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  #1 (permalink)  
Old 12-19-2009, 5:02 PM
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Default 118.8 tone noise

Alright since I last posted I have concluded that this noise, skip, p25, whatever it is has gotten worse.
I will list my findings, please offer input as you see fit......

Freq affected are :
155.145
153.950
159.200

All these use 118.8 tone

Noise comes in on whichever one it feels like at any given time. I have played with programming and found if I change to 79.7 tone all the noise is gone, however as you know so is communication. I also have removed my antennas from both my handhealds and it still comes over which tells me the source may not be far away. Listening to any and all of the freq listed with NO tones programmed the noise goes away. It appears something is coming in on the tones side of things, not so much freq. Is this possible? We have 2 communication experts on this as well. Something has to give here, our community is suffering from this due to the fact that if any of us want sleep we have to turn our equipment off. It is slightly hard to get tones out to fire/medical calls when your stuff is shut off, but for some of us if we intend to stay married, it has to go. Thank you in advance.
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Old 12-19-2009, 5:13 PM
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Check for 110VAC 60Hz sources of noise from AC power supplies etc. You may be experiencing the second harmonic of 60Hz, that is 120Hz and very close in frequency to the 118.8 Hz you mention.
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Old 12-19-2009, 5:48 PM
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Many years ago I used to have one of those wireless modem extenders that used the house wiring
as a means of getting a phone line in a room where there were no jacks and it used rf frequencies
with pl tones. There was rf all over the spectrum with the same pl tone. When I wrote a letter to the
manufacture of the equipment they responded with a "that's how it works" letter. Needless to say
that I soon trashed this product.
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Old 12-23-2009, 2:12 PM
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If you have a UPS for your computer, check it out as well. I once ran a railroad radio stream and the UPS kicked out spurious emissions over 160-161mhz band, causing my radio to "hang up" on certain frequencies.
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Old 12-23-2009, 8:21 PM
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Reeding your other post and this one, I have a question.

Is this isolated to your radio or are other radio's having the same trouble?
I agree with the others on local intererence, but if this is happening to more the your radio it would not be a local(your house)
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Old 12-24-2009, 10:37 AM
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Turn off each radio one at a time and see if the noise goes away. It sounds like your radios are picking up each others local oscillator and mixing freqs internal to themselves.
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Old 12-27-2009, 6:51 AM
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Quote:
Originally Posted by n4yek View Post
Turn off each radio one at a time and see if the noise goes away. It sounds like your radios are picking up each others local oscillator and mixing freqs internal to themselves.
If it were an LO in a radio there would not be the same PL tone on the many signals rayz379 is hearing.
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Old 12-29-2009, 11:18 AM
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Quote:
Originally Posted by brt View Post
Reeding your other post and this one, I have a question.

Is this isolated to your radio or are other radio's having the same trouble?
I agree with the others on local intererence, but if this is happening to more the your radio it would not be a local(your house)
It is NOT isolated to me. To be exact it is affecting the radios of 4 fire departments in 4 towns. Same noise on all radios. Dispatch is located aprox 1 milefrom my house, but this noise is extending to as far as 20 miles to houses neighboring communities. Is is affecting radios, pagers, and scanners. It can be heard through central dispatch radio and when it happens it luminates the transmit button on dispatch console. It keeps getting worse. Hopefully something will blow up or break soon.
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Old 12-29-2009, 11:23 AM
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I have audio files on my phone of this noise. If I can figure out how to put them on here I will.
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Old 12-29-2009, 11:42 AM
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Suggest to the radio techs. to identify VHF-HI paging transmitter frequencies in the area. Could be a spurious high power paging transmitter. Compare the audio interference experienced on the local government frequencies with paging transmitter frequency audio that are identified.
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Old 01-08-2010, 3:59 PM
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I finally heard some radio traffic in monitor mode on my handheld. The static while in monitor mode is someone talking about trees, cutting this section, that section, sounds like loggers. It has moved to mainly 159.200 and 159.000. Listening to them frequencies with no tones in place I get the loggers?? How can I find out who "they" are???
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Old 01-08-2010, 4:51 PM
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Quote:
Originally Posted by rayz379 View Post
I finally heard some radio traffic in monitor mode on my handheld. The static while in monitor mode is someone talking about trees, cutting this section, that section, sounds like loggers. It has moved to mainly 159.200 and 159.000. Listening to them frequencies with no tones in place I get the loggers?? How can I find out who "they" are???
Who you are hearing may be a co-channel user.

Here's the FCC list of (active and expired) 159.0 mHz FCC Licensees for Ralls County, MO:

KNEB263 JACQUIN, HARVEY 0002536019 IG Active 10/21/2012
KNFU316 ST LOUIS, COUNTY OF 0002511897 PW Active 05/13/2012
WNDL220 GERBER, TERRY L IG Expired 08/21/2005
WNFG790 Stone County of 0005804331 PW Active 02/28/2012
WPBR402 MONROE, COUNTY OF 0002512705 PW Active 02/09/2013
WQFB702 B-K Electric, Inc. 0008816183 IG Active 06/08/2016
WQJD201 TELTRONIC SA 0017876152 YG Expired 08/07/2008
WYC663 RALLS COUNTY AMBULANCE DISTRICT 0002542892 PW Active 01/06/2014
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Old 04-21-2014, 3:14 PM
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kind of bringing back an old thread here but i sort of have the same problem as of recently. Since i have owned my scanner i have had several low band frequencies programmed into my scanner and never had any problems with noise on any of them until about a week ago, 33.74, 33.78 and 33.86 and 46.52 all have an extreme amount of noise, so much that i cant squelch it out even with the squelch maxed out, its bringing up a ctcss tone of 118.8 and it seems to drift from frequency to frequency, sometimes it'll be on 33.74 then it will stop on that frequency and go to another and back and forth and so on. Any ideas to what this may be and can i expect it to go away?
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Old 04-28-2014, 9:08 AM
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Quote:
Originally Posted by fireman3214 View Post
kind of bringing back an old thread here but i sort of have the same problem as of recently. Since i have owned my scanner i have had several low band frequencies programmed into my scanner and never had any problems with noise on any of them until about a week ago, 33.74, 33.78 and 33.86 and 46.52 all have an extreme amount of noise, so much that i cant squelch it out even with the squelch maxed out, its bringing up a ctcss tone of 118.8 and it seems to drift from frequency to frequency, sometimes it'll be on 33.74 then it will stop on that frequency and go to another and back and forth and so on. Any ideas to what this may be and can i expect it to go away?
Like the history of posts indicates, this can be a number of factors, both internal and external. The problem is that 118.8 Hz is so close to the second harmonic of 60 Hz (the frequency of US alternating current) that noise with "AC hum" usually always falses this particular tone. Experienced radio shops avoid using it exactly for that reason.

Possible external sources:
A transmitter which is now in self-oscillation. We don't see a lot of these anymore, mostly with the decrease in tube transmitters, and the decrease in low band usage. What happens is a power amplifier is not properly aligned and goes into oscillation that sweeps up and down the passband. It sounds like a buzzing hum that sweeps up and down. On low band this could be close to you, or far away depending on conditions. Usually seen in the GE PRO series (60s/70s vintage, but still plentiful on low band), but also on high power Micors, especially if someone didn't align it right, or the tubes were going soft. Chances are you won't be able to do anything about it.

Switching power supplies from consumer equipment that should never have been imported because they exceed Part 15 unintentional radiator specs.

Possible internal sources:
Too much current draw on your power supply.

Dried electrolytic capacitors negating filtering and superimposing 120 Hz onto your DC power output (even if your receiver plugs into the wall it has a power supply inside of it). I see this a lot in older equipment, like Icom R-7000 receivers, or older Bearcat scanners.

Bottom line is it's like any RFI. Could be anything until it's isolated.

Good luck. I listen to the 33 MHz fire frequencies a lot, too.
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