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HV line and LED/SOLAR noise canceler




 
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December 13, 2018, 06:09:37 PM *
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Author Topic: HV line and LED/SOLAR noise canceler  (Read 1081 times)
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PA0NVD
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Nico and Chappie (Chappie is the dog...)


« on: October 11, 2018, 01:52:09 PM »

Perhaps an old story, but here again some experiences. I live in Costa Rica, about 100 meters from the HV lines looking north-west. When I beam that direction for Europe, I have between S6 and S8 noise from the lines (depending upon the wheather) wich makes life a little difficult (for me anyway, I am from Europe and like to talk to old friends overthere)
So I looked for a solution and stumbled across the website of VK3XU. He did have good results with a noise canceler system, so I tried as well. I did build the canceler described here   http://users.tpg.com.au/ldbutler/NoiseCancelling.htm with a small change, I did couple the noise antenna with a 4 turns link to L1. It took me 1 day
The coils L1 and L2 are 9 mm formers with adjustable core each with 20 turns 0,25 mm wire set 12 mm apart. Using a 2 x 470 pF variable cap from an old radio, I tune 80, 40, 20 and 17 meters
I did put a whip antenna of approx 2 1/2 meters at 60 meters from the HV lines at the fence as a noise antenna. The whip is connected via 50 meters RG58 which I will change for TV coax later. My main antenna is a Moxon for 14 MHz at 6 meters altitude approx 100 meters distance from the HV lines.
After connecting I noticed that there was not sufficient noise gain and I did put a base coil in the whip.
Results...
Unbelievable. I just turn the noise off !!  Grin. Signals  that were absolutely unreadable, come in very clearly now and are completely Q5
The circuit is really simple. The only critical part may be the J Fet. Some FETs like to oscillate. I use now a 2N4393. I did build dead bug at a non-etched print board in order to have a perfect ground. I did put some shield around the two coils to prevent coupling with L3 in the drain of the FET.
Problems with nearby RFI from HV lines , Solar systems of LED lights? this may be you low cost solution without killing the neighbors with the panels and lights!!
Thanks VK3XU, great work and very good info
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WBear2GCR
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Brrrr- it's cold in the shack! Fire up the BIG RIG


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« Reply #1 on: October 11, 2018, 06:21:51 PM »

Is this essentially the basis for the MFJ and some other noise cancelling boxes?

Glad it worked for you with the local line noise!
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_-_- bear WB2GCR                   http://www.bearlabs.com
PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #2 on: October 11, 2018, 08:00:31 PM »

I think it is, I don't really know the diagram of other boxes. But what I saw they all have a phase and level control, so similar.
But it is indeed a marvelous solution. Normally when it rains I get s8 - s9 noise, now i just cancel it.
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WA2SQQ
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« Reply #3 on: October 12, 2018, 09:12:44 AM »

I'm interested in building this. Wondering if you have any photos showing your mods and area around L1? Any audio recordings showing how effective it is?
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PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #4 on: October 12, 2018, 03:26:07 PM »

Hi Bob
It was nice to talk to you over the radio!! I hope we meet again and in future with AM
I will make some pics and post.
Regards
Nico
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PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #5 on: October 12, 2018, 06:45:03 PM »

Here a few pics of the noise canceler
Don't be scared for the rubbish below the little trim pot, it all shouldn't be there. It is a small 15 dB amplifier to test if I can amplify the noise a little more because my noise pick-up antenna was very small. Now I have a 2 1/2 whip and the gain of this circuit was lowered to a few dB only and can be missed.
I like to try a very small active whip antenna from PA0RDT because I noticed that there are many resonances and the phase / amplitude of the noise antenna changes very much when one tune to an other frequency. This because the simple whip antenna is a very bad match to the cable and one like a noise antenna that works for all bands.  The PA0RDT mniwhip is wideband from longwave to 30 MHz and is a good match to the cable. The SDR receiver in the Netherlands from the Twente university uses this antenna
The info for the miniwhip can be found googeling - PA0RDT miniwhip antenna -
Attached the diagram


* noise2_opt.jpg (54.39 KB, 400x300 - viewed 108 times.)

* PA0RDT miniwhip.PNG (16.14 KB, 329x215 - viewed 131 times.)
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WU2D
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CW is just a narrower version of AM


« Reply #6 on: October 13, 2018, 10:30:11 PM »

I did experiments on noise cancellation and published the equivalent tube circuit in ER. I had an arcing street lamp. Feb. 2014, Electric Radio Noise Cancellation by Phasing.
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These are the good old days of AM
PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #7 on: October 13, 2018, 10:37:34 PM »

That's interesting, a noise canceler that glows in the dark!!
If you have a diagram, please be so kind to publish again here. When my shack is ready, may be a nice project to enjoy
Today I did use the PA0RDT active mini whip as a noise antenna and it works very nice. Better than the whip because it matches the impedance of the cable.
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WU2D
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CW is just a narrower version of AM


« Reply #8 on: October 14, 2018, 09:53:48 PM »

As Published in ER. In addition to cancelling noise, this circuit will act as a preselector for the front end of a receiver. Again, I suggest you read the Electric radio article for the explanation of the circuit.


* NoiseEliminator5.jpg (1063.92 KB, 4099x3348 - viewed 105 times.)
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These are the good old days of AM
PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #9 on: October 15, 2018, 12:11:05 AM »

Thanks for the diagram. I like the way of summing noise and signal in the double triode. The diagram is clear and needs no explication.
Perhaps I will experiment a little with active summing instead of the ring core. Interesting!!
I tried the active mini whip as noise antenna. Works excellent. No more noise volume changes if I change frequency and very small, easy to mount.
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WA2SQQ
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« Reply #10 on: October 15, 2018, 08:10:23 AM »

Nico, likewise it was nice having the short contact. Great signal up here in New Jersey. This is one of my winter projects - I just have to get the toroid cores.
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PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #11 on: October 15, 2018, 09:34:54 AM »

Hi Bob
The toroids can be small, I use 15 mm toroids. Because it are transmission line transformers (twisted line), you can use hi-mu ferrite suitable for lower frequencies.
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WA2AAE
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« Reply #12 on: October 17, 2018, 08:05:46 AM »

I had noise problems also and found a kit by VK5TM. I bought only the PCB from him since my junk box had most of the parts described on his web page. It does work and helps get rid of an intermittent noise I had here.

Before building this canceller, I had the noise expert from the local power company come to my home. He had a noise measuring receiver with a built in scope, and when he measured the noise he identified it as from a rooftop solar system. We have lots of them around here. Shortly after his visit and my building the noise canceller, the noise seems to have gone away. I don't know if there was a problem that was repaired, but I hope it stays away.
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Harvey
PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #13 on: October 17, 2018, 05:27:15 PM »

You were lucky that it went away. I am afraid that the HV line doesn't, but the noise canceler take completely care of that...
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