HP Laptop Brick noise

Post information or questions regarding SDRplay products here
W2DLC
Posts: 41
Joined: Tue Apr 04, 2017 1:51 pm

HP Laptop Brick noise

Postby W2DLC » Tue May 30, 2017 2:35 pm

OK, so, up until now, I've been able to solve most of the issues I originally had while learning to use the SDR for ham radio communications. The only remaining issue is that the noise level jumps from S1-2 to S-7 when I plug in my HP laptop power supply. I've tried using ferrite snap on cores, but there's no difference. I tried isolating it from ground, but that didn't help. I wrapped the brick in copper tape, and got a 1/2 S Unit reduction in noise, but that's not good enough. Does anyone have any other ideas that have worked?\
Thanks - Dan - W2DLC

Reason: No reason

DanubeBCL
Posts: 169
Joined: Sat Jul 02, 2016 12:39 pm

Re: HP Laptop Brick noise

Postby DanubeBCL » Tue May 30, 2017 3:24 pm

Laptop power supplies can be very nasty. This is not related to the brand. I owned both HP and Lenovo laptops and the PS of both were a desaster. The Lenovo PS even made reception of digital DAB+ radio impossible when it was on while the radio was in the same room.
I also tried to denoise them by enclosing them in a steel box with additional line filters at the in- and output. But they were stubborn. The noise only went down 2 or 3 S units at a general level of over S9. This was when I had a wideband loop antenna next door. Things became better when I placed the loop antenna far away from the laptop and PC outside in the garden.
Sometimes a common mode choke directly at the antenna input of the receiver helps keeping away induced noise in the coaxial cable by PS and similar. But when the noise is picked up by the antenna itself only distance between antenna and laptop helps.
The culprit with the laptops is that not only the PS makes noise, the power regulators inside the laptops make noise, too.They are difficult to denoise. On the web you can find some claims that certain brands of laptops and PS do "not interfere at all". But sorry, I think this is a fairytale. All PS from laptops I had (and other sorts of computer stuff like routers) produce high noise. And the screens (monitors) make noise, too. Just touch the screen of your laptop and watch the waterfall/spectrum.
I always wondered how these devices received the FCC and CE conformity labels ...

To sum up:
1. Distance between antenna and laptop/PS.
2. Common mode choke and/or galvanic isolator at ihe antenna input.
3. Replacing the switched PS by a (homemade) linear PS for the laptop. But this is easier said than done.

73, Heinrich

Reason: No reason

W2DLC
Posts: 41
Joined: Tue Apr 04, 2017 1:51 pm

Re: HP Laptop Brick noise

Postby W2DLC » Tue May 30, 2017 6:26 pm

Yes, I've been seriously considering building a filtered and regulated power supply.

Reason: No reason

DanubeBCL
Posts: 169
Joined: Sat Jul 02, 2016 12:39 pm

Re: HP Laptop Brick noise

Postby DanubeBCL » Wed May 31, 2017 6:05 am

W2DLC wrote:Yes, I've been seriously considering building a filtered and regulated power supply.
Yes, good idea. But you have to consider the high amperage the laptops often need. E. g. my 8 year old Lenovo (non-gamer, standard office laptop!) consumes up to 15 A at 23 Volts. I also seriously thought about building a PS myself by I could not get a suitable old style mains transformer for this.
In the meantime I no longer use laptops for radio reception. I prefer that good old desktop style PCs with a decent metal cabinet. I found that their PS are much more quiet than the external plastic enclosed PS which come with the laptops, and additional line filters plus grounding of the case easily iron away the minimal rest noise which they have.

73, Heinrich

Reason: No reason


Return to “SDRplay related”

Who is online

Users browsing this forum: No registered users and 1 guest