continous interference across railband

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timkilbride

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I just moved to a new apartment. I have my 5/8 wave antenna mounted outside the apartment. The radio I am using is a Kenwood TK-790. I am getting continous interference across the whole 160-161mhz rail band. Is there any kind of filter I could put in-line to help this out? I have the squelch set on 15 and still getting interference. I'm using PL-259/SO239 connectors so anything with BNC connections won't work. Thanks for any help.

Tim K.
 

DPD1

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What does it sound like? Is it interference from other transmitters, or more like a power source type of thing?

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KC9JUM

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I am almost going to bet it's a leaky cable system.

One way to tell this.....is to turn on your TV, set it to cable tuning, then hook a set of rabbit ears to the TV. Have the TV do the auto channel scan. If you can see TV channels off the cable it's a leaky cable system. Apartments are infamously known for leaky cable.

Alternatively it might be a neighbors Plasma TV.

Getting it fixed may be a problem..... right or wrong taking such an issue with apartment management is a great way get dumb looks and brushed off.

The TK-790 is -known- for being great at inter mod resistance, so whatever it is is ON FREQUENCY, so I doubt a filter will help much.

If you can, if you have a portable with battery.... turn it to the railband... and cut the main power in your house....if the noise shuts off, it's inside your place.. if not... it's time to Direction Find..

If it's inside, turn things off one by one in your place until you find it.
 
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burner50

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KC9JUM

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Perhaps, but all the same, it has to be on frequency. Check anything you have plugged in, in your house. Hopefully it's not a neighbors gadget... it may be a night mare to get them to do anything about it. Apartments can be RFI nightmares!
 
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burner50

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Perhaps, but all the same, it has to be on frequency. Check anything you have plugged in, in your house. Hopefully it's not a neighbors gadget... it may be a night mare to get them to do anything about it. Apartments can be RFI nightmares!
I've never noticed interference while traveling thru ames.

And if it is the wiring in the house/apartment building, its up to the homeowner/landlord to maintain. If it was not in the house the FCC would have jumped down their throats by now.

As I said before, that is the EXACT chroma carrier for a CATV Distribution system. That one CATV Channel covers the entire rail band and then some. CATV Channels are 6mhz wide.
 

timkilbride

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I am almost going to bet it's a leaky cable system.

<<<<<One way to tell this.....is to turn on your TV, set it to cable tuning, then hook a set of rabbit ears to the TV. Have the TV do the auto channel scan. If you can see TV channels off the cable it's a leaky cable system. Apartments are infamously known for leaky cable.>>>>>

I ran a channel sweep on the "cable" setting with rabbit ears hooked up. The scan came up with two channels, 7 and 12. So does that mean there is a leaky cable system then? Do I contact Mediacom who is the provider here or who do I contact? I personally do not have cable and just use rabbit ears for my TV enjoyment.



<<<<<Alternatively it might be a neighbors Plasma TV.>>>>>

My LCD HDTV does create some interferance, but shutting the blinds knocks the interferance out.

<<<<<Getting it fixed may be a problem..... right or wrong taking such an issue with apartment management is a great way get dumb looks and brushed off.

The TK-790 is -known- for being great at inter mod resistance, so whatever it is is ON FREQUENCY, so I doubt a filter will help much.

<<<<<If you can, if you have a portable with battery.... turn it to the railband... and cut the main power in your house....if the noise shuts off, it's inside your place.. if not... it's time to Direction Find..

If it's inside, turn things off one by one in your place until you find it.>>>>>
I un-plugged everything, it didn't go away. I even changed my 5/8 wave to a 1/4 wave and that made it worst so I went back to the 5/8 wave.

Thanks for the help

Tim K.
 

timkilbride

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Not likely... But easy for you to test tim.

ASSUMING you have Mediacom, Grab your RR radio. Tune to channel 48 on your radio and your TV to channel 20.

That is the exact chroma carrrier for channel 20. Key your mic and see what happens to your picture.

EDIT: My credentials on the subject :
http://www.radioreference.com/forums/showthread.php?t=50642
I don't have any cable at all. I'm in Cedar Rapids now. I tried the channel 20, keying on 48, it didn't do anything to the tv but I didn't have a signal on 20 either.

Tim K.
 

burner50

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I don't have any cable at all. I'm in Cedar Rapids now. I tried the channel 20, keying on 48, it didn't do anything to the tv but I didn't have a signal on 20 either.

Tim K.
ahhh... well I havent had any interference problems thru cedar rapids either...

Theres alot of stuff going on in cedar rapids because of the flooding yet... maybe it has something to do with that?

what else do you have for radios? 440 ham? could test with that...
 

burner50

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Hook up a dipole to a scanner and start searching...

Thats how I did CLI when i worked for the cable co
 

timkilbride

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ahhh... well I havent had any interference problems thru cedar rapids either...

Theres alot of stuff going on in cedar rapids because of the flooding yet... maybe it has something to do with that?

what else do you have for radios? 440 ham? could test with that...
Only other radio I have is a Uniden BC780, that is going to be replaced with a BCD996t when it arrives. No 440 or anything.
 

DPD1

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I un-plugged everything, it didn't go away. I even changed my 5/8 wave to a 1/4 wave and that made it worst so I went back to the 5/8 wave.
That's because that's more wide-band. Again... What does it sound like? Does it go on and off like a transmission? A constant hum? Maybe you can upload a recording.

Dave
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timkilbride

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I shot a video and uploaded it to youtube, I guess that route will work. I have my radio on a priority scan so when the audio cuts out, that is why, it is checking the priority channel. I will post the link when it is done processing.

Tim K.
 

KC9JUM

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What is the link?

I am curious, by chance are you in a two story apartment?

a 1/4 wave has a higher horizontal beam width....... which means you could be picking up something from a neighbor upstairs or downstairs....
 

timkilbride

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What is the link?

I am curious, by chance are you in a two story apartment?

a 1/4 wave has a higher horizontal beam width....... which means you could be picking up something from a neighbor upstairs or downstairs....

I'm on the second story of a two story complex.

Tim K.
 

DPD1

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So the pulsating is from the priority, or it's doing that itself? At any rate, it sounds power related to me. Which unfortunately is going to be hard to track down. And even if you can, it might be something that you can't fix.

Go outside with your handheld and see if you can track it down that way. Use your body to attenuate the signal. If you can get really close then take the antenna off and see if you can get it that way. When you get it that way, you know you're very close. I'd look at any kind of power supplies... Sprinkler timers, stuff like that. It may be something as simple as a really poor power supply on a neighbors device.

If it's the power lines themselves, the city will on rare occasion be willing to take a look at something like that. But it's tough.

Dave
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timkilbride

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So the pulsating is from the priority, or it's doing that itself? At any rate, it sounds power related to me. Which unfortunately is going to be hard to track down. And even if you can, it might be something that you can't fix.

Go outside with your handheld and see if you can track it down that way. Use your body to attenuate the signal. If you can get really close then take the antenna off and see if you can get it that way. When you get it that way, you know you're very close. I'd look at any kind of power supplies... Sprinkler timers, stuff like that. It may be something as simple as a really poor power supply on a neighbors device.

If it's the power lines themselves, the city will on rare occasion be willing to take a look at something like that. But it's tough.

Dave
www.DPDProductions.com
Antennas & Accessories for the RF Professional & Radio Hobbyist
Yes, the pulsating is from the priority channel being checked. I will take my handheld and see what I can come up with.
 

KC9JUM

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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.
 
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