Re: LC oscillator using BUF602

Perhaps. Neither inductor has any parallel capacitance, and L2 hasn't got any series resistance either.

Replacing L1 with a 150n Wurth ferrite bead, which does come with full set of data - the part I picked was 742794 WE-CBF 1806 - stopped it from working.

A YAGEO company - Pulse sells a 150nH part you can buy from Mouser

PE-0603CD151GTT 150 @ 250MHz 28 @ 150MHz 990 0.92 2

The 990 number is the series resonant frequency of 990MHz which implies a parallel capacitance of 17pF. The Q was 28 at 150MHz

Plugging that in, and dropping C1 to 25pF did give a working circuit with a oscillation frequncy of 50.483012MHz.

The second harmonic was 22dB below the fundamental, and the third was

32db down.

A sim is only as good as the component data you plug in.

That wasn't the point. The Wurth ferrite bead is on offer in the LTSpice program with all the parameters you need to model it more or less accurately. There were two other 150nH parts, which I didn't bother trying - ferrite beads are actually intended to kill oscillations (though they don't always succeed ).>

Just one - 99.7MHz. The correct answer is 0.17pF which is remarkably low. It's about the parallel capacitance of an axial resistor.>

Posting an executable program on the web is anti-social. Posting the code which can be compiled into an executable program is more respectable, if the code is properly and accurately commented.

It's a trivial program. I should have checked my calculation before I posted it, but getting it right wouldn't have changed anything.

So why didn't you say so, and plug in the parameters you did have for that part.

I reran the simulation for 35usec - it took ages - and got a much sharper looking Fourier transform, but with the same harmonics.>>

And one thing that screws up engineering really badly is thinking you know what they are, and getting it wrong.

Which can also get you into trouble if you get it wrong.