It turns out Bobs dumpster was my dumpster by a long path. I still have the sampling HP54100 1 Ghz scope and it works. Many other lucky bits to get. Best regards Paul WB8TSL
On Mon, Feb 24, 2020 at 1:43 PM Bob kb8tq via time-nuts < [email protected]> wrote: > Hi > > Yup, welcome to the online auction lottery ….. As you may have noted, I’m > struggling a bit with the Phase Station and random (likely my fault) > issues. > > At the same time, I’m going around in circles about the R&S FPC-COM2. It’s > a pile of money, but it would replace a lot of questionable gear I have > sitting > here. Most of what I have was quite literally pulled from / saved from the > dumpster at various points over the last few decades ….. > > Bob > > > On Feb 24, 2020, at 12:33 PM, Taka Kamiya via time-nuts < > [email protected]> wrote: > > > > I woke up this morning, check my HP105B, it's absolutely going nuts. > Heater temp down, frequency ALL OVER the place. No output in any of the > ports. Sigh..... eBay strikes again! > > > > --------------------------------------- > > (Mr.) Taka Kamiya > > KB4EMF / ex JF2DKG > > > > > > On Sunday, February 23, 2020, 7:52:02 PM EST, Bob kb8tq via time-nuts > <[email protected]> wrote: > > > > Hi > > > > Ok, but thats “high pass in the RF section”. You really do not have an > audio high pass > > filter the way you would in a more typical DMTD. > > > > If it’s any comfort, I’m sitting here looking at a very different box. > It also has “wobbles” > > as you get into parts in 10^-16. That might change a bit if the draft > coming through the > > window was a bit less. > > > > Bob > > > >> On Feb 23, 2020, at 6:12 PM, Jan-Derk Bakker <[email protected]> > wrote: > >> > >> Dear Bob, > >> > >> The capacitors are 47n NP0/C0G types (Kemet C0805C473K3GAC7800), picked > for low tempco (and low DF and other non-ideal behavior). I've not spotted > any hysteresis artefacts in these in previous designs, but I haven't > measured their performance in this circuit. > >> > >> Forgot to mention in the previous message: the baluns are transformers > (M/A-COM MABAES0060), so the only DC the ADC should see is its own input > offset (plus offset current across the 25R input filter resistors). Full > schematic is here ( http://www.lartmaker.nl/time-nuts/DMTD_rev0.99.pdf < > http://www.lartmaker.nl/time-nuts/DMTD_rev0.99.pdf> ; needs cleanup, but > all connections are there). > >> > >> JDB. > >> > >> On Sun, Feb 23, 2020 at 10:13 PM Bob kb8tq <[email protected] <mailto: > [email protected]>> wrote: > >> Hi > >> > >> What does the temperature coefficient of your “hardware HPF” filter > caps look like? > >> Are they a type that has significant hysteresis? > >> > >> Bob > >> > >>> On Feb 23, 2020, at 3:05 PM, Jan-Derk Bakker via time-nuts < > [email protected] <mailto:[email protected]>> wrote: > >>> > >>> Dear Attila, > >>> > >>> Thanks for the heads up. > >>> > >>> I am currently using a HPF both in hardware (capacitive coupling into > the > >>> balun driving the ADC inputs) and in software before the ZCD. This > should > >>> counteract the first-order effects of this offset, although > second-order > >>> effects (converter nonlinearity et al) will of course still be an > issue. > >>> The plots you've quoted include (different kinds of) DC offset > correction > >>> for all but the "unfiltered" data; getting an efficient DC offset > >>> correction working in real time on this 8-bit platform was indeed one > of > >>> the main challenges of the software-only approach. > >>> > >>> The FPGA daughterboard is currently in production at Eurocircuits; I > hope > >>> to have time to work on those the coming month. I'll also try to book > some > >>> time in our climate chamber. (I've had one of our GPSDO-designs > running in > >>> our general labs since before Christmas; surrounding it with bottles of > >>> water works well enough to low pass filter temperature swings, but I > still > >>> see 6 degrees C swings overnight as out HVAC only runs during business > >>> hours.) > >>> > >>> To be continued, > >>> > >>> JDB. > >>> > >>> On Sun, Feb 23, 2020 at 8:11 PM Attila Kinali via time-nuts < > >>> [email protected] <mailto:[email protected]>> wrote: > >>> > >>>> Good evening! > >>>> > >>>> I'm going through some old stuff... > >>>> > >>>> > >>>> On Wed, 27 Nov 2019 00:29:19 +0100 > >>>> Jan-Derk Bakker <[email protected] <mailto:[email protected]>> > wrote: > >>>> > >>>>> This has yielded a combined "simple" signal > >>>>> processing path of a differentiator, a double comb filter and the > offset > >>>>> estimator, which is getting very close in performance to the "ideal" > band > >>>>> pass filter (OADEV of 3.77e-13@tau=1s versus 3.25e-13@tau=1s for the > >>>> BPF; > >>>>> full plot: > >>>>> > >>>> > http://www.lartmaker.nl/time-nuts/DMTD%20self-noise%20OADEV%20with%20PLL%20and%20various%20filters.pdf > < > http://www.lartmaker.nl/time-nuts/DMTD%20self-noise%20OADEV%20with%20PLL%20and%20various%20filters.pdf > > > >>>>> for this 600000-second recording: > >>>>> > >>>> > http://www.lartmaker.nl/time-nuts/600ksec%20run%20with%20PLL,%2010811%20through%20splitter.png > < > http://www.lartmaker.nl/time-nuts/600ksec%20run%20with%20PLL,%2010811%20through%20splitter.png > > > >>>>> . OADEV past ~1000sec is severely compromised by the fact that the > >>>>> measurement setup is in my home lab which sees temperature swings of > up > >>>> to > >>>>> 20 degrees C and which does get bumped from time to time. Longer > runs in > >>>> a > >>>>> more controlled setting forthcoming). > >>>> > >>>> > >>>> I can offer an explanation for the large effect of the zero > correction seen > >>>> here. The LTC2140 is specified to have a +/-10µV/°C drift (at 1Vpp > >>>> setting). > >>>> Converted into phase error due to zero crossing shift, this turns into > >>>> a phase shift of +/-1ps/°C @ 10MHz. Note, the shift is given as +/- > and > >>>> per channel, which means, it could very well be that the channels are > >>>> not matched in their temperature characteristics and thus the total > phase > >>>> shift could be +/-2ps/°C ... though total shift being closer to > 0.5ps/°C is > >>>> more likely. > >>>> > >>>> Summa sumarum: DC offset correction is important if a zero crossing > >>>> detector is used. > >>>> > >>>> Attila Kinali > >>>> > >>>> -- > >>>> <JaberWorky> The bad part of Zurich is where the degenerates > >>>> throw DARK chocolate at you. > >>>> > >>>> _______________________________________________ > >>>> time-nuts mailing list -- [email protected] <mailto: > [email protected]> > >>>> To unsubscribe, go to > >>>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com < > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > >>>> and follow the instructions there. > >>>> > >>> _______________________________________________ > >>> time-nuts mailing list -- [email protected] <mailto: > [email protected]> > >>> To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com < > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > >>> and follow the instructions there. > >> > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
