[time-nuts] FE-5680A Mechanical Question

EWKehren at aol.com EWKehren at aol.com
Fri Jan 13 06:19:52 EST 2012


What we know is that you can set the Rb in 7 E-13. Dithering would allow  
even closer setting, the question is what rate will the Rb accept with out  
loosing lock or deterioration of the performance. Some one should explore 
that.  I am still waiting to se some aging. Taking the 10 MHz output and than 
use an  analog loop and something like a Morion OCXO and you have the best of 
all.
Digitally controlling the Rb will cut the cost of the control loop in half. 
 For $10 in parts and a PC board for less than $10 using Shera like 
controller  can be realized. What is needed is some one able to do the PIC.
If some one is interested and able, please contact me off list. A low cost  
GPS or a 1 pps output of a Tbolt be perfect source.
Bert Kehren
 
 
In a message dated 1/12/2012 12:20:15 P.M. Eastern Standard Time,  
lists at rtty.us writes:

Hi

I think it would be worth the effort to try dithering the  DDS commands into
the Rb while measuring ADEV. You *might* find that you  can do it with 
little
or no impact on the unit's stability. If so it takes  out some modification
effort and should make the controller cheaper.  

Bob

-----Original Message-----
From:  time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of  EWKehren at aol.com
Sent: Thursday, January 12, 2012 10:43 AM
To:  time-nuts at febo.com
Subject: Re: [time-nuts] FE-5680A Mechanical  Question

Bringing out the C field in my estimation does not effect long  or short  
term. External magnetic field I think is a joke. An other  option is a loop 
that  generates a tuning word for the DDS but that  means your steps are 7
E-13.
Bert Kehren


In a message dated  1/12/2012 10:34:10 A.M. Eastern Standard Time,  
davidwhess at gmail.com  writes:

I was  more interested in the technical details of how to  adjust the
output of a  RbO without sacrificing the short and long  term stability.
I have seen a  few designs that used a DDS to generate  the 10 MHz
output which lends  itself to this but they all suffer from  DDS and
tuning noise.  I see  now that the RbO can be adjusted  with an external
magnetic field.

On  Thu, 12 Jan 2012 07:34:44  -0600, "J. L. Trantham"   <jltran at att.net>
wrote:

>David,
>
>I have  been  following discussions on the list about a GPSDRbO for a year 
  
or
>so.  Some interesting challenges and probably best  implemented  in a 
'stable'
>environment rather than portable  operation but as best I  can tell, it 
would
>require a very  stable and good antenna location,  stable and clean power, 
 
and
>I was thinking of using something like an  LPRO-101 with  an Ext C Field
>input, a Shera type controller, and a GPS  timing  receiver, though, I 
suspect
>there are likely to be some   'multi-tasking' receivers out there that will
>look at several  sources  including GPS, GLOSNASS, etc.
>
>While the project  might be fun,  for portable work, it is likely far 
easier
>and  probably just as good  (almost), to use a Tbolt.
>
>In any  event, something to think  about for the  future.
>
>Joe
>
>-----Original   Message-----
>From: time-nuts-bounces at febo.com   [mailto:time-nuts-bounces at febo.com] On
>Behalf Of  David
>Sent:  Wednesday, January 11, 2012 11:12 PM
>To:  Discussion of precise time and  frequency measurement
>Subject: Re:  [time-nuts] FE-5680A Mechanical  Question
>
>
>How  would a GPSDRbO work?  Phase lock the  DDS output to the GPS? Phase  
lock
>a VCXO to the GPS and then phase lock  to the RbO on loss  of GPS lock?
>
>On Wed, 11 Jan 2012 22:55:58  -0600, "J. L.  Trantham"  <jltran at att.net>
>wrote:
>
>>Bill,  Brian, Bill, and  Peter,
>>
>>Thanks for the  info.  All I need now is a  'project' to incorporate the  
>>unit into.
>>
>>In  the back of my mind, I  have the thought of a 'box' that will be  
>>battery powered or  110 VAC powered (perhaps with an internal SLA  
>>battery) and  include a GPSDO and Rb unit (possibly a GPSDRbO) for  the  
>>purpose of a 'reference' for portable operation in the   microwave   
>>regions.
>
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