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Shax



Member Since: 05 Oct 2010
Location: London
Posts: 391

England 2010 Defender 90 Puma 2.4 XS CSW Stornoway Grey
Radio interference and my quick fix..
My double USB power socket was chucking out loads of radio "hash", making reception impossible on any band..
I lashed up a simple common mode choke / filter from parts I had in my bits box.. See the pictures and schematic below. The toroid can be just about any decent type, plenty on ebay.. Capacitors are from Maplins, and are 0.1uf and .47uf 275VDC.. Wire for winding the coils is 18SWG, enamelled copper.
Fitting it inline with the USB sockets today took about 30 minutes, and the difference in reception is amazing.. I can actually hear the radio!!
It should also be useful on the cheap DRL systems that are on ebay, or any other electrically noisy upgrades!

Click image to enlarge


Click image to enlarge
 ... ,-------,
.. I [__][_]|__
.. I __ |"_|"__|
.. "(o)====(o)"
^^_-^-_^-^_^^^^^--^^^^
PAUL
G7ALW 14.200 USB
26FB458 / 27.275 SSB
Post #308730 16th Feb 2014 8:40pm
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MadTom



Member Since: 10 Sep 2013
Location: Olomouc
Posts: 618

Czech Republic 1999 Defender 130 Td5 HCPU Baltic Blue
This is the right solution. It is sad, that because of lowering prices, filters like this, are omnited from lot of new equipment. We are using this type of filter in our constructions. Thumbs Up "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo Smile
Post #308749 16th Feb 2014 9:36pm
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Egghead



Member Since: 25 Nov 2012
Location: Surrey
Posts: 255

United Kingdom 2007 Defender 110 Puma 2.4 XS CSW Java Black
Would a ferrite core clip on filter have the desired effect (for a few quid)?
Post #308785 16th Feb 2014 10:58pm
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Shax



Member Since: 05 Oct 2010
Location: London
Posts: 391

England 2010 Defender 90 Puma 2.4 XS CSW Stornoway Grey
Mine was only a few quid, and works for me.. Never tried a single clip on, but previous posts suggests that they are less than ideal.... ... ,-------,
.. I [__][_]|__
.. I __ |"_|"__|
.. "(o)====(o)"
^^_-^-_^-^_^^^^^--^^^^
PAUL
G7ALW 14.200 USB
26FB458 / 27.275 SSB
Post #308789 16th Feb 2014 11:24pm
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MadTom



Member Since: 10 Sep 2013
Location: Olomouc
Posts: 618

Czech Republic 1999 Defender 130 Td5 HCPU Baltic Blue
The clip on ferrite is very nice on frequencies around 100MHz and higher - at the input of radio. But this type of filter is better place in front of the equipment, witch produces the unwanted signals.
Clip on ferrites are nice for quick test, as you can install and remove them easily. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo Smile
Post #308843 17th Feb 2014 12:55pm
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Egghead



Member Since: 25 Nov 2012
Location: Surrey
Posts: 255

United Kingdom 2007 Defender 110 Puma 2.4 XS CSW Java Black
Ok, cheers, I'm suffering from bad radio interference and I'm not sure if the problem is caused by the additional cigarette lighter sockets wiring or HID headlamp ballast/wiring or just poor radio aerial connections. May have to try wiring up your contraption.
Post #308905 17th Feb 2014 4:33pm
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Shax



Member Since: 05 Oct 2010
Location: London
Posts: 391

England 2010 Defender 90 Puma 2.4 XS CSW Stornoway Grey
Egghead,
it's unlikely the cigarette sockets will be causing interference, maybe something that's plugged into them will..
My guess is the HID ballasts are causing the problems.. By their nature, they are very electrically noisy.

If you go down the suppression route, you'll need a dedicated suppressor for each ballast..

A quick check would be to disconnect both the HID ballasts then try the radio... If no noise, then you've found the issue! ... ,-------,
.. I [__][_]|__
.. I __ |"_|"__|
.. "(o)====(o)"
^^_-^-_^-^_^^^^^--^^^^
PAUL
G7ALW 14.200 USB
26FB458 / 27.275 SSB
Post #309001 17th Feb 2014 9:51pm
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MadTom



Member Since: 10 Sep 2013
Location: Olomouc
Posts: 618

Czech Republic 1999 Defender 130 Td5 HCPU Baltic Blue
To switch off the possible source of unwanted signal is the easiest way, how to localize the problem. It can be a part of car of a neighbours house. Problems like this are more and more common. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo Smile
Post #309063 18th Feb 2014 6:45am
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