The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator

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#3,142
1audio said:
The best low frequency shields are magnetic. Mumetal works well but needs to be annealed after fabrication. Steel also works if thick enough. I have seen references to 18 Gauge in the past but that's fuzzy memory. For high frequencies you need conduction. Silver plated copper or brass works very well if there are no holes or slots (sounds like PCB ground plane recommendations). Remember you are both keeping the noise out and the RF in. Use feedthrough caps to connect through the housing, the Wenzel connections shown below are a good example of RF safe connections. The feed through prevents much RF from getting in or out of the enclosure. And try to seal up seams with RF gaskets if you can. Its why the commercial OXCO's are sealed with solder.

I had a really exotic EMI test receiver for a while. The housing was constructed of steel, furnace brazed to seal off of the seams and then silver plated to maximize the shielding. Weighed a ton. It had continuous tuning from 100 KHz to 1.2 GHz so it would be sensitive to anything. Important when you are trying to make sure your secrets are safe from foreign powers.
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Demian,
Do you know what the name of the connectors you have surrounded on the photos?
 
#3,150
Since you don't use the FIFO I refer to the TWTMC-STS-SX.

Input: 50 Ohm sine wave, SMA or u.fl connector (SMA recommended)
Output: 50 Ohm square wave (3V3 CMOS), pin header
Board size: 21mm x 28mm
Power supply: 3.3 Vdc 15 mA

For the connections please see the attached picture.
 

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#3,152
Andrea, thanks for the info.
What output cabling would you advice for the TWTMC-STS-SX ?
Should we use 50 Ohm coax, soldered to the output/GND pads on the STS-board, or shielded twisted pair wire would work as well?

I guess short cabling is best, but how long would you say the output cable can be before there is could be a problem?
 
#3,159
The MOQ for each crystals is specified in the Order Form.

Anyway the MOQ is from 10 to 15 pcs, it depends on crystal type and frequency.

The MOQ is not related to a single order, it's the minimum quantity I have to order to the manufacturer, so the sum of all the orders I will collect for each crystal type have to meet this MOQ.
 
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