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 Mains noise reduced 
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Post Mains noise reduced
This might help someone with their noise problems.

I didn't think my noise was too bad, but I put a mains filter in and found I could reduce my noise by a couple of S points, not an insignificant reduction.

These are the before and after videos, the first one is without the filter, the second is with the filter.






These are pictures of the filter using a FT240-43 core.

Attachment:
Mains box outside.jpg
Mains box outside.jpg [ 120.67 KiB | Viewed 171 times ]


Attachment:
Mains box inside.jpg
Mains box inside.jpg [ 172.35 KiB | Viewed 171 times ]

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Sun Jun 19, 2022 11:17 am
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 Mains noise reduced 
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Post Re: Mains noise reduced
It can make a difference.
I picked up an ex commercial one from a rally, ex GPO/BT, rated at at a full 13 amps, like yours a flying lead with a 13 amp plug on it, and a single unswitched 13 Amp socket outlet, internally it looked like yours with a ferrite ring wrapped by the conductors, plus a few capacitors dotted around various points at the input and output of the ferrite ring connections, the only major difference being it was rated at the full 13 amp plug lead rated fuse current, and the case was die cast metal, which was grounded of course.
I have used that ever since I picked it up for a couple of quid, and it does make a mains bourn noise reduction difference.

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Sun Jun 19, 2022 11:36 am
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 Mains noise reduced 
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Post Re: Mains noise reduced
G0BHD wrote:
It can make a difference.
I picked up an ex commercial one from a rally, ex GPO/BT, rated at at a full 13 amps, like yours a flying lead with a 13 amp plug on it, and a single unswitched 13 Amp socket outlet, internally it looked like yours with a ferrite ring wrapped by the conductors, plus a few capacitors dotted around various points at the input and output of the ferrite ring connections, the only major difference being it was rated at the full 13 amp plug lead rated fuse current, and the case was die cast metal, which was grounded of course.
I have used that ever since I picked it up for a couple of quid, and it does make a mains bourn noise reduction difference.


I actually made this filter for a neighbour's battery charger, but that has been replaced after I found other issues with it, like no fused plug top protecting a 3 amp rated twin lead, and the charger in an unearthed metal box, this charger is sold through Amazon and it certainly doesn't comply with the electrical regulations, let alone the EMC compliance. I've reported it to Trading Standards as dangerous electrical goods and they are investigating.

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Sun Jun 19, 2022 11:51 am
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Post Re: Mains noise reduced
G4LNA wrote:
G0BHD wrote:
It can make a difference.
I picked up an ex commercial one from a rally, ex GPO/BT, rated at at a full 13 amps, like yours a flying lead with a 13 amp plug on it, and a single unswitched 13 Amp socket outlet, internally it looked like yours with a ferrite ring wrapped by the conductors, plus a few capacitors dotted around various points at the input and output of the ferrite ring connections, the only major difference being it was rated at the full 13 amp plug lead rated fuse current, and the case was die cast metal, which was grounded of course.
I have used that ever since I picked it up for a couple of quid, and it does make a mains bourn noise reduction difference.


I actually made this filter for a neighbour's battery charger, but that has been replaced after I found other issues with it, like no fused plug top protecting a 3 amp rated twin lead, and the charger in an unearthed metal box, this charger is sold through Amazon and it certainly doesn't comply with the electrical regulations, let alone the EMC compliance. I've reported it to Trading Standards as dangerous electrical goods and they are investigating.

There is some shoddy electrical stuff about for sure, but unearthed metal cases are actually used quite often these days, but ONLY if the innards comply with the double insulated electrical standards, I have seen quite a few metal pendant lights, of the chandelier type these days that have no earth connection, just a live and neutral in a connector block, but sport the double insulated symbol on their chassis.
Does the neighbours charger carry the same square within square double insulated symbol?
The unfused supply on a 3 amp limited current supply cable is unforgivable though, it simply should have a suitable current limited protective fuse at it's connection plug end.
Internal fuses only protect the device itself, external supply plug fuses protect the connection cable.
Did it come originally with a none 13 Amp British continental type plug on it?, like a two pin round plug requiring an adaptor for use over here?, if so and that was cut off and replaced by a 13 amp plug, then its on the onus of the fitter to install a suitable fuse for the cable that feeds the device it is supplying.

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Sun Jun 19, 2022 12:02 pm
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 Mains noise reduced 
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Post Re: Mains noise reduced
:) This I like Paul.

Very simple to make with 3 core cable and an FT240-43 with 8 turns


I have a mains filter on my shack . I also lined the inside of my brick built shed with cellotex which also reduced the noise I used the plasterboard that covered it as conduit funneling the coax through ducting , most of the noise comes via common mode currents so my antennas on HF have common mode chokes at the feed point

The noise floor raises in the early evening around here,that is because I live in a town centre surrounded by hundreds of apartments sometimes it is impossible . A few years ago we had power line adapters . At Christmas the problem is usually 'lighting'

My time as a SWL taught me that having good reception and a low noise floor is everything when it comes to radio.
I used to chat to people in Banbury from S.Warwickshire on the CB as a youth and an American lady that was an employee on the USAF air base always talked about having "good ears"


Sun Jun 19, 2022 12:25 pm
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 Mains noise reduced 
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Post Re: Mains noise reduced
G0BHD wrote:
There is some shoddy electrical stuff about for sure, but unearthed metal cases are actually used quite often these days, but ONLY if the innards comply with the double insulated electrical standards, I have seen quite a few metal pendant lights, of the chandelier type these days that have no earth connection, just a live and neutral in a connector block, but sport the double insulated symbol on their chassis.
Does the neighbours charger carry the same square within square double insulated symbol?
The unfused supply on a 3 amp limited current supply cable is unforgivable though, it simply should have a suitable current limited protective fuse at it's connection plug end.
Internal fuses only protect the device itself, external supply plug fuses protect the connection cable.
Did it come originally with a none 13 Amp British continental type plug on it?, like a two pin round plug requiring an adaptor for use over here?, if so and that was cut off and replaced by a 13 amp plug, then its on the onus of the fitter to install a suitable fuse for the cable that feeds the device it is supplying.


Dunno, me Mandarin ain't so hot, how's yours?

Attachment:
back.jpg
back.jpg [ 80.4 KiB | Viewed 133 times ]


This is the plug, we replaced it with a 13 amp plug with a 3 amp fuse till I replaced the charger for him.
Attachment:
plug back.jpg
plug back.jpg [ 167.15 KiB | Viewed 133 times ]


Attachment:
plug front.jpg
plug front.jpg [ 184.41 KiB | Viewed 133 times ]


The charger is still on sale on Amazon, this is it:

https://www.amazon.co.uk/dp/B08W46GLN6/ ... eml_rv0_dp

The noise from this thing is unbelievable 20dB over S9, the neighbour lives 70m away from me, I tried the mains filter above but that only reduced it by 20dB to S9.

I've got pictures of the innards, there absolutely no provision on the PCB to even add filter components.

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Sun Jun 19, 2022 3:23 pm
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Post Re: Mains noise reduced
I've built two of these "whole shack mains filters":-

https://www.google.com/amp/s/gm3sek.com ... -2019/amp/

I'm thinking of making a few more, but they do cost about 50 quid in parts each.

Uses two ferrite cores and one clamp on ferrite and a mains filter in a can.

Rated for 13amp continuous.

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Sun Jun 19, 2022 6:35 pm
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Post Re: Mains noise reduced
What do you do with these fit them on the item that is causing noise or on the PSU for you rig??

Sorry stupid question I know but I have seen these mentioned before but not how they were implemented into the shack,

Thanks
Trevor

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Sun Jun 19, 2022 9:19 pm
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Post Re: Mains noise reduced
I use a similar one from M0NWK it's inline for the main feed to the shack, I then use a second ferrite type 31 on on the radio power supply lead as many raps as possible

https://www.m0nwk.co.uk/mains-electrici ... reduction/


Mon Jun 20, 2022 7:24 am
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I think that your supposed to fit them to everything.
Or atleast to what you believe needs it.
They stop rf from leaving your radio and going onto the mains and rf from the mains entering your rig.
I have one feeding a 8 way row of sockets for radii stuff.
And the other feeding all the other equipment equipment in the shack like test gear, soldering iron, Internet hub, computer.

According to the article, ferrite cores on all the coax coming into the shack and anything else.

I suppose it all depends how much money you have to throw at it and how much difference it actually makes to operating.

It doesn't stop the crap from a neighbours solar panel install when I point the beams that way!

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Mon Jun 20, 2022 4:31 pm
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