Sometime in the late 1990s, a friend of mine who works for a local city
government asked me if there was something that I could do about some
WWVB clocks located in a conference room, downtown, on a middle floor of
an office building amongst computers and fluorescent lights that never
managed to get the correct time.
Together, we built this:
http://ka7oei.blogspot.com/2013/03/getting-atomic-wwvb-clocks-to-work.html
It's been in operation since it was installed, except for two occasions:
- After a few weeks it quit working so my friend opened the cover of the
outdoor unit to take a look. Once the water drained out, it started
operating again. (He then drilled a drain hole and sealed everything
else a bit better.)
- Last year - after somewhat more than a decade of operation - it quit
working when the electrolytics in the transformer-type "wall wart" that
powered it dried out and there was several volts of AC riding atop the
DC output. A new wall wart was procured and I added a large capacitor
in the indoor amplifier's box as well.
The original plan was to drop the receiver coupling loop down, through
the stud space in the wall behind the clocks, but it turned out that
just laying them atop the drop ceiling provided more than enough signal
and that's where things have been.
When getting it back in service after the more recent work I did some
testing and found that I had to get the outdoor antenna and the indoor
coupling loops within 15-20 feet of each other (and oriented properly)
in order for the system to oscillate, but this close distance - and
optimal loop orientation for mutual coupling - should be easy to avoid.
I would thing that the outdoor amplifier/loop coupling could be
optimized somewhat, but it provided many 10's of dB of margin when
checked on a receiver. (The several millivolts/meter field strength
around here doesn't hurt, either!)
73,
Clint
KA7OEI
Chuck Forsberg WA7KGX wrote:
I'd like to see a WWVB generator that could output the 60 KHz WWVB signal
through a sound card for the benefit of hard of hearing "atomic" clocks
by Oregon Scientific and others.
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