continous interference across railband

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timkilbride

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Power Line noise is primarily an AM signal.........

I am almost willing to be that it's a noisy power supply......... and I fear it's a neighbors gadget...or a computer....plasma TV.... it's going to be a NIGHTMARE to get these types to even understand, let alone turn off one their treasured stupid gadgets. Here is a list of some of the stuff.....

Plasma TVs are NASTY noise sources.... avoid them....

I once had a HP scanner that when on made a nasty birdie on 224.98mhz

I have seen some SUPER NASTY birdies from cheap ethernet cables.. this is an easy fix. Just give them a free shielded Ethernet cable.

Plastic computer cases with gimmicky windows. Plastic does not stop RFI. Metal computer cases are great at keeping RFI in the computer.

It could be anything......... I once saw a electric toothbrush make some nasty RFI.

My XYL complains sometimes.....but RFI making gadgets are -not- allowed.... in the house... anything we buy gets a good going over with an HT before purchase.

You could try get that 5/8 wave up higher and get the horizontal lobe away from the noise source.

I can't go much higher. He is my posting I had a couple days ago:

http://www.radioreference.com/forums/showthread.php?t=113274

There is a picture of my setup.

Tim K.
 

KC0QNB

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If you don't have any luck, try this, I am not familiar with your gear, don't want to take time reading manuals, does your handheld have a attenuator?, a RX meter of some kind?
it was mentioned to use your body as a "reflector". Now then program in 135.00MHz am, yes am (the top end of the aircraft band) there is usually nothing there usually real quiet. a some commercial rfi detectors use this frequency. Take a walk around the apartment, squelch open, turn off the priority all you want is good clean noise. If the signal gets strong turn up the attenuator, if you have one otherwise turn tour back to the noise source if it fades twist left and twist right, if it gets strong again take the antenna off of the radio try to pinpoint the noise, if it is coming from inter apartment wall, and you checked a few times to be sure talk to that neighbor, and ask if you can do a walk through with your radio, again trying to pinpoint the noise source if it is an electronic device ask the owner to turn it off and see if the noise goes away. You have to trust me on this one, I have been there done that. let us know what happens, pm me for more details on the search technique. Just another thought, do a recording with the priority OFF do about 30 seconds to a minute of a wav file of the noise and email it to me. I will run the audio through a piece of software I have to analyze audio. I will pm the email address to you.
 
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burner50

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It does sound like power, but the majority of major electrical noise (transmission lines) is in the 60-70 mhz area
 

KC0QNB

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It is hard to tell with the priority on, constant is better, it is power related I agree.
Burner I am curious. 60-70 MHz, unless it is a harmonic, I guess I can't see where you came up with those frequencies, I guess I never looked there for noise, be interesting to find out why there.
 

burner50

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It is hard to tell with the priority on, constant is better, it is power related I agree.
Burner I am curious. 60-70 MHz, unless it is a harmonic, I guess I can't see where you came up with those frequencies, I guess I never looked there for noise, be interesting to find out why there.
eh, I was wrong... its more like 70-80mhz...


with poorly shielded cable you will get interference from electrical from 60-90mhz in your home, and the same interference causes speckles around the visual carrier for OTA Channel 5 on 77.25mhz


Just little things you learn as a cable guy ;)
 

KC9JUM

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I am going to bet it's a wall wart.... electronic device... or something like that with a poorly designed power supply.
 

KC0QNB

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I am going to bet it's a wall wart.... electronic device... or something like that with a poorly designed power supply.
Yeah there are some switching type wall-warts available I have one here I bought it at walmart, so far it seems clean. I think I have hear that sound before, or something very similar, can't be sure though, with the priority check running.
 
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Tim, do you happen to be living near FM Broadcast towers? When the humidity is wayyyy up here in Omaha, I will get "splatter" and spurious emissions from a couple of FM stations over BNSF AAR Ch 6666 and UP AAR Ch 7171.

Sometimes the sound of the spurs will sound very similiar to the audio clip you have posted.
 

timkilbride

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Tim, do you happen to be living near FM Broadcast towers? When the humidity is wayyyy up here in Omaha, I will get "splatter" and spurious emissions from a couple of FM stations over BNSF AAR Ch 6666 and UP AAR Ch 7171.

Sometimes the sound of the spurs will sound very similiar to the audio clip you have posted.
I don't think there is any FM towers around here. My scanner has no problems at all in the 151-158mhz range that it is scanning.
 

KC0QNB

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Tim capture image sent, check your email you are right it just like white noise, any luck locating the source yet?
 

timkilbride

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I sent you a email back. No luck on locating a source yet. I almost wonder if my radio isn't part of the problem? I changed the SQL level from 10 to 15, and it will still hang up after receiving something. Sometimes it will only hang up for 5-10 seconds, other times it will stay hung up until I take it off scan and put it back on, then to only hang up again after receiving something.

Tim K.
 

KC9JUM

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10 squelch on a TK-790... your loosing a lot of signals..... but it's not your radio......something is raising the noise floor drastically.

I am going to now bet this is a someones computer....... I had a PC in a plastic case that made white noise like this on my Kenwood TK-705D. It went away when I transferred the PC guts into a metal case.

If you have the ability to program the radio, the Kenwood radios have a per frequency "beat shift" etc....... it's an option that changes internal radio frequencies that might be mixing with an external noise source
 
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KC0QNB

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I listened to the sample he sent me I may agree it is a computer power supply but my supply emits at a much lower frequency like >25mHz.
Find a 2-3" piece of wire that is the same size as the BNC center pin, stick in the antenna socket and go hunting. The only to eliminate the noise source is to find it first, then see what what happens next.
See it there is a fox hunting (Radio Direction Finding) group close by, check the local ham clubs, hams hate interference and some are very good at finding the problem.
 
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timkilbride

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I listened to the sample he sent me I may agree it is a computer power supply but my supply emits at a much lower frequency like >25mHz.
Find a 2-3" piece of wire that is the same size as the BNC center pin, stick in the antenna socket and go hunting. The only to eliminate the noise source is to find it first, then see what what happens next.
See it there is a fox hunting (Radio Direction Finding) group close by, check the local ham clubs, hams hate interference and some are very good at finding the problem.
I don't have a handheld scanner. I'm not hearing the sounds(interference) I used to when I first started this thread. Right now the radio is just hanging up on white noise after a transmission. Whether the squlech level is at 15 or 5, it still receives the same. When I get a real weak signal, I will change the SQL level from 5 to 15 during the transmission and it will still hang onto the signal. I wonder if someone before me didn't tweak the radio? I have a Motorola Spectra at my dads, next time I go visit him I will bring it back with me and see if I have the same problems with the spectra.

I also put the TK-790 on the programmer this morning. There is not a option for the beat shift. I did take the priority scan off and for some reason it seems to have helped it a little. Maybe the radio its self is causing its own problems?

Tim K.
 

KC9JUM

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Let me look at my Kenwood KPG-44D software.... there is a internal frequency shift.

it may be a global option.... I may be thinking of the TK-5710. The newer version of the TK-790

-edit-
I found the option, you have to click the Ch Edit button on the bottom of the spreadsheet on the KPG-44D windows software to find the option. It's called beat shift and it's a per channel option.
 
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