oscillator design with a long xtal lead

Hello Rich,

I was actually thinking about one, a little nuvistor tube. But I didn't post to avoid being pelted.

Regards, Joerg

It'd skip the pcb and mount the components in 3D flying anyway. Extended 200 degrees for outgassing is not really according to the temperature profiles. The only part that can realistically produce vapors is the SOT23, not the coils, nor the ceramic cap.

Rene

Joerg, the whole is a an impedance analyzer, not a low end one though, as the changes to be measures are minute. And the changes are biggest when the oscillator oscillates.

Rene

Contrary to popular belief, the 1m length of cable at 10MHz is a simple lumped element- but a gain swamping one at that. The RG-316 types run ~32pf/foot or about 100pf bulk capacitance in that 1m length, and at Zo=50 ohms, the inductance comes in at 80nh/ft or 240nh over the 1m length.

Yes. I scanned this thread quickly and don't think anyone mentioned changing the oscillator type.

How about using a series resonant oscillator circuit? At resonance the crystal will appear to be a fairly low value resistor and with a bit of luck might even be close to the impedance of the coax, although this isn't a requirement.

If you know the motional parameters you can calculate the effect of the cable on the resonant frequency.

Well, it might not work if the toob is still in its envelope - those frit glass seals are proof against ordinary air, but I don't know what happens if they try to keep vacuum out. ;-)

Thanks! Rich