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

[Burt I. Weiner]

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