[time-nuts] Dual Mixer
szeker.k at gmail.com
Tue May 11 14:56:38 UTC 2010
I can help you in PCAD schema drowing(i.e. as xxx.pdf output too)_have a
litle experiance :-).
(so ca. 20 years, & with RF layouting so good 30 years)...
2010/5/11 <EWKehren at aol.com>
> 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
> several variances.
> 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
> 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
> every one.
> 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
> 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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