start with the power supplies, and go on until morning...
Don

On 2018-02-19 16:57, walter shawlee 2 wrote:
I recently got a strange little 1U FEI rack mounted unit called an
FE-7923F-100-1,
which appears to have rear 10MHz and dual 100Mhz outputs. it is called
a Frequency Reference Unit.

sadly, my unit has a fault light, and no outputs. All the internal
supplies look good, and there is an FE-83AA (10.0Mhz) and FE-1020-100
(100Mhz) OCXO inside.  both of these work (when measured at the
oscillators), and seem to have meaningful control including EFC, and I
tracked down the adjustments in a sea of what seem to be prototype
boards next to the oscillators. so, I have two good sources,
adjustable, but still no outputs.
the OCXO signals disappear into a set of boards with no useful
markings as to function, and look mainly digital.

the 100Mhz unit has only about 200mV p-p output, which seems low to
me, the other has lots of signal. I cannot find any data on either
unit on line or at the FEI website, so any data that is out there
would be very welcome, so I can be sure they at least are running
correctly.

I am hoping to use this rack as a source of RF reference signals in
other gear, but clearly I will have to either gut the rest of the
circuitry and add some new buffers, or figure out the rats nest of
hand wiring to determine why it's not working.  any help in that area
hugely appreciated, and I can send pics to anybody interested to know
more about the internals.

the rear apron has AC power in, a 10MHz output SMA, a switch next to
it that says INT/EXT REF. (set to INT), but no way to attach an
external ref.  then there's a D-Sub filtered connector, that runs to
the stacked digital boards, but its purpose is unknown as I cannot see
where the connections go.  there are also two 100Mhz SMA outputs, but
all outputs are dead, with no signal, and the front ONLINE green LED
is dark, and the red FAULT LED is lit. the oscillators do not run to
the rear jacks but disappear into three pcbs.

hoping for some FEI data if anybody has some to share.
all the best,
walter

--
Walter Shawlee 2, President
Sphere Research Corporation
3394 Sunnyside Rd.,  West Kelowna,  BC
V1Z 2V4  CANADA  Phone: (250) 769-1834
walt...@sphere.bc.ca
WS2: We're all in one boat, no matter how it looks to you.
Love is all you need. (John Lennon)
But, that doesn't mean other things don't come in handy. (WS2)

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--
Dr. Don Latham
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304

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