So i had another swing at the MPSH10 in LT Spice and what it says should happen and what actually is happening are 2 very different things. I got it sorted and it is working fine. But I am not sure if i run with this or revert back to the 2n3904. For now I will run with this and see how it goes, I just have to measure the input and output impedances. Which as of next week or so, will be easier when i have a vna. The circuit is a little different to what was in the schematic in the previous post. I will update the schematic if I end up running with these.

I build this a little different, I had these squares sitting there i made so I used them.

Oscilloscope output, green trace is the signal in, yellow signal out.


Output from the spectrum analyzer.


Oh The Humanity

So i sat here this morning with a bag of 50 crystals playing a game of what is the resonant frequency. Thoroughly boring I can assure you and I am not sure how the ladies at uBitx Labs in India can sort through thousands to get sets of 8. But alas I have done enough for now to get 2 sets that are matched at a guess to within 50hz, being that my frequency counter is only good to 100hz.

One thing that I would not have predicted is the distribution in the resonant frequencies. Its like buck shot, all over the place and the other thing I would not have predicted is the number of dead crystals or ones with so low Q they might as well be dead being 8, that seems like a very high death rate to me. I still have 2 more bags to sort, but thats not happening today, i have 16 matched crystals I need for 2 filters and am moving on to the next thing.