[time-nuts] oscillator choice question (ND100M)

chris at yipyap.com chris at yipyap.com
Mon May 3 20:02:04 UTC 2010

just for show-and-tell:

I've been disassembling the Schmomandl ND100M oscillator
block to see if I could use it.  I figured, it's the bird
in hand, and once was a high quality piece of equipment
so maybe...

The physical construction is great.  Lots of fine pitch
slot head machine screws.  Lots of silver plating.

The oscillator unit is long and narrow.  It goes
in the 19" rack mount unit in the "depth" direction,
front to back in the upper left hand corner of what
turns out to be a more or less solid block of plated
boxes that make up the whole frequency generator.
Decade controls on the front are switches only.  Each
is wired to a decade unit/card and the decade units are
fed signal all in series.  Computerish connectors
at the back reproduce the decade switches in some
manner, so the thing can be remotely controlled
for frequency output.

I have four rough pictures.

www.yipyap.com/radio_stuff/ND100M/One.pdf  is right (rear)
end of the component side.

www.yipyap.com/radio_stuff/ND100M/Four.pdf is the left (front)
end of the component side.

www.yipyap.com/radio_stuff/ND100M/Two.pdf is a blurry closeup
of the center from the trace side.

www.yipyap.com/radio_stuff/ND100M/Three.pdf shows the
power connector  (+13.6, -11), two series resistors on those
power lines, and 8 output lines.  Some of the outputs are
10 Mhz.  At least one is 1 Mhz.

The center crystal cannister is electrically isolated.
It is on acrylic stand offs.  Even the trimmer control
uses a smaller acrylic rod within a larger acrylic
tube/standoff.  And the L-shaped piece directly to
the right of the cannister, from which it is supported, is
itself on long standoffs from the right end piece.
There are 3 sets of 4 fine wires coming
out of the crystal cannister, two go to the little board
on the right, one goes to the larger board on the left
(the output board).  The crystal cannister was surrounded
with  white extruded foam of the same kind as a cheap
picnic cooler.

I removed some of the silver "fingers" around the
crystal cannister area to remove the insulation.

I don't know what the board on the right end does.. maybe
temperature control?  The board on the left end seems to be
output buffer/filter.

I don't think I am going to tear this down any further,
and I also don't think I see any easy way for me to adjust
the frequency electronically without ripping into the
crystal cannister and I don't trust my ability to
put it back together in working order.

If you all have suggestions otherwise, fire away.


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