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[time-freq] Still not there.

Luis Cupido cupido at mail.ua.pt
Mon Aug 28 12:55:31 UTC 2006

Hi Bobby,

>From your description it really looks that
what you think it is the exact 10.000 it is not.
That, according to the 1pps you are feeding in.

it is going down(or up) always until it folds back
just because you are not reaching the right frequency.
it wants to go down (or up) a bit further to the lock
That is what the reflock is telling you.

The leds do lit accordingly, showing what DF/DT
you have.

Your Rb OSC is off frequency for sure.

If you have a VCXO to play with, it would be a good
way to gain practice and to observe the reflock in action
in case you keep having trouble with the Rb osc.

Luis Cupido

  ----- Original Message ----- 
  From: Bobby 
  To: time-freq at lists.tapr.org 
  Sent: Saturday, August 19, 2006 11:41 PM
  Subject: [time-freq] Still not there.

  Hi Luis,

  I've loaded the 30_1 version, but not really much difference.

  LED1 still stays on all the time.
  LED2 now flashes off once every 8 seconds (every few times it waits 15) of so instead of every 15 before.

  The reflockII tune voltage still jumps above the 2 V level (coincides with led2 flashing off) and drifts back down in
  about 0.1V increments each second until it either reaches or passes through the 2V level. Sometimes
  it will smooth out slightly for a few seconds around the 2v level, but then jumps again to about 2.5V 
  when the 8 (or 15 seconds are up). 
  If I choose instead to place the jumper at PD_I instead of PD_N the direction of the steps just reverses,
  everything else remains the same. 

  The 2V level is significant only in that is the tuning voltage my Rb osc is at when it outputs 10000000
  (without the reflock connected) .

  I just changed R22 to 39K and it swings a full volt above the 2V level, but no other change. 
  Perhaps I'm going the wrong way and this is changing too fast for the loop, and a large RC to integrate
  the steps into much slower (or smoother) rate of tuning change is the ticket. Hard to see 8 seconds as
  too fast though.

  Trivia: If I turn off the Rb osc, the reflock tune voltage rails high. Any help there ?

  Any suggestions ?

  73 Bobby   k4bga


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