[time-nuts] Thunderbolt MV-89a OCXO Transplant?

[Bob Camp]

Hi

The MV89A is a 5 MHz resonator doubled to 10 MHz, it will have sub harmonics
that the original OCXO (using a 10 MHz resonator) does not have.

The MV89A has 10 to 20 db worse phase noise as a stand alone OCXO than the
original OCXO. That is masked to some degree by the TBolt's internal noise.

Depending on which MV89A you get (there are many flavors), it's temperature
stability will be 3X to 10X better than the modern versions of the TBolt
OCXO.

The ADEV on the MV89A should be ~2X better than the modern TBolt OCXO.

The tuning voltage range of the original TBolt OCXO is +/- 5V on the MV89
it's 0 to 5V. The pull range on the original is about 5X greater. Both can
be fiddled on the TBolt via LH. 

Check your TBolt board for the connection (if any) to the Vref pin on the
MV89. Shorting it to ground may not be a good thing. Of course your MV89 may
or may not have a voltage on the Vref pin.

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Frederick Bray
Sent: Tuesday, May 28, 2013 10:37 AM
To: time-nuts at febo.com
Subject: [time-nuts] Thunderbolt MV-89a OCXO Transplant?

Looking at the archive, I noticed that several months ago someone 
commented that the Morion MV 89A was a direct replacement for the OCXO 
in the Trimble Thunderbolt in the sense that the Thunderbolt PC board is 
configured to accommodate it.  However, I wasn't able to find further 
details.

I have a spare Thunderbolt and a spare MV89A and I am considering doing 
the transplant.  Before I tear the Thunderbolt apart, I have a few 
questions:

1.  Has anyone actually performed the transplant?  (Does it work?)

2.  Are there any significant drawbacks and advantages to the transplant?

I am aware that the MV 89A may pull more current on the 12 volt line 
than the Trimble and that the original Thunderbolt cover will no longer fit.

Thanks.

Fred Bray

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