For my little WWVB project I used the table saw to cut off the
upper 3 inches of a 5 gal bucket from Lowes (having removed the handle
first).
Then I wrapped that with about 30 turns of enameled wire from
an old TV flyback transformer. I then measured the inductance
and added the required capacitance to tune it to 60 kHz.
I am doing direct sampling with a teensyduino and sound card.
I have not tackled the phase decoding, which would be superior.
https://github.com/chris-elfpen/Teensy4WWVBsdr
On 10/9/20 7:04 PM, John C. Westmoreland, P.E. wrote:
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 <paulsw...@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. <
j...@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 <kb...@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. <
j...@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 <paulsw...@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 <rcb...@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 <kb...@n1k.org>
Date: Thu, October 08, 2020 12:40 pm
To: Discussion of precise time and frequency measurement
<time-nuts@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, <rcb...@atcelectronics.com> <
rcb...@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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