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Any Ideas for Getting rid of MW and HF household Interference

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Joined
Jul 4, 2013
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22
Location
Jacksonville, FL
#1
Howdy and good morning. New to the forum but not to the hobby. Recently dug up my old radios (Panasonic RF 2200; Radio Shack DX 440 and Sony ICF 2010) and being fortunate enough to have a large backyard in the woods backed by a saltwater marsh put up an end fed Grove flex tenna with about 100 ft of shielded coax to shield from all the household interference. The wire antenna is grounded in moist soil with one radioshack grounding rod. (Boy do I long for the days when you could listen on HF with no computer hash!). My problem is my Comcast wifi router and my Direct TV amp located in the same room as my radio. Can't move the radios to another room so my temporary solution is to switch off these too hash generators when I need to dig out a weak station.:)

Is it possible to build a faraday cage to isolate the noise to these devices? Any ideas? I was thinking about getting this:

MFJ Enterprises Inc.

Any ideas? :confused:
 
Joined
Dec 12, 2005
Messages
3,162
Location
Milwaukee, WI
#2
That noise canceler might work, but I think your noise sources are too close. If you disconnect the antenna right at the radio, can you still hear the interference? If so, then no way. Won't work.

Faraday shield may work, but you'll also have to put bypass caps on all leads entering and exiting the boxes so they don't radiate.
 
Joined
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Messages
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Location
Jacksonville, FL
#4
That noise canceler might work, but I think your noise sources are too close. If you disconnect the antenna right at the radio, can you still hear the interference? If so, then no way. Won't work.

Faraday shield may work, but you'll also have to put bypass caps on all leads entering and exiting the boxes so they don't radiate.
I have it hooked up to an MFJ Preamp tuner and when I switch it to off, I hear nothing.

Off the built in rods the noise is obviously worse.

The ground does help.

Believe it or not, the best of my radios is this new Tecsun 660, which equals or betters the 2010.
 
Joined
Dec 25, 2008
Messages
3,138
Location
New Zealand
#6
Unfortunately all your radios are in plastic boxes - the radiated interference (and re-radiated from power wiring) just goes straight in. Are you running the radios from batteries or a mains power supply? Try batteries and see if that improves things.
 
Joined
Nov 21, 2005
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266
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Home
#7
These things are mini wideband noise generators. Think of them as mini transmitting radios. Since every radio needs an antenna to effectively radiate a signal, removing any cables that run in and out of the box removes its 'antenna'. Ethernet cables - also known as UTP (Unshielded twisted pair) cables - can be the worst offenders. So my tip, if you're not already doing so, is go completely wireless.
Then you can help reduce the efficiency of any remaining 'antennas' by putting a ferrite split core, winding as many turns that'll fit through it.
If you must use Ethernet cables, hard set your speed to 10Mbit. That tends to radiate less noise than 100 or GigE.
You can also buy some nickel conductive spray paint - spray the inside of the plastic case, then earth it. Nickel spray is not easy to find, nor is it cheap - but may just be marginally cheaper than buying a large diecast aluminium case to put your noisy box inside.
One final thing to check: those nice compact & light weight switch-mode power supplies that are everywhere now are also major sources of domestic RFI. Replace them with equivalent voltage linear types and see how much improvement you get.

You can also attack the problem at the antenna side of things too, though it sounds like already done a lot in that regard. About the only other thing you could do in this area is get yourself a Wellbrook ALA1530 loop or Pixel Pro loop, and orient it away from the noise sources... assuming the noise is getting in to your system at the antenna alone. Not 100% convinced that is the case in your situation, which does complicate things. Since these antenna are expensive, try all the other suggestions first, then see if you can find someone else who can lend you a loop to try.

Last resort: big knife switch mounted on your shack wall (looks more impressive that way!) to kill all mains power to your house and run the radios on battery.
 
Joined
Jul 4, 2013
Messages
22
Location
Jacksonville, FL
#8
Unfortunately all your radios are in plastic boxes - the radiated interference (and re-radiated from power wiring) just goes straight in. Are you running the radios from batteries or a mains power supply? Try batteries and see if that improves things.
Batteries, always.
 
Joined
Jul 4, 2013
Messages
22
Location
Jacksonville, FL
#9
Last resort: big knife switch mounted on your shack wall (looks more impressive that way!) to kill all mains power to your house and run the radios on battery.
Good idea. I have the cable router and the dish amp power both connected to the same power strip (do these strips make RF noise?). If I need to dig out something buried in the hash, they get switched off and 70-80 percent of my RF noise is gone. It sounds almost like 1980 when I switch those things off.
 
Joined
Apr 1, 2008
Messages
4,472
Location
San Francisco, Ca.
#10
These things are mini wideband noise generators. Think of them as mini transmitting radios. Since every radio needs an antenna to effectively radiate a signal, removing any cables that run in and out of the box removes its 'antenna'. Ethernet cables - also known as UTP (Unshielded twisted pair) cables - can be the worst offenders. So my tip, if you're not already doing so, is go completely wireless.
Then you can help reduce the efficiency of any remaining 'antennas' by putting a ferrite split core, winding as many turns that'll fit through it.
If you must use Ethernet cables, hard set your speed to 10Mbit. That tends to radiate less noise than 100 or GigE.
You can also buy some nickel conductive spray paint - spray the inside of the plastic case, then earth it. Nickel spray is not easy to find, nor is it cheap - but may just be marginally cheaper than buying a large diecast aluminium case to put your noisy box inside.
One final thing to check: those nice compact & light weight switch-mode power supplies that are everywhere now are also major sources of domestic RFI. Replace them with equivalent voltage linear types and see how much improvement you get.

You can also attack the problem at the antenna side of things too, though it sounds like already done a lot in that regard. About the only other thing you could do in this area is get yourself a Wellbrook ALA1530 loop or Pixel Pro loop, and orient it away from the noise sources... assuming the noise is getting in to your system at the antenna alone. Not 100% convinced that is the case in your situation, which does complicate things. Since these antenna are expensive, try all the other suggestions first, then see if you can find someone else who can lend you a loop to try.

Last resort: big knife switch mounted on your shack wall (looks more impressive that way!) to kill all mains power to your house and run the radios on battery.
my modem still has cables/wires coming out of it but yet since I caged it, no more noise.
I should add that the "cage" is grounded.
 
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