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Author Topic: Best rfi removal gadget  (Read 8071 times)
NB9N
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Posts: 68




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« on: May 02, 2012, 08:20:49 AM »

I have been dealing with an s-7 powerline noise over the past 4 months.  The power company will come out but in case they will not or cannot clean it up does anyone have a silver bullet device that will illiminate this noice?  I do use my NB and it works fairly well but not perfectly due to static crashes etc.   I have thought of dsp audio devices, etc. but want other opinions.

Joel/nb9n
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W2MV
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Posts: 207




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« Reply #1 on: May 02, 2012, 08:36:24 AM »

If your noise is indeed from power lines, then the only "magic bullet" as you say would be to do what you've already done: use your NB.

Our power company here in NY has a guy who comes out with a directional antenna and a commercial wideband receiver from Radar Engineers. He has always been able to locate RFI from the power lines, even sometimes RFI from other sources such as a neon sign or battery charger.
Good luck.
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KD0REQ
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Posts: 972




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« Reply #2 on: May 02, 2012, 11:44:10 AM »

there are several phase/null bridges on the market for this.  MFJ 1025/1026 and NCC-1 from DX Engineering are out there.  you need a sensing antenna that allows you to put the noise out of phase and mix it with the functional antenna.  it's a $160-300 investment that is not plug and play, but hands-on with a bunch of knobs.
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NB9N
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Posts: 68




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« Reply #3 on: May 02, 2012, 12:22:04 PM »

Does "nulling" the rfi (using nb etc.) de-sensitize the front end gain of the radio?
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W5LZ
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Posts: 477




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« Reply #4 on: May 03, 2012, 09:54:17 AM »

The single most absolute sure thing 'thingy' to get rid of power line noise is distance.  After that, it's a matter of finding something that 'works' in you particular case/situation.  An -adjustable- 'noise blanker' tends to work nicely in most cases, but, are not all that common or cheap, and, require adjustments for 'each' noise.  I'm sure they could be made 'automatic', but count on the price to take huge jumps (how do you tell that device what a 'noise' is?).  A loss of sensitivity when using these sort of thingys?  Some, but usually not all that drastic.  And then, what's the alternative??  There are always going to be 'catches' to using devices like this, there's no way around that.  The 'trick' is to find the level of noise suppression that isn't all that much of a problem/compromise.
I'm still looking for one'a them thingys so if you find one that works for you, be sure to tell us about it!
 - 'Doc
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W2MV
Member

Posts: 207




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« Reply #5 on: May 03, 2012, 10:08:17 AM »

I also have tried the ANC-4 phase-canceller. It works under some conditions, i.e., when the local interfering noise is being sufficiently picked up by the "noise" antenna. That's the tricky part.
An MFJ-1026 is sitting on my shelf waiting to be installed and compared to the ANC-4.
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N2QLT
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Posts: 27




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« Reply #6 on: May 07, 2012, 09:10:51 AM »

Trying to "cancel out" power line noise is a pain in the butt. I would get a portable AM radio (like a GE Superadio) with a loopstick antenna. You should be able to walk around and find the source of the noise yourself (cracked insulator, etc). Then, call the power company as many times as needed to get them to fix it.
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WX7G
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Posts: 6136




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« Reply #7 on: May 07, 2012, 03:55:51 PM »

I have been dealing with an s-7 powerline noise over the past 4 months.  The power company will come out but in case they will not or cannot clean it up does anyone have a silver bullet device that will illiminate this noice?  I do use my NB and it works fairly well but not perfectly due to static crashes etc.   I have thought of dsp audio devices, etc. but want other opinions.

Joel/nb9n

Are you sure it is power line noise?
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K4IA
Member

Posts: 66




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« Reply #8 on: May 07, 2012, 04:42:22 PM »

Don't give up on the power company.  Power line noise is an inconvenience for you but for them it represents wasted power (lost money) and the potential for a catastrophic failure in the near future.  They would much rather fix an arcing insulator or bad transformer connection now than deal with a major power outage in a blinding storm later. 

I complained to our local provider, Dominion Virginia, about noise from a transformer in front of my house and they had a crew fix it in a few days. 
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W0FM
Member

Posts: 2056




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« Reply #9 on: May 09, 2012, 02:36:04 PM »

If it is, in fact, power line noise, then the "best RFI removal gadget" is the power company employee in the van with the directional antennas on top.  It's his job to ID the source of the noise and place a service ticket to resolve it.  Don't assume they won't fix it.  It's in their best interest.

I called the power company when I had RFI from the lines near the road and their RFI "Ghostbuster" came to my house.  I took him down to the shack and let him hear it on 40 Meters.  He said "Yep, that's us".  In a few days they had it identified and fixed.

I have his business card taped in my shack near the phone.

Terry, WØFM
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VA2FSQ
Member

Posts: 511




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« Reply #10 on: May 16, 2012, 08:36:04 PM »

Really, the ultimate solution is to move to the country.  Otherwise, you will fix one source this week and then the neighbrhood store will have a sale on plasma tv's and you will always fight.
Get yourself a NCC-1 or the MJF and a noise antenna.I can get rid of just about any noise, down from s9 to s3 on a noisy day on average noise in the neighbourhood to getting rid of high intensity lights that the neigbour (a-hole) two house down installed.  That one give S9+30db, and I get it down to baseline noise levels s3-s7 depedning on the band.  On quite days I have baselines of s1 to s2.
Best add on I bought
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VA2FSQ
W1AEX
Member

Posts: 69


WWW

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« Reply #11 on: May 20, 2012, 09:13:04 AM »

Really, the ultimate solution is to move to the country.  Otherwise, you will fix one source this week and then the neighbrhood store will have a sale on plasma tv's and you will always fight.

Living in an area with good separation between homes does help, but even life in the country can be problematic with electric fences around the pastures and ancient hardware on many of the rotting distribution poles. It really is like a game of whack-a-mole keeping ahead of this stuff. I use an open-wire-feedline center-fed 190' long transmitting antenna for 160/75/60/40 meters and at times it can be quite a noise collector. In addition to getting assistance from the power company now and then, I've resorted to a pair of 85 foot wire loops (bi-directional K9AY triangular shape) for VLF-BCB-160-75-60-40 meter reception. They are quiet and hear signals the transmitting antenna cannot even detect. I've also been looking at the Pixel RF PRO-1B as a possible new defensive toy to thwart the ever-growing number of little buzzes and wandering oscillations during the daytime on 75 meters. It gets very good reviews and several hams I have corresponded with have indicated that it hears very well and is quite effective at improving the SNR on bands plagued with noise. We really are at the mercy of whatever appliances and electronic garbage our neighbors decide to bring home from the shelves of Walmart.

73,

Rob W1AEX
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WB8VLC
Member

Posts: 123




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« Reply #12 on: May 23, 2012, 09:05:26 AM »

Without a doubt the best RFI removal gadget would be to fire everyone at the FCC who isn't a ham and replace them with some hams who have been in the RFI trenches.
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WB8VLC
Member

Posts: 123




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« Reply #13 on: June 05, 2012, 11:58:26 AM »

I'm going to reword this because I was too harsh on the hard working FCC personal overall.

It should say that anyone who isn't an RF Engineer, RF tech or RF knowledgable should not be making any decisions on what can and can not be marketed. 

 The average FCC  engineer has no control over what the average consumer purchases thru foreign web sources, their job is to enforce the bad products out their that we consumers purchase.

Recently talking with some FCC personal I find there are some good knowledgable helpful individuals who are very RF savy at the various field offices throughout the US.

It is the bureaucratic types who need to listen to the RF people at the FCC not the other way around.


Mike

 Also the MFJ1026/1026 boxes do work (the 1026 better), you just need to get a good strong signal on the aux antenna port and take your time with adjustments.
« Last Edit: June 05, 2012, 12:01:14 PM by WB8VLC » Logged
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