[time-nuts] Valpey-Fisher VFT22H OCXO Output

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sat Jan 30 14:35:34 EST 2016


Waveform is similar to that produced by an inductive input low pass filter with 
all but the first section inoperative when driven by a square wave input.

Bruce
On Saturday, January 30, 2016 09:33:45 AM Bob Camp wrote:
> Hi
> 
> Unless it’s a really weird termination impedance, it’s broke. The SMA is a
> pretty good indication that it *should* work into a 50 ohm load.
> 
> The only other possibility is that your probe is taking the load far enough
> off of 50 ohms to mis-tune the output filter. I’d set the scope to 50 ohm
> input and cabe the output directly to it. If that’s not practical, put a 6
> db 50 ohm pad on the output of the oscillator and see what it looks like
> after that.
> 
> Bob
> 
> > On Jan 29, 2016, at 10:19 PM, Logan Cummings <logan.cummings at gmail.com>
> > wrote:
> > 
> > Hi All,
> > 
> >     Curious what could give this waveform (attached) - I presume this is
> > 
> > not correct output for this oscillator (surplus/salvage from Harris
> > Constellation receiver).
> > 
> >     Frequency looks OK with +2V EFC but output looks like neither sine nor
> > 
> > any CMOS I've seen into 10Mohm (first capture, scope probe alone) or 50ohm
> > (50ohm term at SMA connector, probed by same scope probe) .
> > 
> >     What gives? If I open up the can, what am I looking to possibly
> > 
> > replace/eliminate? How to open it? It's soldered shut (2x2in case).
> > 
> >     I need a good low-noise 100MHz sine wave for my application so I'm
> > 
> > tempted to open this guy up and replace the output circuitry with
> > something
> > more suitable.
> > 
> >    Thanks in advance for any pointers/info on these units!
> > 
> > -Logan
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