[R-390] 17 MHz Crystal

[Bob Camp]

Hi

In a crystal like the one shown the frequency is determined by the thickness. That's generally true of any crystal in the > 1 MHz frequency range. To make things work ( Q / resistance / trim range) you need a thickness to diameter ratio > 100. That all gets impractical as you go down in frequency, so you go to cuts that resonate in other ways.

Bob

On May 14, 2013, at 8:50 PM, Barry <n4buq at knology.net> wrote:

> So, it's the thickness that matters more than overall size, correct?
> Barry - N4BUQ
> 
> Sent from my iPad
> 
> On May 14, 2013, at 7:11 PM, Bob Camp <ham at kb8tq.com> wrote:
> 
>> Hi
>> 
>> Actually it's still two 17 MHz crystals. A jumper from the unconnected post to the unconnected electrode likely would get it to oscillate (sort of). By the way, I'm not in any way suggesting doing this.
>> 
>> Bob
>> 
>> On May 14, 2013, at 3:51 PM, Barry <n4buq at knology.net> wrote:
>> 
>>> Technically, I suppose that would be two 34MHz crystals...
>>> 
>>> Barry - N4BUQ
>>> 
>>>> Maybe you could have two 8.5Mc crystals? <grin>
>>>> 
>>>> BTW, I did have a 17.000 but a previous owner wrote 16.996 on it.  It
>>>> would probably have worked, though.
>>>> 
>>>> 73,
>>>> Barry - N4BUQ
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