[time-nuts] WWVB clocks no longer lock (Was: Used Spectracom)

paul swed paulswedb at gmail.com
Fri Jan 18 00:42:08 UTC 2013


Issue is any system that phase locked will not and then not decode
Mobile so can't go into detail
Paul
Wb8tsl

On Thursday, January 17, 2013, Clint Turner wrote:

> At about the time WWVB announced switching the format, two of my clocks -
> identical "SkyScan" units bought at about the same time 10 or so years ago
> suddenly stopped synchronizing, too.  If just one of these clocks had a
> problem, I would chalk it up to a random failure - but two of them?
>
> One of these clocks is in my ham shack, next to a different model clock
> (one displays UTC, the other local) and this other clock hasn't missed a
> beat while the other is on the wall, well away from any noisemaker like a
> switcher or a CFL.  I've actually swapped these clocks and neither one is
> happy.  I've also put a different brand clock in its place and it maintains
> synchronization just fine.
>
> I've checked for noisemakers (switching supplies) and found a noisy one -
> and then quieted it down with added filtering, but even before I did this
> it hadn't affected a clock only a few feet away from it!
>
> The *only* time that these clocks lock up is when I first install the
> battery, but from then on they claim to be locked, but are drifting away
> from proper time.
>
> For one of these, I popped the cover and found the trace with the WWVB
> time code from the die-mounted receiver chip and it looks pretty clean:  No
> "stuttering" is apparent, but I didn't make any attempt to time every type
> of mark or space to verify its timing.
>
> The fact that it synchronizes just once is puzzling - as is the fact that
> just this particular model is now unhappy:  Was even a minor change made to
> the AM portion of the code?  I could imagine that a too-narrow bandpass
> filter could slightly affect the timing of the pulses as the phase flipped,
> but even if this were the case, why does it always synchronize just the one
> time and then never again?
>
> 'Tis a puzzlement...
>
> 73,
>
> Clint
> KA7OEI
>
>
>
> J.L. Trantham wrote:
>
>> I have two 'cheap' WWVB 'Atomic Clocks', both of which say they are
>> 'locked'
>> and are about 2 minutes apart.
>>
>> Joe
>>
>
>
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