Wide band interference

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Patrick73
Posts: 223
Joined: 22 Mar 2015 12:36
Location: french Alps, JN35am

Wide band interference

Post by Patrick73 » 14 Apr 2018 09:23

Hi there !

Does anyone know what can generate this kind on interference ?
Those verticale lines are visible, at least, from 70 to 160 MHz ... (maybe below / above, my antennas are pretty deaf out of this range).

I can make them slightly less visible by rotating the dipole / Yagi but as I live in an appartement (antennas are mounted on the balcony, about 3m from the building's facade) I can't keep them far from my radio corner. The band was pretty "clean" last year, using the same antennas.

Do you think some ferrite toroids (FT240-31) could help a bit ?

:(
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Patrick
Main interests : NDB, MW & FM DX'ing
REU Editor http://www.classaxe.com/dx/ndb/reu

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zach_m
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Location: Hatfield, Herts
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Re: Wide band interference

Post by zach_m » 14 Apr 2018 23:08

I also have a problem with spikes all over the band. What I did first, is clipped all my USB cables with ferrite cores. I also put a few ferrite clips on psu cable. There is a massive difference now, but there are still spikes that I cannot eliminate. I presume these came from the environment around (neighbours) and (possibly) solar panels that are installed not far from our flat.

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zach_m
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Re: Wide band interference

Post by zach_m » 14 Apr 2018 23:12

And here is the worst part of the band!
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Patrick73
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Location: french Alps, JN35am

Re: Wide band interference

Post by Patrick73 » 15 Apr 2018 08:02

Your "worst part of the band" is much cleaner than mine !!!

I actually have a single USB cable, the one from the desktop to the SDR and it's a double-shielded one. I tried another one with 2 'built-in' ferrites : no improvement.
I also put a ferrite clip on the PSU and the monitor cable, no effect. I added a couple of ferrites on the coax cable (from the SDR to the antenna) : this makes noise level clearly drop on shortwaves ; no improvement on VHF. The number of spikes is the same when using a quality satellite cable instead of rather poor 50 ohms coax (less than 10 meters long).

I have 2 types of ferrite clips, black and grey ones (no idea on their material). I just noticed the black ones are pretty effective (especially on HF), but the grey ones have no effect at all, whatever the frequency is.
Patrick
Main interests : NDB, MW & FM DX'ing
REU Editor http://www.classaxe.com/dx/ndb/reu

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