday. >> >> The cables are run on poles until they enter a subdivision which >> > then > >> run underground. My question is can cable lines be the possible >> > problem > >> to HF frequencies? The power and cable companies have been >> > installing > >> new poles and running new lines in the area which initially led me >> > to > >> believe it was a power issue however, while I was writing this >> > email the > >> noise completely disappeared for a few seconds and then >> > reappeared. As > >> I was looking out my window I noticed a cable company buck truck >> through the woods towards the main road, I am off now to talk to >> > them > >> and see what I can discover. Any suggestions? >> >> Thanks for the bandwidth if this question is inappropriate for this >> reflector. >> >> 73 de >> Ron W4LDE >> >> > > > > ------------------------------------ > > Announce your digital presence via our Interactive Sked Page at > http://www.obriensweb.com/sked > > Yahoo! Groups Links > > > > -- MSc. Ing. José Angel Amador Fundora Profesor Auxiliar Departamento de Telecomunicaciones Facultad de Ing. Eléctrica, CUJAE Calle 114 # 11901 e/119 y 127 Marianao 19390 Ciudad de la Habana, Cuba Tel: (53 7) 266-3445 Mail: amador at electrica.cujae.edu.cu
