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Sets, Parts and Service Information Offered (private sellers only, exact price required, no swaps) You may announce components or sets for sale or offered free here. Private collectors only - no traders. You must include an exact price. No swaps.

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Old 21st Nov 2020, 7:03 pm   #1
dave_n_t
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Default Frequency standard crystals, FOC

I have 4 quartz crystals surplus to requirements.
All are free, apart from postage.
I'll collect interest until COP Tuesday 24th & then use a hat, if needed.


3 X GEC Quartz Crystal Unit type JFC/193 in B7g package; 100 Kc/s +- 6 c/s


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1 X Marconi's Wireless Company Type 1656G/F small glass envelope, wire ended 20000 Kc/s


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(The claimed accuracy of the 100Kc/s units is phenomenal - better than one hundredth of a percent!)


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Old 21st Nov 2020, 7:37 pm   #2
mickm3for
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Default Re: Frequency standard crystals, FOC

could i please go in hat for 1 x 100khz thanks Mick
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Old 22nd Nov 2020, 12:14 am   #3
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Default Re: Frequency standard crystals, FOC

(1/100)% is 100ppm (parts per million)

Routine crystals in cold-weld cases (not soldered) could be done easily at +/-10ppm over 0-70C. TCXOs could get you down to +/-1ppm and are now better still.

David
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Old 22nd Nov 2020, 1:12 am   #4
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Default Re: Frequency standard crystals, FOC

Quote:
Originally Posted by Radio Wrangler View Post
(1/100)% is 100ppm (parts per million)

Routine crystals in cold-weld cases (not soldered) could be done easily at +/-10ppm over 0-70C. TCXOs could get you down to +/-1ppm and are now better still.

David
I do hope that there is no negative inference here about the adequacy for purpose of my Class D wavemeter, with its bakelite crystal housing with rubber gasket .

B
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Old 22nd Nov 2020, 1:25 am   #5
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Default Re: Frequency standard crystals, FOC

It was good enough for its purpose.

In the same era, Bliley corporation put reference crystals for the BC221 in valve housings, evacuated as valves are, and got greater cleanliness and a lot less ageing. The tempco is mostly a function of accurately orienting the cuttong planes at the correct angles to the crystallographic axes.

Materials science and mechanical precision advances have done a lot for crystals, but if you want to adjust the frequency of one with a quick bit of lapping the 10X and FT243 still win.

David
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Old 22nd Nov 2020, 8:23 am   #6
merlinmaxwell
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Default Re: Frequency standard crystals, FOC

The label looks like it says 100kHz +6, not +/- that makes me think it is a calibration mark.
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Old 22nd Nov 2020, 11:48 am   #7
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Default Re: Frequency standard crystals, FOC

Since I have started mucking about with Crystals recently,
I would be interested in a 100Kc one and the 20000Kc.

However, I am happy to go to the back of the Que if others
are interested.



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Old 22nd Nov 2020, 5:32 pm   #8
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Default Re: Frequency standard crystals, FOC

Hi,
if no one else would like one of the 100kc/s one then I would. But I am happy to go to the back of the queue if anyone is interested.. ( as Superscope has put it ).
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Old 22nd Nov 2020, 10:17 pm   #9
Superscope
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Default Re: Frequency standard crystals, FOC

Dam!

I thought I spelt queue wrong!
Now I know I did!






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