[time-nuts] WWVB Dephaser Question

Sat Oct 10 00:04:34 UTC 2020

Paul,

Thanks for that detailed explanation.  I've done something similar for MARS
but of course higher frequency and that was transmit also.

I've seen the site of something similar but I think that was a 3' diameter
design; and I've looked at some of the Symmetricom schematics I've
been able to find but have yet to find a schematic of one of
the Symmetricom receive antennas.  I was hoping to find the one they had
for outdoor pole mount.  It's mentioned in a lot of their documents and
even some pics but no schematic details or BOM for that I've been able to
find.

Thanks to Tim also for the response and have a good weekend!

73's,
John
AJ6BC

On Fri, Oct 9, 2020, 15:24 paul swed <paulswedb at gmail.com> wrote:

> John I don't think so as not sure how many have built a large antenna.
> Certainly any of the old wwvb receivers have details and thats pretty much
> what most people copy.
> Essentially a 3 foot copper loop with numbers of turns of wire connected
> together. Like 25 pair telco cable connected end to end. A large capacitor
> is then put across the loop to resonate it at 60 KHz. Then the preamp. Some
> use a FET transistor followed by a line driver transistor. Power is sent
> over the coax so a blocking cap and inductor.
> Really big is 10' by 10' using shielded 36 wire ribbon cable. ( did not use
> all 36 conductors it was to much L but 800 ft worth. The shield acts like
> the copper pipe and it must be broken so that it does not look like a
> shorted loop. Add the cap and preamp.
> In this case I built a 2 transistor NPN 2n3904 preamp.
> On the large antenna I use a 2 X 6 post 4ft in the ground with cement. A
> mast above that to support the antenna and to allow it to be turned a bit
> to null MSF.
> Thats it no real magic. Its been operational for 7 years with an occasional
> transistor replacement. Also coax, darn woodpeckers!
> Regards
> Paul
> WB8TSL
>
>
> On Fri, 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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