> The problem is modulation of the reference signal via relative > movement of the transformer guts.  While I understand there are ways > to 'harden' magnetic devices, my application is far too sensitive to > even consider a magnetic approach given the availability of > alternatives.  Any spurious signals present on the 10 MHz reference > will be increased by 56 dB by the phase-locked loop. Capacitors are piezoelectric too. Does anybodyhave any handy numbers for this sort of stuff? -- These are my opinions, not necessarily my employer's. I hate spam.

Hi Vibration modulates lead inductance. That's true even on SMT semiconductors.. It's true big time for leaded parts of the axial persuasion. Weather the amount of change matters to you is another thing entirely. If you stick with NPO even for the bypass caps, the piezo stuff is not going to be a big issue. Bob On Feb 18, 2010, at 5:48 PM, Hal Murray wrote: > >> The problem is modulation of the reference signal via relative >> movement of the transformer guts. While I understand there are ways >> to 'harden' magnetic devices, my application is far too sensitive to >> even consider a magnetic approach given the availability of >> alternatives. Any spurious signals present on the 10 MHz reference >> will be increased by 56 dB by the phase-locked loop. > > Capacitors are piezoelectric too. > > Does anybodyhave any handy numbers for this sort of stuff? > > > -- > These are my opinions, not necessarily my employer's. I hate spam. > > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. >

Hal Murray wrote: > >> The problem is modulation of the reference signal via relative >> movement of the transformer guts. While I understand there are ways >> to 'harden' magnetic devices, my application is far too sensitive to >> even consider a magnetic approach given the availability of >> alternatives. Any spurious signals present on the 10 MHz reference >> will be increased by 56 dB by the phase-locked loop. >> > Capacitors are piezoelectric too. > > Does anybodyhave any handy numbers for this sort of stuff? > > > Most high K ceramic caps are ferroelectric below the Curie temperature and paraelectic above that. The resultant capacitance nonlinearity can allow low frequency noise to phase modulate a capacitor coupled RF signal if the phase shift due to the capacitor is sufficiently large. Yet another reason to avoid high K ceramic capacitors or at least ensure that the RF phase shift due to such capacitors is sufficiently small. Low frequency magnetic fields can phase modulate transformer coupled RF signals by modulating the transformer phase shift. Bruce