Yes, I'm sure. I did check the cabling. :) If I was somehow measuring
the Tbolt or 4065A against itself, there wouldn't be any frequency offset.
The Oscilloquartz 3210 (which appears to be an OEM'd 4065A) is spec'ed
at 3E-13 @ 100K seconds. The 4065C is even better at 8.5E-14 with a
noise floor of 5E-14.
My data run is continuing. The end of the graph is flopping around as
usual, but it's now showing Total Deviation of about 1.4E-13 @ 100K
seconds with a total of 226 800 readings at 1 second intervals.
Frequency offset error is still 6E-13. Autocorrelation of the results
shows diurnal spikes at approximately 86 160 and 172 310 seconds (i.e.
one and two sidereal days).
Ed
On 11/14/2014 11:00 AM, Azelio Boriani <[email protected]> wrote:
Are you sure you are measuring the 4065A against the Tbolt? TBolt
feeding the start and 4065A feeding the stop and a counter in time
interval mode?
On Fri, Nov 14, 2014 at 3:26 PM, Ed Palmer <[email protected]> wrote:
FYI, I found a source for the PLCC44 version of the STEL-1173 that's used in
some Datum FTS Cesium standards. I got mine from here:
http://www.aliexpress.com/item/Free-shipping-10PCS-STEL-1173-CM-PLCC/2023682701.html
I left positive feedback, not sure why it doesn't show.
Shipping was very slow, but the chips appear to be NOS. There are no
scratches on the leads which suggests that they were never installed in a
socket. I was having trouble with one so I decided to sacrifice it to see
what was inside it. The die is labelled 'ORBIT B-100'. When I chopped out
the dead chip from my FTS-4065A, the bottom was stamped with the word ORBIT.
ORBIT Semiconductor works on FPGA to ASIC conversions. It looks like
Stanford used Orbit as a fab house.
I'm currently measuring my 4065A against my Tbolt. After about 37 hours,
I'm still not seeing anything that I can attribute to the 4065A. All I'm
seeing is the Tbolt and the typical response that every GPSDO gives. I'm
looking at Total Deviation values of around 1E-13 at 100Kseconds. Frequency
offset error appears to be about 6E-13.
All diagnostic status values are within spec. I had to adjust the signal
level from the tube - it was too HIGH!
I decided to solder in a socket so that I won't have to go through any pain
if this chip dies in the future - and I now have spares!
Ed
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