[time-nuts] Trimble GPS board

Bob Benward rbenward at verizon.net
Sun Aug 23 22:55:35 EDT 2015

You are correct, I missed that regulator, but may other Trimble oscillators
are powered by +12V.  That's what led me down the wrong path.  I still
suspect that it might have been designed for +12V, as +6.5V is not a common
supply rail.

I just got my Trimble board yesterday and hope to have it running this week.
I am still wrestling with my Z3801, trying to get it to run with a Morion
MV89, but then that crapped out.  Now trying to get it to work with a
Efratom OCXO.


>>> -----Original Message-----
>>> From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Arthur
>>> Dent
>>> Sent: Saturday, August 22, 2015 6:25 PM
>>> To: time-nuts at febo.com
>>> Subject: [time-nuts] Trimble GPS board
>>> rbenward at verizon.net wrote: "See below, here is a 73090 OCXO (same as
>>> on some of those GPSDO boards) powered by +12V."
>>> You are incorrect in your assumption that the link you have supplied
shows a
>>> 73090 OCXO powered by +12VDC. The BOARD is indeed powered by 12VDC
>>> (or 15VDC if you read the listing) but if you look at all the photos you
will see
>>> a 3-terminal regulator on the bottom of the pc board.
>>> The Trimble GPSDO I'm supplying 6.3VDC to had a 5 volt regulator that
has a
>>> measured output of 5.00VDC and the supply pin on the oscillator had that
>>> 5.00VDC on it, not the 6.3VDC from my supply.
>>> A continuity check shows a direct connection from the regulator's
>>> 5 volt output directly to the oscillator's supply pin. Because of the
>>> current drawn by the 5 volt oven, running the input to the board at
>>> and wasting all that power as heat would not be wise. 6.3VDC makes me
>>> happy and they chose a LDO regulator for a good reason.
>>> The one error I did notice is I said the board locked after it found
satellites but
>>> that is incorrect. It does find satellites quickly but takes about 10
minutes to
>>> lock and that is when the 10Mhz output is enabled. I did some of my
>>> checking around 1AM and that is not a good time for clear thinking or
>>> writing.
>>> -Arthur
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