| Electronics > Beginners |
| Why are spectrum analyzers so expensive? |
| << < (8/9) > >> |
| bd139:
http://hfsignals.blogspot.com/p/specan-reboot-of-w7zoi.html?m=1 |
| JohnPen:
For those of an adventurist nature you could build a Scotties Spectrum analyser. However it is not that cheap, because of component costs, and takes quite a while to build. Also sourcing suitable VCO chips has become more complicated as Minicircuit's no longer make the VCO chips. It is still cheaper than purchasing a Rigol or Siglent and you learn a lot but it is a somewhat long term construction project. :) However reading through Scottie's site provides a lot of useful information on understanding and building your own Spectrum analyser. There is also a dedicated Yahoo group, see below, which provides great support for those who bite the bullet. http://scottyspectrumanalyzer.us/ https://groups.yahoo.com/neo/groups/spectrumanalyzer/conversations/messages |
| RoGeorge:
--- Quote from: T3sl4co1l on June 10, 2019, 06:14:01 am ---On a related note, I wonder if anyone ever tried making, say, a tunable quartz or mechanical filter, that uses a stretchy or bendy substrate as resonator, so that the dominant mode can be varied over a modest range. --- End quote --- That was exactly my thought, too. To experiment with a decapped Quartz by pressing it in a vice with rubber jaws, and see how much the resonant frequency can be shifted without snapping the crystal. If it would be enough, the next step would be to replace the vice with some piezo material in order to electrically control the mechanical pressure, and thus the resonant frequency. ;D Most probably this idea was already tested before, and the results were nothing spectacular, so we don't have today such a device commercially available, but still, it will be an interesting experiment to tinker with. :-DMM |
| ebastler:
--- Quote from: RoGeorge on June 10, 2019, 08:28:49 am --- --- Quote from: T3sl4co1l on June 10, 2019, 06:14:01 am ---On a related note, I wonder if anyone ever tried making, say, a tunable quartz or mechanical filter, that uses a stretchy or bendy substrate as resonator, so that the dominant mode can be varied over a modest range. --- End quote --- That was exactly my thought, too. To experiment with a decapped Quartz by pressing it in a vice with rubber jaws, and see how much the resonant frequency can be shifted without snapping the crystal. If it would be enough, the next step would be to replace the vice with some piezo material in order to electrically control the mechanical pressure, and thus the resonant frequency. ;D Most probably this idea was already tested before, and the results were nothing spectacular, so we don't have today such a device commercially available, but still, it will be an interesting experiment to tinker with. :-DMM --- End quote --- My gut feeling is that this would provide a small tuning range and bad frequency stabilty (since the inherent stability of the quartz crystal is compromised by external, macroscopic mechanisms which will be affected by temeperature drift, vibration etc.). The worst of both worlds. ;) |
| IDEngineer:
--- Quote from: T3sl4co1l on June 10, 2019, 01:47:38 am ---In any case the important part is not yttrium, it's that it's a garnet made with iron, and yttrium happens to be necessary to make that happen. And then that the result is magnetically tuned, yes. --- End quote --- I've studied YIG's for quite a while as a sort of side interest. Like the other respondent(s), it still feels like the stuff of science-fiction. Kinda like "red matter" in Star Trek or that beryllium time-travel device in Galaxy Quest. "Captain, we can't increase the field through the YIG sphere! We're already past the redline! Nobody's ever even tried to go this far before!" IIRC, the magnetically tunable behavior is believed to result from the asymmetric location of two of the Fe atoms in the crystalline matrix. It took me a while to learn that. For a long time I thought it was due to the yttrium content, because in many applications yttrium behaves a lot like a rare earth - which have consistent outer shells and differ by how their 4f shells are filled, giving rise to their similar chemical behavior yet differing magnetic behavior. However, in the case of YIG, your comments appear spot-on... what's needed is a crystalline matrix that asymmetrically positions the Fe atoms and Y+I does that. The one thing I haven't been able to discover is who the heck originally figured this out - or even conceived of the concept that properly, asymmetrically positioned Fe atoms would yield magnetically tunable resonance in a physical object, with linear response to boot. That's a person or team I'd like to know more about. What the heck else did they do that doesn't get enough publicity? |
| Navigation |
| Message Index |
| Next page |
| Previous page |