Interested to know how much noise would be from USB signalling and how much is " machine noise" from the PC as my understanding of USB signalling is that it's differential so such should be low noise?
I'm also not sure I've ever seen a non screened usb cable? On Fri, 18 May 2018 1:17 pm Dana Whitlow, <k8yumdoo...@gmail.com> wrote: > Caution, folks, about USB cable radiation. While the intended signals > flowing through the > cable presumably contribute a bit to the overall picture, common-mode > currents on the cable > are the most likely cause of severe radiation problems. These currents > arise not merely from > intended USB signals, but from *all* the digital activity within the > device, and will be present > whether or not USB communications are going on. > > The keys to controlling this problem are: > > 1) Shielding on the USB cable. > 2) Proper design inside the USB device, rarely done beyond the point of > (barely) meeting > government regulations, which are far too forgiving IMHO. > 3) Use of a ferrite choke on the cable to reduce those residual currents > that get by anyway. > > Note that only item 3 might be under the control of the user to any useful > extent. > > So please don't just assume that using a USB cable for charging only solves > anything. > > Note that the above comments are also generally applicable to *all *cables, > including power > cables, that are plugged into *any* digital device. > > Dana K8YUM > > > > On Fri, May 18, 2018 at 5:15 AM, David J Taylor via time-nuts < > time-nuts@febo.com> wrote: > > > Anyone who is using one (or both) of these, and/or folks who have a > > logical opinion: > > [] > > There's more... but this is a good start. Just want to try and get > > parts on the way. Have to build a separate outboard regulator for the > > timing GPS antenna, too. > > > > Thanks! > > > > Clay Autery > > ============================= > > > > Clay, > > > > I have all three of these units, all powered off USB. I don't see any > > reason why you shouldn't use a USB cable with just the DC part connected, > > so that there's no issue about radiation. A standard USB port would only > > supply 0.5A so that's an upper limit on the power consumption. If it's a > > very long USB cable (you mention mast-head) check the resistance. > > > > As a crude guide... > > > > - The (larger box) NTP server feels cold to the touch. > > > > - The smaller, single output frequency source feels very slightly warm to > > the touch (feeding an Icom IC-R8600) > > > > - The larger, dual-output frequency source feels slightly warm to the > > touch. > > > > There's an e-mail address where you could ask: supp...@leobodnar.com > > > > Cheers, > > David > > -- > > SatSignal Software - Quality software written to your requirements > > Web: http://www.satsignal.eu > > Email: david-tay...@blueyonder.co.uk > > Twitter: @gm8arv > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/m > > ailman/listinfo/time-nuts > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
