1) I have no previous experience building precision anything, I'm not an expert.
2) My guess is the design expects quality components and depends on the auto calibration to correct any component drift. Short term stability between calibrations is what we want. The absolute value of C16 and C17 is not as important as it's stability in leakage and value. Guess we could put the didoes in a constant temp oven but not sure all the components are more stable at higher temps. Good ideas about didoes here : http://www.sciencebuddies.org/science-fair-projects/project_ideas/Elec_p033.shtml (note Figure 3 and how the didoes voltage drop is more linear at higher temps vs room temp.) Figure 3. Stanley ________________________________ From: Heathkid <heath...@heathkid.com> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Sent: Sat, August 14, 2010 10:43:15 AM Subject: Re: [time-nuts] What's the latest correct PICTIC II Mouserproject?- Heathkid Okay Stanley... I've got a Tektronix 370A curve tracer at work. So the diodes need to be matched? No problem. So I match the diodes and the resistors to within 0.001%. Are there any other components that need matched? Also, you mentioned using hemostats as heatsinks on the diodes while installing them. I know that diodes make very good temperature sensors as well. Are there any suggestions on keeping them stable after they are on the board? What is the recommended operating temperature of the PICTIC II? Thanks. 73 Brice KA8MAV ----- Original Message ----- From: "Stanley Reynolds" <stanley_reyno...@yahoo.com> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Saturday, August 14, 2010 10:43 AM Subject: Re: [time-nuts] What's the latest correct PICTIC II Mouserproject?- Heathkid <snip> Maybe we should buy lots of diodes to match them, they are relative cheap, also use extra care installing them. Using hemostats as heat sinks and just enough heat for a good connection do not want to damage/change them after the match. Stanley _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
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