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Author Topic: 6 meters useless  (Read 905 times)
WB8PFZ
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Posts: 81




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« on: May 25, 2008, 10:32:50 AM »

I put up my 6 meter beam. I have a S9 S20 over noise level. I look on my spectrum analyzer and see a signal from 50.1 thru 64.0 . What am I seeing and hearing? There are cable lines 100 foot away. Any ideas? Thanks Mike
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WA7NCL
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Posts: 625




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« Reply #1 on: May 27, 2008, 08:10:55 AM »

Swing the beam and try to get a bearing on it.  Then start looking in that direction.

If it doesn't seem to be directional, it might be in your own house.  Turn all the power off to the house and see if it is still there.  (you need a battery for the rig).  Then if it goes away, turn one breaker on at a time and see if it reappears.  If it does, figure out what is running off that breaker.

I have found RFI sources in home are:  Wall wart power supplies, computer equiment (including routers etc), new digital TV sets.

If you have some sort of portable radio that tunes near 6m (say TV band and you don't have Ch2 in your area), you can go searching for it.

Good luck!
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W8IXY
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Posts: 9




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« Reply #2 on: June 02, 2008, 01:45:11 PM »

I see your QTH is in Cleveland.  What you may be picking up that blankets much of 6 meters, and frequencies from 50.1 mHz to 64 mHz, may be the digital signal from WKYC-TV.  WKYC-TV runs their analog on channel 3, with their digital channel on channel two.  Channel two runs from 54 to 60 mHz, and channel 3 runs from 60 to 66 mhz.  I live less than two miles from their tower, and it is almost impossible to hear anything on 6 meters at my location.  Digital is inherently VERY wideband (along with several methods to include additional channels inside the 54-60 mHz channel)  Even if the out of channel products are 70+db down, that still allows for a little bit of "hash" outside the allocated channel.  WKYC is running about 10kw ERP on channel two, with their antenna over 900 feet above average terrain.  Interference should end on February 17, 2009, when WKYC abandons both VHF channels and commences broadcast DTV on UHF TV channel 17, which isn't too far from 500 mHz.  

73
Ted
W8IXY
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WB8PFZ
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Posts: 81




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« Reply #3 on: June 02, 2008, 02:19:30 PM »

Thanks For the reply Ted. Kinda what others told me. Anything we can do to operate now? Any kind of filter? Mike
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N6HPX
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« Reply #4 on: June 02, 2008, 03:44:59 PM »

You could do the last item first by turning off items in the house,how far away is your computer from the radio and does it do this while its turned on. Are there florences or many other rf devices around.

Just do a simple test and again also see how and what direction that TV station is from you.
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WB8PFZ
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Posts: 81




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« Reply #5 on: June 02, 2008, 04:39:47 PM »

It is not in the house. Did all those checks. I am very close to the TV transmitter. Seams odd that someone could have that WIDE of a signal and be LEGAL. Mike
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W8IXY
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Posts: 9




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« Reply #6 on: June 03, 2008, 01:17:57 PM »

Hello Mike,

Theres not much you can do right now.  You can't filter out something thats being radiated on-frequency.  About the closest thing you CAN do is use a directional antenna, beam, or otherwise, and hope that the station(s) you want to contact do not lie in the azimuth from your antenna to WKYC's tower, trying to place the radiated signal from their tower in as deep a side null in the beam as you can get.  At 6 meters, its also probably not practical to try to install a "noise antenna", and use a phasing system to eliminate noise from a certain direction, but YMMV.  Knowing the engineers at WKYC, they are certainly not exceeding any out of band supression requirements.  They have one of the best engineered stations in the market.  I look at it this way....at my age, .....February 17,2009 will be here in a blink of an eye.

73
Ted W8IXY
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