[time-nuts] WWVB remodulator for the Spectracom 8170...

[Burt I. Weiner]

Chris,

The 8170 was originally intended to be a frequency reference source 
tied to the USFS (United Stated Frequency Standard).  It also gave 
the time of day, but I believe that wasn't it's primary purpose.  As 
I recall, there were some versions that did not have the clock 
readout and some that had a chart recorder.  Back in the 80's I used 
to drool (it was a disgusting sight!) over the Spectracom receivers 
with the chart recorders.  At that time I was usuing a Gertsch RLF-1 
with an external Moseley 680 chart recorder.  The remodulator 
precludes it from being used as a frequency standard, but in my 
opinion, so does the fact that WWVB is now phase shifted a bunch.

The 8170 uses a coherent detector and that's where the problem 
lies.  While the 8170 still locks to the WWVB carrier, the new BPSK 
scheme causes the detector to output bad data in spite of the 
original dips in the carrier still being present.  I had always 
wondered how it was able to pull the data out the noise, but never 
had a manual until just recently.  I had naively assumed that the 
WWVB new BPSK scheme would not affect the time of day aspect of the 
8170.  Like I said, I only use it as a clock in my shoppe, and being 
an old dog I don't easily learn new tricks such as looking in a 
different direction for one of the other clocks.

Burt, K6OQK

From: Chris Albertson <albertson.chris at gmail.com>
At 02:08 PM 6/17/2013, time-nuts-request at febo.com wrote
>Yes, I see what it does.   It is a simple circuit.  But I just thought
>(wrongly, now I see)  that the 8170 somehow used the 60KHz signal for some
>purpose.  I gues not,  It is just a carrier that is discarded.
>
>Some receivers used the 60HKz signal as a 60KHz frequency reference and
>phase locked their internal clock to the 60KHz signal.  I gues the 8170
>does not do that.

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
biwa at att.net
www.biwa.cc
K6OQK