Dropped 4 S points of noise

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zl2taw

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I live in a unfriendly RF noise environment, which plays havoc with HF (hence why I have a portable SWL station).
I set up the Kenwood R-5000 and a netbook (digi decoding) on the kitchen table & threw up my squidpole portable antenna, all I saw was the noise level rise and wipe out the entire HF spectrum.
So for a laugh, I thought I would try out my portable battery (only 7Ah), and what I saw I couldn't believe.....The noise floor dropped by at least 4 s points across the entire spectrum.
In fact the noise wasn't an issue until I got 5mHz & below where it peaked to about a S6, before that the noise floor was a constant S9.

Just thought I would share my findings and this might give others hope of listening again
 

majoco

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Does this mean you used the R5000 on it's 12v connection - thereby cutting out the internal power supply?

So either the noise is coming down the mains or out of the internal power supply (which I doubt!). Have you had your mains power earth connection checked? I had a high-ish noise level in one house where I had a flat and found the earth clip on the ground rod was quite loose - a couple of spits and sparks as I tightened it too!

Good luck in your search - hopefully you'll come out with a smile on your face!

Fortunately my noise level doesn't even think about raising the "S" meter. :)
 

SCPD

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Very likely he's getting some kind of noise thru the AC mains. I highly recommend Corcom filters. Buy a cheap power strip for a few bucks and solder a Corcom filter in between the strip and plug. Very easy to do. E-Bay is a great source of them and usually for 50% or more off the retail cost.

I just bought a 10VN1 unit and will be making a new strip soon. It has the best filtering of all of their units: N Series

Here's the one I bought: http://www.ebay.com.au/itm/Tyco-Electronics-Corcom-EMI-filter-Cat-10VN1-NNB-/230291438354
 
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E-Man

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I do not know what is best for noise filtration, but I think Panamax makes good stuff. I use one of these for my Sony LCD and will probably add one to my Shack as well.

Amazon.com: Panamax MFP-400 2 Outlet HD Ready Surge Protect - Black: Electronics

Here are some video's of Panamax Noise Filtering, the first one shows noise from a power supply. The second one shows that the MFP-400 removes the A/C noise that the high dollar unit does.

Panamax Noise Filtering Demo - YouTube

Panamax MFP-400 Over Voltage Demo - YouTube

Here is the company that makes the Noise Sniffer from the video's, their quietline looks like a interesting product.

AudioPrism introduces Ground Control...
 

majoco

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US versions of filters and surge protectors are liable to spit the dummy on Australian 230volts!
 

E-Man

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The one Nick linked should work. Yea you could give up the ghost with the ones I linked sorry.
 
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majoco

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Well, I looked at what they called the "technical specification" on the Amazon site and it didn't mention voltage. Admittedly the Tyco one does say 120/240v - does this mean that you specify what you want? I think that if the device, when fitted into 120v systems, will allow 240v to be applied before anything goes pop in the surge suppressor is not doing it's job very well.
 

SCPD

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Well, I looked at what they called the "technical specification" on the Amazon site and it didn't mention voltage. Admittedly the Tyco one does say 120/240v - does this mean that you specify what you want? I think that if the device, when fitted into 120v systems, will allow 240v to be applied before anything goes pop in the surge suppressor is not doing it's job very well.
Martin, their filters work all over the world. You don't need to specify anything. They support up to 250vdc and between 50-60hz.
 

kb2vxa

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Seems to me the solution is in plain sight, use battery power.

Uh, so where else but the mains and/or AC power supply is the noise coming from? Seems like a bit of misunderstanding the OP there Maj.

Then there's that unusual application of "spit the dummy" that sparked debate I spotted an uh oh in. A 250VDC rating doesn't exclude the possibility of letting the magic smoke out when it's attacked by the 325VAC peak value of the 230VRMS mains. That's a US rating, here the peak value is 162.6 for the 115VRMS nominal mains voltage. If you want to know peak just multiply root mean square by 1.414, it's a sine wave.

Oh just skip all that jumping through hoops and stick with the battery, it works.
 

zl2taw

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thanks for all the feedback, as memtioned by Warren, I think I will stick with the battery
The noise floor was with the mains plugged in, and 12v disconnected. I havent tried both together & dont really plan too.

its a portable setup here, the wife was working, kids were out playing, so it was a spur of the moment thing.
I will look into a filter for a cheap strip & see what comes of that

Take care guys

73 Doug
 

zl2taw

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well I managed to locate a emi filter & grabbed a strip and hardwired it together, it surprised me the result
for spending Australian $15, I got some good results

20mHz before S1 after S0 battery S0 (noise in S points on the R-5000)
15mHz before S3 after S1 battery S0
10mHz before S2 after S1 battery S0
5 mHz before S8 after S7 battery S7
2.5mHz before 10db/9 after S8 battery S7

pretty happy with the results
 

prcguy

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Grounding has nothing to do with good SWL reception and noise reduction and can actually increase received noise.

I've experienced this countless times with end fed wire antennas grounded to towers and verticals grounded to the house main ground and grounding coax from dipoles entering the house. Any common mode noise on your AC ground from computers, monitors and any other switching power supply in your house can travel along the shield of the coax to the antenna and be picked up at very strong levels.

Within the same house with the same high noise floor I can string up a dipole over the house fed with TV twinlead or 450ohm ladder line right to the same radio without grounding it and the noise floor drops drastically.

In the case above I use a 1:1 choke balun at the radio or antenna tuner and the radio is still running from a power supply plugged in with a 3 prong grounded line cord, so the radio is technically grounded but I've severed the common mode path for noise gunge traveling up the grounded feedline to the antenna.

I also ran an SGC autotuner for years at the top of a well grounded tower feeding a 100ft random horizontal wire and every time I transmitted on HF with 100w my DSL Internet would blank out for several minutes. I've since changed my main HF antenna to a G5RV in the exact same spot as the 100ft wire from the autotuner but have not grounded the feedline and my noise floor dropped considerably and I can run 1500w with no effect to the DSL line.

I spent some time with EZNEC modeling the SGC tuner, 100ft wire and all the dimensions of my tower, ground straps, feedlines and 50ft of aluminum cable tray grounded to the tower and found the tower and ground system radiated almost as much current as the main 100ft antenna wire.

Every antenna has two halves and RF currents will try to flow equally on both halves with one being the coax shield on an unbalanced antenna. Ground that shield to your house AC mains and you potentially bring your antenna right into the house and plug it into every noise generator in the house.

Every antenna installation, ground system and house is different and some people luck out and don't cause a noise problem but many do. Before giving up on noise, float your antenna above ground to see if the grounding is causing noise ingress then deal with it appropriately depending on your lightning ground needs.
prcguy


What are you using for grounding??? Proper grounding is essential to a good SWL set up.
 

ridgescan

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prcguy- a #12 awg wire from the sw antenna switch here in the room to the cold water pipe RAISED noise 1/2 s-unit at LW, but LOWERED noise 2 full s-units at MW, RAISED noise 1/2 s-unit at 4.5 megs, but LOWERED noise a full s-unit at 2.5, 3.5, 10.5,-1/2 s-unit at 11.5, 12.5,-again 1 full s-unit at 17.5, 18.5 megs. NO noise floor change at 5.5, 7-8-9-13-14-15-16-and 20^up, and completely eliminated the high buzz from my computer modem across the bands.
I also have the antenna tripod on the roof grounded to the fire escape system of my building which is bolted to the I-beam building frame. That ground eliminated an "electrocution" type buzz but I am not sure how that registered on the meter. I will do that today.
It does make a difference in my case here.
 

majoco

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Unfortunately the regulations in the US say that all earth systems have to be bonded together - therefore any earth rod you intend to use to ground your antenna and/or equipment will also carry any earth interference right into your radio. I don't give a rats backside about that - I have a separate ground rod and a sort of earth mat that is only connected to my radios - there is no connection to the house power ground - only phase and neutral - and every unit has an isolating power transformer, whether it be for 12volts or internal to the radio. The result - very little locally generated noise. :)
 

Sol100

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A Black Art.

Noise reduction is a bit of a black art and I don’t think there is one universal answer.
In Australia and New Zealand we use an MEN system of earthing where the neutral link and the earth link are bridged together. The idea is to compensate for the extremely poor ground conductivity (hi resistivity) in many places through out the regions. Even an earth rod bonded to the water system can have an extremely high ground resistance which is not good in a fault situation.
One can imagine the potential noise on this sort of system especially now that all sorts of RF is now imposed by a plethora of services and devices.
Earthing the radio’s or indeed the ant from the house grounding system for me was a disaster noise wise. What I found the best method of noise control on the HF bands was to use a 9:1 balun separately earthed and fed by floating 50 ohm coax. Also I found a ratio 15 to 5 gave the best coverage across the bands.
As a final thought some people swear by using common mode chokes, wrapping the coax thought a ferrit torroid a number of times close to the receiver may well improve things even more.
If you can find the room give it a go.
See attachment.
 

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nanZor

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I would also look at the common mode choke the squidpole is using. I found one reference for the squidpole and saw this reactive coax-choke:

http://nerc.vk5bbs.ampr.org/pages/techdata/imagetd/Slide14.gif

With those dimensions, I'm not sure it is really doing the job you want it to. While I'm a fan of HF-mix ferrites, a real handy chart for determining the choking impedance of the coax-wound choke comes from:

Common-mode chokes

Perhaps something along these lines might be worth trying as well. Don't feel bad - I run my gear solar-powered because of common mode noise issues. (Not directly, but charging a 55ah AGM deep-cycle every so often and running from that...)
 
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woebbers

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Very likely he's getting some kind of noise thru the AC mains. I highly recommend Corcom filters. Buy a cheap power strip for a few bucks and solder a Corcom filter in between the strip and plug. Very easy to do. E-Bay is a great source of them and usually for 50% or more off the retail cost.

I just bought a 10VN1 unit and will be making a new strip soon. It has the best filtering of all of their units: N Series

Here's the one I bought: Tyco Electronics/ Corcom EMI filter, Cat# 10VN1, NNB! | eBay
Nick,

Just bought one...looks like a simple line in and line out filter..I know im getting some noise back thru the power strips..I'll let you know how it works

thanks
Sal
 

majoco

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I'm using the same system as Sol except my antenna is an OCFD fed into the primary - no ground. I tried many variations on the turns and found 30 primary and 10 secondary worked best to give a flat frequency response from 2 to 20MHz which then rolls off to 30MHz. I guess the ferrite toroid is the wrong mix for the upper frequencies but I don't listen up there on that antenna.
 
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