[time-nuts] Dual Mixer
warrensjmail-one at yahoo.com
Tue May 11 17:46:57 UTC 2010
For the Really cheap time nuts,
It sounds like Bert Kehren has done a great Job building a Dual Mixer
There are other simpler, less standard ways to get good data for Allan
Variance and small frequency differences.
My VERY simple $10.00 analog tight PLL Tester BB (Previoulsy posted) pretty
much accomplishes the same goals as his,
and it can do 1e-13 in a second, and 1e-11 in 10ms (limited of course by
the single reference Oscillator used)
A simple test that most can do at home, and still challenges the best high
end testers out there is Tom's the swinging Oscillator test.
(The results from my PLL tester is attached)
----- Original Message -----
From: <EWKehren at aol.com>
To: <time-nuts at febo.com>
Sent: Tuesday, May 11, 2010 7:02 AM
Subject: [time-nuts] Dual Mixer
> 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
> 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
> an actual board picture, but if you contact me direct I will send you
> 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
> 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
> the inter connect. The SYPD-1's fit right on the board but connections
> 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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