[time-nuts] any HP 5370B Available or other TIC
EWKehren at aol.com
EWKehren at aol.com
Fri Aug 19 12:57:42 UTC 2011
Paul,
following all the responses to this posting I think a old fashioned D/M is
still the answer for you. For years there have been discussions on using
latest technology but limited to discussion no hardware. Maybe now is the
time it will change.
That is why two years ago I set out do develop a D/M system based on the
original NBS design but with its own counter and a cost goal of $ 200 and
readily available parts.. Thanks to Richard, Corby and Hubert there are now
eight systems out there with very good results. Cost goal was reached if 20
PC board sets are purchased. The actual D/M right from NBS, more densely
packaged for better temp. tracking and later components. Corby's tests show a
noise floor of 1 E-13. Resolution is 1 E -15. I did post in the past a
picture but it is 115K, so off list I can send more info.
What is holding up the release is software that takes the counter outputs
and does the Allan deviation calculations and plots.
What is not included in the $200 is the offset Osc,, power supply and
outside enclosure. Depending on the OCXO used it will drive the total cost to
$300 even $ 400 if 10 Hz is used. But no counter needs to be used.
If you use a 1 Hz offset many choices for OCXO are available I have used an
Austron 1150 and more recently thanks to a lead from Hubert a Morion that
is available on ebay for $40. He characterized it with the D/M system.
If you want to use 10 Hz offset the only choice I know is the HP 10811. All
the ones I have can be mechanically moved at least + - 20 Hz.
I know nothing about the Keithly 776 so I do not know if it will work. You
may want to contact me off list.
The attached drawing of the counter (thank you Brian Kirby) gives you an
idea of my counter approach. It is $ 30 of the $ 200. Tipically the phase
between channel A and B are measured, but that creates times depending of
phase when the counter can not keep up because it needs time for processing and
transfer of data. My concept does also have such a counter but it is only
used to position phase or once a run is completed to pick a section where
channel A and B are in phase to eliminate any contribution by the offset
oscillator. Two counters each per channel count the 1 or 10 Hz frequency at
100 MHz, resulting at 1 Hz with 1 E-15 and at 10 Hz 1 E-14 way better than
the D/M noise floor. The counters work in a ping pong mode so there is
continuous counting, I call it pseudo time stamping. It also allows you to "tune"
the unknown close to the reference at a 1 or 10 Hz rate. These four
counters are used for the Allan calculations.
This unit never needs a counter, once you connect Reference and PC you can
tune the offset exactly to 1 or 10 Hz, connect the unknown, "tune" it and
you are ready to go. PC interface is RS 232 or USB.
What is needed is some one tackling the PC software issue.
I will not get into the kit business. At one time I was considering to
coordinate a one time PCB run and even make some HP 10811's available since
thanks to Corby's testing, I have ten 10811 and 5071 HP OCXO's with better
than 1 E-12 over 1 to 100 sec..range, but after Jose Camara's comment that
is no longer an option for me. I will once a final board set has run with
software make all info available, and hopefully some one will pick it up.
The reason I am right now reluctant to release the PCB board code is if
changes need to be done it will be impossible to get rid of the previous code.
If any one wants go get involved software or hardware wise please contact
me off list.
Bert Kehren
In a message dated 8/17/2011 11:11:30 P.M. Eastern Daylight Time,
paulc at snet.net writes:
Hello Folks,
I am looking for an instrument that is better than Fluke 103a comparator.
The purpose of this piece of equipment is help me learn more about
oscillators and characterizing them
The HP5370B is the TIC I keep hearing about but I am not glued to that
make or model.
I wou;d like to hear suggestion from the group.
Another way to go might be to build one of those units where there is a
common oscillator is split and feeds the LO of 2 mixers.
The RF side comes from the DUT and the REF
Sorry I cannot remember the acronym... MDMM????
I do have that Keithly model 776 Counter time with GPIB I am really fuzzy
on this aspect...
Comments welcome
Thank you
PaulC
W1VLF
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