[time-nuts] WWVB Chronverter update progress

paul swed paulswedb at gmail.com
Wed Aug 29 11:36:20 EDT 2018


Its a LPF and its not effecting anything. Square waves worked fine
actually. But do want to be able to feed an antenna so a bit of filtering
plus the loops stick should do the job.

On Wed, Aug 29, 2018 at 9:16 AM, Bob kb8tq <kb8tq at n1k.org> wrote:

> HI
>
> If you are feeding “Time Nuts” gear, a fancy filter on the output of the
> WWVB gizmo may be an issue. Temperature impacts the value of the
> components and that value change impacts the phase of the signal….
>
> Bob
>
> > On Aug 28, 2018, at 9:33 PM, paul swed <paulswedb at gmail.com> wrote:
> >
> > LPF filter added 2.2mH choke to a .0022uf cap 1K R pretty simple and
> > anttenuators and isolation to drive up to 4 receivers.
> > Have not looked at the power amp and loops stick antenna yet. But it
> really
> > is time for GPS a neo.
> > Looking very good.
> >
> > On Tue, Aug 28, 2018 at 7:29 PM, paul swed <paulswedb at gmail.com> wrote:
> >
> >> Ed appreciate the details but no intent to generally run a GPSDO in fact
> >> the 5 V @ 50 ma is a serious power pig. The chronverter draws 5 ma.
> Clearly
> >> the TTL is a heater. Chuckle. I do want to drive the chronverter with
> GPS
> >> as its designed for.
> >> Whats pretty interesting is you can adjust its offset. I just jammed
> time
> >> into it several days and its been fairly good with power ups and down.
> Its
> >> impressive. Though not in an ultimate time-nuts way.
> >> GPS just assures it is accurate. But there is a lot of flexibility.
> >> Main goal of this whole project is to replace wwvb if it goes away. If
> it
> >> does the project doesn't even have to run 24/7. Fire up at 10 pm to 3 am
> >> and power down. Thats enough to set my wall clocks for a day. Its just
> nice
> >> to know it can also set the spectracoms and Truetimes. Icing on the
> cake.
> >> I am impressed with what Dave did with the 8 pin pic. He has all of the
> LF
> >> time signals in there. (No wwvb BPSK though) DSTs settings, zone
> offsets,
> >> half zones, etc.
> >> Just looking at low pass filters for the 60 KHz ttl out right now.
> Simple
> >> LR or RC. Since this particular output feeds coax to the quality
> receivers
> >> I don't need to be that careful. Its working great without any
> filtering.
> >> Reality if it draws little power I will let it run 24/7 but then you
> just
> >> have to stick a display on at that point.
> >> Regards
> >> Paul
> >>
> >> On Tue, Aug 28, 2018 at 7:11 PM, ed breya <eb at telight.com> wrote:
> >>
> >>> Paul,
> >>> If you're going to reference it from a GPSDO anyway, why worry about a
> >>> TCXO reference (and power too, for that matter). You can easily make
> the 60
> >>> kHz from the 10 MHz.
> >>>
> >>> For example, with two 74HC390s and a 74HC86 you can make 50 kHz and 10
> >>> kHz and mix them with one EXOR section of the '86 to have 60 kHz
> available.
> >>> Some fairly simple bandpass filtering should select and clean it up
> >>> sufficiently. Two other sections of the '86 can be set up as inverters
> and
> >>> self-biased as amplifiers - one to convert the 10 MHz sine reference to
> >>> logic, and the other from the filter output to logic, if needed. And,
> you'd
> >>> still have a divide by 5 and an EXOR left over to fool around with.
> >>>
> >>> The same parts and process can be done at a higher frequency and then
> >>> divided down afterward. (5+1) MHz/100, and (500+100) kHz/10 would work
> too.
> >>> It depends on what frequency you prefer for the BPF. If you go high at
> 6
> >>> MHz, you then have the option to make a crystal filter from readily
> >>> available parts.
> >>>
> >>> Going the high way also provides for higher logic frequencies that are
> >>> more or less in sync, in case you want to do any I-Q modulation type
> stuff
> >>> - you can even use synchronous counters instead, to really make sure.
> >>>
> >>> Overall, I think I'd recommend going at 5+1= 6 MHz, filtering with 6
> MHz
> >>> crystals, then dividing down to 60 kHz, with 2f and 4f clocks
> available for
> >>> I-Q use. I sketched out a quickie circuit that's quite simple and I
> think
> >>> would do. It would take two HC390s for the dividing, as before. Each
> HC390
> >>> is two divide by 10 counters, including a 1/2 and 1/5 in each, usable
> >>> separately. So, with two parts, there are four 1/5s and four 1/2s
> available.
> >>>
> >>> Here's a verbal process description: 10 MHz sine convert to logic with
> >>> HC86, 10 MHz/2=5, 10 MHz/10=1 with first HC390, add 5+1=6 with EXOR,
> BPF 6
> >>> MHz, convert to logic with HC86, 6 Mhz/25=240 kHz=4f, 240/2=120 kHz=2f,
> >>> 120/2=60 kHz=f, with second HC390.
> >>>
> >>> Ed
> >>>
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> >>>
> >>
> >>
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