Hi There certainly are fundamental SC’s out there.
SC’s typically have motional resistances above 50 ohms. This usually makes transmission a better way to look for this or that resonance than impedance. Bob > On Feb 25, 2020, at 7:42 PM, Gerhard Hoffmann via time-nuts > <[email protected]> wrote: > > I had a Morion MV89A that would stop oscillating when Vtune was more than > +600 mV. > > So I cut it open to recover at least the crystal, for own experiments. > > Pics are there: > > < > https://www.flickr.com/photos/137684711@N07/49585174873/in/album-72157662535945536/ > > > > and then following the right arrow. > > > To get a first impression, I soldered the crystal to an SMA plug and put it > on an > > R&S ZVB-8 network analyzer and measured S11. I could see the 5 MHz resonance > > as a 15 dB dip. There was also a resonance at 5.45 and a smaller one another > 90 KHz > > higher. the +10% suggest that it is an SC cut. > > But I could not see anything at 1 or 1.6666 MHz, so it should be a > fundamental crystal? > > Is that common? > > I made most measurements at room temperature. I can turn the hot air solder > > station down to 91°C which is not far away from the crystal's 87.7°C > > inflection point, and I could see some variation on the 5.45 MHz resonance > vs. temp. > > I must build a fixture for the hot air because the sweep time at 1 Hz > bandwidth > > is close to eternal. > > > Is the un-harmonicity (???) between fundamental and overtones stronger with > SC-cuts > > than normal AT? I also could not see anything at 15 MHz. Next I'll make a > board > > for the PI fixture as described by Bernd Neubig in his crystal cookbook. > > > BTW I could see some more dips with >= 10 Hz resolution. I hope that does not > mean > > that the ZVB needs service. > > > cheers, Gerhard > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
