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Author Topic: What is this tone I keep hearing?  (Read 4282 times)
W9KDX
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Posts: 770




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« on: July 04, 2012, 11:04:14 AM »

I have been hearing this all over 15 and 17 at regular intervals.  A very rapid (360 cycles per min) repeating tone.  Right now it is on 21.309, 21.302, 21.296.300, 21.291.200 etc, also on 17 right now.  It seems to strike bands randomly and quite often people will transmit right on the frequency.  Some days it is gone, then right back again.  Any ideas?

Thanks
« Last Edit: July 04, 2012, 11:06:58 AM by W9KDX » Logged

Sam
W9KDX
N4CR
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Posts: 1655




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« Reply #1 on: July 04, 2012, 11:14:10 AM »

Probably local interference.

Have you tried running your radio from a battery and turning off all the breakers in your house. It can be an interesting experience to find out something you've been wondering about disappears when you do this. Then you can turn on one breaker at a time and track it down.
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73 de N4CR, Phil

We are Coulomb of Borg. Resistance is futile. Voltage, on the other hand, has potential.
WB6BYU
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Posts: 13038




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« Reply #2 on: July 04, 2012, 12:15:21 PM »

360 cycles/minute is 60 Hz, the AC power frequency.  That should raise some suspicions.

A likely cause is a switching power supply, quite possibly in a newer "wall-wart" of
some sort.  Could also be in a TV or other device that turns on by remote control -
that means it isn't fully off unless it is unplugged.  I've had similar interference from
battery chargers that continued when the power was unplugged if the device was
still attached to the battery.

There are other possibilities, of course, but the most likely explanation is that it
is electrical interference from a source very close to your antenna - quite possibly
in your own home.  That's why the standard approach of running the rig from a
battery and shutting off the main breaker to the house is usually recommended -
if the interference goes away, then check each circuit breaker in turn to narrow
it down to a particular circuit.  From there you just have to check everything
plugged into that circuit to find the source, or go sniffing with a portable
receiver to find where the signal is strongest.
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W9KDX
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Posts: 770




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« Reply #3 on: July 04, 2012, 02:03:26 PM »

Thanks for the ideas.  I was thinking local.  Now comes the fun.  The DX5000 has its own power and I have no wall warts plugged in and nothing electrical close to the house, but something will develop
« Last Edit: July 04, 2012, 02:05:34 PM by W9KDX » Logged

Sam
W9KDX
W9KDX
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Posts: 770




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« Reply #4 on: July 04, 2012, 03:06:59 PM »

Well it's nothing in my house; I didn't think it was as I run a pretty clean shop.

Nearest neighbor is 50-60 feet from my antenna and the nearest utility pole is 4 times that.  Ant suggestions or is this just the price I pay to live in the suburbs?

Thanks
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Sam
W9KDX
KE3WD
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Posts: 5694




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« Reply #5 on: July 04, 2012, 04:21:01 PM »

See if you can pick it up on a cheap AM transistor radio. 

If you can, use the little radio's built in loopstick antenna, walkabout and see if you can pinpoint the place where the noise emanates. 


73
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K0CBA
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Posts: 295




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« Reply #6 on: July 04, 2012, 09:33:28 PM »

The possibilities are almost endless since the FCC relaxed the part 15 incidental radiator emission limits and does nothing to enforce what little protection we have left, but to offer a few ideas;

1) Do you or any one close have AT&T U-verse? ...or their new 'wireless' U-verse?   The AT&T (Chinese junk) is well known to put out garbage from DC to daylight.

2) Plasma TVs? They are crap flingers for sure.

3) Light dimmers.

4) A long shot but fish tank heaters.

Gud luk es 73,

Bob
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KA4POL
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Posts: 1924




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« Reply #7 on: July 04, 2012, 09:54:07 PM »

 A very rapid (360 cycles per min) repeating tone.  
Could you explain what you actually mean by that. What is the tone frequency and what is the repeat frequency of the tone?
If this is a single frequency tone then it won't be a switching powerupply. I'd start by switching off all circuit brakers in the house. Check them one by one to see the resulting effects. How do you arrive at your statement it would be nothing in the house?
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N2EY
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Posts: 3860




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« Reply #8 on: July 05, 2012, 11:26:47 AM »

360 cycles/minute is 60 Hz, the AC power frequency.

No it isn't.

360 cycles/min is 6 Hz. 3600 cycles per minute is 60 Hz.

73 de Jim, N2EY
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WB6BYU
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Posts: 13038




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« Reply #9 on: July 05, 2012, 11:48:20 AM »

You mean your minutes don't have 6 seconds in them???

Yes, we all slip up occasionally.  Sorry about that.
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W9KDX
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Posts: 770




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« Reply #10 on: July 05, 2012, 01:20:08 PM »

 A very rapid (360 cycles per min) repeating tone.  
Could you explain what you actually mean by that. What is the tone frequency and what is the repeat frequency of the tone?
If this is a single frequency tone then it won't be a switching powerupply. I'd start by switching off all circuit brakers in the house. Check them one by one to see the resulting effects. How do you arrive at your statement it would be nothing in the house?

It is best described as a constant pitch tone interrupted very evenly so that the number of tones I can count are somewhere between 300-360 in a minute.  Picture a key sending off a very regular series of dits at about 300-360 in a minute; never stops, never varies, never changes pitch.

Also, I have checked around the house with a 45 year old AM transistor and I get nothing.  I also checked with a portable SW on the exact frequencies that I hear on the base unit and hear nothing.  I am guessing the portable has too small an antenna; I can hear ham transmissions though.

Thanks for all the effort.  It is not the worst interference in the world, just annoying and odd.
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Sam
W9KDX
N6AJR
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Posts: 9891




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« Reply #11 on: July 05, 2012, 01:55:44 PM »

some radios have "birdies" in them , they make tones here and there and are an artifact of the radio. do a google on the radio's name and  birdies and see what you find.  just a thought.
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W0BTU
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Posts: 1577


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« Reply #12 on: July 05, 2012, 02:00:19 PM »

some radios have "birdies" in them

True, but a birdie is a constant, unvarying 'signal' that is present even with the antenna disconnected.  Not what the OP is describing.
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KE3WD
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Posts: 5694




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« Reply #13 on: July 05, 2012, 02:47:37 PM »

It is best described as a constant pitch tone interrupted very evenly so that the number of tones I can count are somewhere between 300-360 in a minute.  ...

Can you give us any idea as to what audible frequency that tone is? 

Even if you can't nail it in Hz, describe it.  High pitched?  Low tone? 

Can you make a digital recording of it, mp3 or .wav or AIFF format, upload that somewhere and provide a link such that others could hear and perhaps even apply some analysis? 


73
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KA4POL
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Posts: 1924




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« Reply #14 on: July 05, 2012, 10:15:08 PM »

So now we are getting closer to the tone. It seems to be some kind of CW like transmission. On VLF for example there are data transmissions for remote control of power. If you got a scope then I'd check it out there to see if there really is a constant length.
Can you rotate your antenna to find a certain direction?
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