Author Topic: Testing crystals  (Read 498 times)

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Offline Dave Turner

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Testing crystals
« on: December 28, 2013, 10:21:08 AM »
A simple question for many I've no doubt.

How do you determine whether an unknown crystal say supposedly 8MHz is viable or not when you don't have an existing proven oscillator to test it as a replacement?

Is the test rig of, say a Pierce oscillator, not working because of the crystal or poor layout or any other reason?

More importantly, using a basic signal generator and oscilloscope one can easily obtain, at least, a rough estimate of capacitance & inductance. Is the same possible for a crystal?

Compliments of the season to all.

Online Rory

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Re: Testing crystals
« Reply #1 on: December 28, 2013, 11:54:39 AM »
When it comes to crystals, there is really no such thing as a simple answer.  If you're looking for a go/no-go tester whcih spits out the frequency, do web search for "crystal tester". Lots of schematics out there. If you want to find out the particular crystal's device parameters, you need to find out how it's done. One name comes immediately to mind: Wes Hayward, W7ZOI. Look up his stuff. Much of what is published today is derived from his work.

Let me point you to a link to get you started... though it is focused on using discrete crystals in bandpass filters, the fundamentals are there.

http://pages.suddenlink.net/wa5bdu/crystal_slide_show.pdf

Offline vk3yedotcom

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Re: Testing crystals
« Reply #2 on: December 28, 2013, 03:17:36 PM »
Wes Hayward's stuff is good.

Or knock up an oscillator like this which works with almost all HF crystals.

Building electronics from schematic diagrams


An RF probe or receiver can be used to verify output.
Radio and simple electronic projects and videos at http://www.vk3ye.com and http://www.youtube.com/vk3ye

Offline Dave Turner

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Re: Testing crystals
« Reply #3 on: December 28, 2013, 09:16:02 PM »
Exactly what I'd been looking for.
Thank You


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