[time-nuts] FE-5680A Mechanical Question

Fri Jan 13 12:48:06 UTC 2012

did a preliminary layout and priced it with expressPCB and in 30 quantity  
the board would cost $ 5 !!!  Any expert willing to volunteer.to do the  
loop?
Bert Kehren

In a message dated 1/13/2012 6:20:25 A.M. Eastern Standard Time,  
EWKehren at aol.com writes:

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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