[time-nuts] Dual Mixer

EWKehren at aol.com EWKehren at aol.com
Tue May 11 18:00:34 UTC 2010

there is no NIH here, please share how you do it for $ 10, I always like to 
 learn, and I have not been a member that long. Is there a link to a 
specific  design?   Thanks Bert
In a message dated 5/11/2010 1:47:15 P.M. Eastern Daylight Time,  
warrensjmail-one at yahoo.com writes:

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) 
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 
> of
> more than two  oscillators.
> i)   Isolation between D/M and counter so that  the counter can be  
> by the PC USB port
> I  am happy to report that all goals have been accomplished, attached is  
> 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 
> 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 
>  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, 
> 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 
> 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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