[time-nuts] WWVB Dephaser Question

paul swed paulswedb at gmail.com
Fri Oct 9 22:00:39 UTC 2020 

Have built whips and small loops and ferrite cores of various sizes. For me
the best is the 10' by 10'. As mentioned earlier in the thread as measured
on a dymec receiver. Other solutions during the day 10-30uv. Large loop
60-200. Night is just crazy up in the millivolt range. But not all of the
time. It just depends on propagation.
In New England the antenna does need the ability to null MSF out of
England. A bit of a trade off.
Last comment. Listening today and really seeing the noise floor upto 70-80
KHz climbing. Still tracking wwvb just fine but I fear far sooner then
later that may not be the case.
Regards
Paul

On Fri, Oct 9, 2020 at 5:42 PM Tim Shoppa <tshoppa at gmail.com> wrote:

> The NIST WWVB transmitter antenna is very massive and very well
> documented: https://apps.dtic.mil/sti/pdfs/ADA299080.pdf
>
> For receive on VLF there is no reason to go so big. A short whip produces
> plenty of atmospheric noise so there’s no purpose at going bigger. A loop
> (including ferrite core loop) has a useful null to remove local noise
> sources. A tuned loop with reasonable Q helps reject a lot of noise before
> it reaches the first active stage.
>
> Tim N3QE
>
> > On Oct 9, 2020, at 5:14 PM, John C. Westmoreland, P.E. <
> john at westmorelandengineering.com> wrote:
> >
> > Bob,
> >
> > Thanks for the answer; but does anyone actually have a documented
> > specification posted for one of these 'massive' WWVB 60kHz antennas
> > someplace?
> >
> > Thanks.
> >
> > 73's,
> > John
> > AJ6BC
> >
> >
> >> On Fri, Oct 9, 2020, 08:35 Bob kb8tq <kb8tq at n1k.org> wrote:
> >>
> >> Hi
> >>
> >> At least to me, anything dimensioned in the 100’s of feet is “massive”
> >> compared to
> >> the rod antennas normally seen in WWVB use ….
> >>
> >> The other point being that if the antenna is some sort of large loop,
> it’s
> >> going to be
> >> a good long ways away from the receiver. You get both a larger signal
> >> voltage and better
> >> isolation …..
> >>
> >> Bob
> >>
> >>> On Oct 8, 2020, at 11:30 PM, John C. Westmoreland, P.E. <
> >> john at westmorelandengineering.com> wrote:
> >>>
> >>> Hello All,
> >>>
> >>> Are there any design details someplace regarding these massive
> antennas?
> >>>
> >>> Thanks,
> >>> John
> >>> AJ6BC
> >>>
> >>>
> >>>> On Thu, Oct 8, 2020, 19:27 paul swed <paulswedb at gmail.com> wrote:
> >>>
> >>>> Hello to the group.
> >>>> Ray as Bob mentions you are taking a 10s of uv signal to a logic level
> >> of
> >>>> maybe 4V.
> >>>> If the loop is any place close to the divided down signal, it will
> >>>> oscillate. It would take incredible shielding to protect the receiver.
> >>>> Thats why you often see a solution that doubles to 120 KHz and
> modifies
> >> the
> >>>> detectors to work at that frequency. That means hacking the radio
> >>>> internally. Not fun. The other really annoy effect is that the
> doubling
> >>>> slips phace due to noise and propagation. So if charting suddenly you
> >> get a
> >>>> 180 degree flip. Thats messy.
> >>>> The doubling solution can work. Search for carter and there are
> several
> >>>> others.
> >>>> But having tested and used all of the alternates and lots more on the
> >> east
> >>>> coast decided they were too much trouble. You should see the box of
> >> boards
> >>>> I have chuckle.
> >>>> For me I am very happy with the d-psk-r. Though in being above board I
> >>>> designed version 1 and Rodger and I did version 2. Its solid and no
> >> mods to
> >>>> any receiver. Everything has always been released to the time-nuts
> >> group.
> >>>> As they say have fun.
> >>>> Regards
> >>>> Paul.
> >>>> WB8TSL
> >>>>
> >>>> On Thu, Oct 8, 2020 at 5:39 PM <rcbuck at atcelectronics.com> wrote:
> >>>>
> >>>>> Bob,
> >>>>>
> >>>>> I am using a ferrite rod antenna for the receiver. No outside
> antenna.
> >>>>>
> >>>>> Ray
> >>>>>
> >>>>> -------- Original Message --------
> >>>>> Subject: Re: [time-nuts] WWVB Dephaser Question
> >>>>> From: Bob kb8tq <kb8tq at n1k.org>
> >>>>> Date: Thu, October 08, 2020 12:40 pm
> >>>>> To: Discussion of precise time and frequency measurement
> >>>>> <time-nuts at lists.febo.com>
> >>>>>
> >>>>> Hi
> >>>>>
> >>>>> A lot depends on your antenna setup. You can also swamp out the
> >> incoming
> >>>>> WWVB signal…….
> >>>>>
> >>>>> Bob
> >>>>>
> >>>>>> On Oct 8, 2020, at 2:07 PM, <rcbuck at atcelectronics.com> <
> >>>>> rcbuck at atcelectronics.com> wrote:
> >>>>>>
> >>>>>> I have read several different articles where the WWVB phase shift is
> >>>>>> eliminated by doubling the signal to 120 kHz. Several members of the
> >>>>>> list have built these units.
> >>>>>>
> >>>>>> Assume I build a circuit to double the incoming signal and use a
> >>>> schmitt
> >>>>>> trigger to get a 120 kHz square wave. If I then divide that signal
> >> back
> >>>>>> down to 60 kHz will that signal be strong enough to swamp out the
> WWVB
> >>>>>> signal? I'm guessing it will be since it is at the 5 volt level and
> >>>>>> somewhere in the +25 dBm or greater range.
> >>>>>>
> >>>>>> Ray,
> >>>>>> AB7HE
> >>>>>>
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