[time-nuts] Dual Mixer

[WarrenS]

For the Really cheap time nuts,

It sounds like Bert Kehren has done a great Job building a Dual Mixer 
tester.
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.
 http://www.leapsecond.com/pages/10811-g/
(The results from my PLL tester is attached)

ws

******************
----- 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 
> 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
> 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 
> 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
> 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 
> 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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