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Scantenna question

A

ALRocker

Guest
I just had a new Scantenna installed. It's 35 feet up. The problem is it picks up so much electrical noise, that it wipes out the weaker signals. The noise usually is not there early in the AM or in the late PM. Is there any thing I might do to cut this noise out without cutting reception? I have a 50 foot run of RG-6 and I need all of it. I had a discone that got destroyed in a storm and it didn't pick up all the noise. Thanks.
 
My Scantenna is sitting on a two-story rooftop (about 25 feet AGL), running about 50' of RG-6 and is virtually noise free. There is no overhead electric in my neighborhood but the antenna is almost directly above my electric service box.

I'm guessing your coax may be leaky or the Scantenna is just a lot more sensitive than the discone.
 
You might want to post this on the Engineering board. In any case you might want to add a description of the noise (hiss, hum, crackling) to the post plus a closer description of the peak times of the noise. Also, is it frequency dependent.
 
Thanks for the replies. The peak time for the noise is around 8am to 6pm (in other words all day). The noise is similar to what you hear on the air band (AM noise), I think it has to be from power lines, but again it goes away at night and early morning, to a certain degree. The freqs. involved are VHF-hi, since that is about all that is used around here. The only UHFs are local and are not affected. Most everything is on 154-156Mhz. and 158.73 to 160Mhz.
 
So it is not hum. That leaves out TV's and power sources in the house. By the description I would believe 'crackle'. That, unfortunately could mean a lot of things. Since there is a discrete time involved (daylight), depending where you are, it could be a heating problem (expansion) or a drying problem (sun dries off) or wind (typically higher in daylight). Since there was a storm it could be that the local power company has a cracked insulator or dirt/dust on their power transformer (nearby). Try an AM portable tuned between stations to see if it is picking up the same thing. That will help isolate between your system and an external. If it is external then you can use the portable to track it down.

If is is your system, there are a number of causes, water in the coax (dries when the sun comes up), loose connection at either end, kink in the coax (breaks the center conductor). If you have another antenna (a TV antenna on the roof will work for the test) try connecting the scanner up to that and see if it makes a difference in the noise. If it does than I would suspect the coax or the connectors.

If you have a different scanner try hooking that up to scanner antenna to see what happens. It is one of four things:
Scanner antenna, coax, scanner, external interference.
 
I went through that with the ham gear. I would contact the power company. They usually will try to help, but it may take several calls. Could be a cracked insulator, micro-arching, etc. You must see a load increase in the morning.
 
I had a humming problem with my first computerized LED bearcat portable scanner in the late 70's It would only happen in mainly the summer months when eveybody's air conditioning was on. On non -humid days, it would stop. and there was no humming at all in the winter months. I think it could be a generator line that your scanner is picking up, especially if you moved it to another wall socket in the house. And the humming starts right at the beginning of the transmission. And stops at the end while it scans another channel. The above reasons are logical as well.
 
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