Re: [IRCA] Modem Noise

[Patrick Martin <mwdxer@xxxxxxxxx>]

Walt,

I am an old hand with electronics. First of all, the modem is grounded through the coax. A Faraday type box is what is needed, since the shielding already has killed 95% of the noise. Happy New Year.

Patrick

Patrick Martin
Seaside OR
KGED QSL Manager

> From: canswl@xxxxxxxxx
> Date: Fri, 2 Jan 2015 02:43:42 +0000
> To: irca@xxxxxxxxxxxxxxxx
> Subject: Re: [IRCA] Modem Noise
> 
> Careful, Patrick that you don't electrocute yourself, or cause a fire!
> Patrick, I think that a SDR would be very beneficial to you in seeing the
> noise.  I find my Perseus invaluable in assessing noise issues, light-years
> ahead of simply listening to a single frequency like in the old days!
> 73,...Walt
> 
> On Fri, Jan 2, 2015 at 2:23 AM, Patrick Martin <mwdxer@xxxxxxxxx> wrote:
> 
> > Happy New Year everyone,
> >
> > You may remember me posting about the cable modem noise I was getting
> > after I got the high speed internet in late 2013. I fought with that for a
> > long time. I got a little bit of it reduced, but it was still an issue. So
> > when I would DX, I often would turn the phone/internet modem off, leaving
> > the calls transferred to my cel phone. The other day, we had an outage. We
> > lost the phone as well as the internet off and on. When it came back up,
> > the phone still did not work right. I called Charter and a CSR sent a
> > "ping" down the line and the ping did not come back correctly. They sent a
> > tech out and in the process I mentioned the horrible harmonics coming from
> > the modem. I showed him what I meant. In conversation, he mentioned that
> > the old modems did have a noise issue as they were interfering with rotors,
> > so he replaced the old phone/internet modem with a new one. When the phone
> > and internet came back up, 50% of the noise (at least) was gone. Apparently
> > the new one has a better pow
> >  er supply, less noisy. After he left I decided to try and get rid of the
> > rest of the noise. So as an experiment, I wrapped the box in tin foil and
> > grounded it to the coax connection. The noise was gone. Of course I could
> > not leave it wrapped like that, as the modem has air holes in the plastic
> > box. I had an old analog converter box, so I took the top off and places it
> > over the modem, like a little garage as there are sides on it, leaving it
> > open on the front and back. No difference, not until I grounded the box to
> > the coax ground and the noise dropped down about 95%. There is still a bit
> > on one frequency on the R8, but weak, plus I plan to get some screening and
> > cover it with that. I think that should rid myself with the rest of the
> > noise.
> >
> > Patrick Martin
> > Seaside OR
> > KGED QSL Manager
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