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[time-freq] Reflock II N divisor question for 10 MHzref114.200MHz Fin

Luis Cupido cupido at mail.ua.pt
Wed Aug 9 11:40:18 UTC 2006


Good.

Don't forget to optimize your loop filter for lowest phase noise
if that is of relevance for you, since you're using a VCO it makes
all the sense to invest some time there.

Luis Cupido
CT1DMK.


  ----- Original Message ----- 
  From: Mike Suhar 
  To: 'TAPR time and frequency projects' 
  Sent: Wednesday, August 09, 2006 4:08 AM
  Subject: RE: [time-freq] Reflock II N divisor question for 10 MHzref114.200MHz Fin


  That did the trick.  I had to increase the value of R22 on the op-amp to get a little higher tuning voltage.  Around 17K gave me the 4.05 volts I needed.  The original 10K was just a little shy.  The VCO is now singing along at 114.200 000 Mhz

   

  Mike

  .

   


------------------------------------------------------------------------------

  From: time-freq-bounces at lists.tapr.org [mailto:time-freq-bounces at lists.tapr.org] On Behalf Of Luis Cupido
  Sent: Tuesday, August 08, 2006 7:26 AM
  To: TAPR time and frequency projects
  Subject: Re: [time-freq] Reflock II N divisor question for 10 MHz ref114.200MHz Fin

   

  Hi Mike,

   

  For 114.2MHz the configuration is

  R=50 >> 100

  and 

  N=570 >> 100111010

   

  with fcomp=200kHz which is better than 100kHz for loop performance

  and will allow a wider loop filter etc.

   

  Luis Cupido.

  CT1DMK.

   

    ----- Original Message ----- 

    From: Mike Suhar 

    To: time-freq at lists.tapr.org 

    Sent: Tuesday, August 08, 2006 4:13 AM

    Subject: [time-freq] Reflock II N divisor question for 10 MHz ref 114.200MHz Fin

     

    I am working on the Reflock II board using a 10-MHz reference.  That being the case it appears I need to load the r2_flex_01.pof file.  I did that and now it comes to setting the jumpers.  The "txt" file shows 3-bits are used for the R divisor so I set 000 for 100 KHz.  For N I think I have a problem.  The frequency I need is 114.2 MHz.  That would be N = 1141 considering the N+1.  From the txt file it looks like only 10-bits are being used.  If so, the highest I can go is 1023 + 1 = 102.400 MHz?  

     

    To test out my understanding of the jumpers I set N to 1017 which locked the VCO at 101.800 MHz.  

     

    Mike

    WB8GXB

     


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