[time-nuts] Dual Mixer

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


ws
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 
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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