[time-nuts] Dual Mixer
EWKehren at aol.com
EWKehren at aol.com
Tue May 11 14:02:32 UTC 2010
The Dual Mixer project is nearing completion.
Let me refresh every ones memory as to my goals.
a) Total cost less than $ 200
b) 1 E-13 with a one second offset
c) use parts attainable by every one
d) easy to assemble only a few surface mount parts
e) a five channel counter that yields 1 E 15 resolution and interfaces
directly to a PC via RS232 or USB
f) A counter that also gives you instant frequency difference at the
sample rate, not only Allan Variance
g) Modular so one can use only the Dual Mixer
h) Modular so one can use multiple units to do simultaneous comparison of
more than two oscillators.
i) Isolation between D/M and counter so that the counter can be powered
by the PC USB port
I am happy to report that all goals have been accomplished, attached is a
picture of the D/M, limitation of the file size does not allow me to attach
an actual board picture, but if you contact me direct I will send you one,
the final board is actually nicer since the first layout had to accommodate
The D/M part leans heavy on the original NIST unit with a few substitutions
and recommendations from Bob Camp. Also beside Opto Couplers SN65LVDS1's
have been included for those that want to use other counting methods.
Selection of filter capacitors allow the use at other offset frequencies such as
10 and 100 Hz. The D/M fits in a standard 74 X 111 X 20 mm Euro case and
the counter can be stacked below or next to it using the Opto Isolators as
the inter connect. The SYPD-1's fit right on the board but connections are
included to use the HP 10514 A. As a matter of fact removing the HP mixer
board from its housing fits it nicely on the board and every thing is still
inside the housing.
The counter will handle 1 an 10 Hz offset with a 1 E 14 resolution at 10
Hz. Thanks to Richard Mc Corkle we have great drawings and code, available to
Code, drawings, list of material and PC board layouts and its file, will
be available to every one once the project is completed.
I need help in the following areas
a) help me create a nice set of drawings that are computer generated
something I am not able to do
b) create the computer program that takes the output of the counter board
and allows Allan Variance plots, frequency difference and dual temperature
readings and plots using RS232 and USB.
c) an independent test by a third party.
As I said previously, I am not getting in the business of supplying parts
but will work with people that will help achieve the three points listed
above. Presently I have boards on order and will have two uncommitted board
sets and probably also component kits.
Please contact me directly.
Again thank you Corby Dawson, Richard Mc Corkle and Bob Camp.
Bert Kehren Miami
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