[time-nuts] Morion MV89 output level?

Don @ True-Cal True-Cal at swbell.net
Fri Feb 10 20:34:41 UTC 2012

I've tried both the MV89a and the Oscilloquartz 8663 (I think UCT is the same or very close) with the Thunderbolt. The Oscilloquartz does not fit any of the OCXO thru-hole combinations but the MV89a does fit one of the OCXO variations that TB accommodates. That makes for a very clean/compact replacement for the standard TB oscillator. You have to be soooo careful when wiring an OCXO off-board for ground bounce and other minute disturbances to the EFC. The MV89a as a TB on-board replacement is the only way I could get superb PPT stability out to TC=1000 sec. Even without active disciplining, either oscillator has very good long-term stability.

I have a related question, probably directed to Said, on the Fury OEM board. The MV89a seems to work ok at 10.5 V and draws ~970ma on warm-up, settling out at ~350ma at this lower supply voltage. Is that initial current draw excessive for the Fury OCXO supply? I would like to use the on-board supply so the current draw can provide the feedback for TEMPCO. I'm using NTC thermistors strapped to the OCXO case otherwise like I have done with an 10811. The current approach would seem much better correlated.

  ----- Original Message ----- 
  From: John Miles 
  To: 'Discussion of precise time and frequency measurement' 
  Sent: Friday, February 10, 2012 3:28 AM
  Subject: Re: [time-nuts] Morion MV89 output level?

  > Did you ever run any tests on those UCT double oven OCXOs?   

  Only to the extent of running a short (10-minute) HDEV test after a ~2 hour
  warmup, to see if it was capable of anything interesting near t=10s to
  t=30s.  It showed about 2E-12, and the PN was nothing special, so I didn't
  do anything else with it.  I'll leave one running for a few days and try it.

  >I've found
  > them to be freaky-stable long term.   I have retrofitted a lot of Tek
  > DC510/5010 counters with them and after over two years,  the last digit is
  > still right on.

  They would probably be good for homebrew GPSDOs, given their small size.
  Perhaps a Thunderbolt refit.

  -- john

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