[time-nuts] Spectracom 8170 Time of Day grief...

paul swed paulswedb at gmail.com
Wed Jun 12 21:57:34 UTC 2013


Burt
One other tidbit the phase mod will exactly cause what you see.
Spectracom used phase tracking to demodulate the AM time signal. Thats why
its nuts.


On Wed, Jun 12, 2013 at 5:49 PM, paul swed <paulswedb at gmail.com> wrote:

> Burt
> There is nothing wrong with your 8170. WWVB no longer allows it to work
> correctly because of the phase modulation. They went to all psk about 1
> month ago. They had been reverting back twice a day for things like the
> 8170.
> So the ole 8170 is dead.
> You need to build something like the d-psk-r to get it going though I have
> not had time to actually add the am phase flipper precisely for the likes
> of a 8170. I have one also.
> Sorry
> Paul
> WB8TSL
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> On Wed, Jun 12, 2013 at 5:35 PM, Burt I. Weiner <biwa at att.net> wrote:
>
>> My good old Spectracom 8170 is not setting time.  I don't use it for
>> frequency, just as a clock for my Hazetorium.  I live about 20 minutes
>> north of downtown Los Angles in Glendale.  The antenna I'm using is the
>> Ferrite Rod loop in PVC that came with the 8170.  It's located on my back
>> porch just laying on the floor with its maximum pickup direction towards
>> Boulder, Colorado.  It has worked reliably for many years in that location.
>>
>> The symptoms are...  One day about a month ago I noticed that it seemed
>> to be in the start mode, that is, the far left digit was flashing between
>> 0, 1, 2, and a lot of 4's, and the left most digits were counting time
>> since an apparent restart.  Zeros and ones are the logical data states, two
>> is a place holder and four indicates data errors.  I'm not aware of it
>> having lost primary power, but it's not on a UPS.  In a week's time it did
>> not give me time sync, but shows a green locked light most of the time.
>>  This happened several years ago and a fellow at Spectracom told me to
>> change all the electrolytics on the one board that has only 4 electrolytics
>> on it.  I did and it started to work just peachy-keen.   The caps I put in
>> then were of good quality, but I decided to change them again.  This did
>> not solve the problem.
>>
>> The power supply voltages are all well within limits and they look clean.
>>  I seem to have plenty of, but not too much, signal.  By that I mean it
>> doesn't appear to be oscillating.  The antenna is about 30' away from the
>> receiver on a piece of coax that appears to look ok.  What I do notice is
>> that the signal looks like it's going through quite a bit of turbulence.  I
>> do not see anything that looks like interference.  I've looked at the
>> output of the filter amp inside the 8170 and what I see is the signal
>> dithering in amplitude quite rapidly and sometimes squaring off for a
>> moment - sort of what you would expect to see during the Diurnal Shift
>> periods of the day.  I can see the 10 dB drops, but they're not very clean
>> due to the rapid dithering.  I've checked the antenna connections and tried
>> different azimuth headings.  The location and azimuth it has been for years
>> still seems to be the best.  Looking at the output of what I'm guessing is
>> a Schmitt Trigger, I see the ST's output jumping from 0 to +5, but
>> erratically, which considering the received signal, makes sense.
>>
>> I'm wondering if I'm just in a period of time that's receiving a poor
>> quality signal?  It doesn't seem like WWVB's new phase-modulated format
>> should be causing this kind of a problem.
>>
>> All observations, opinions and suggestions are welcome.
>>
>> Thanks,
>>
>> Burt, K6OQK
>>
>>
>>
>> Burt I. Weiner Associates
>> Broadcast Technical Services
>> Glendale, California  U.S.A.
>> biwa at att.net
>> www.biwa.cc
>> K6OQK
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