I never knew this thread would turn unpleasant, and I can't remember why spending time to post seemed to be a good idea. I have no concern or argument if anyone adds "EMI" caps or not...If it makes you happy, knock yourself out! I just thought it would be helpful to know why you might want to check first to see if it's really required or not before adding extra parts. That was my intention, and maybe that wasn't clear enough.
Don't let it get under the skin, your input is valued here. Nowadays more people seem to expect everything presented for them on the plate, with theory and instructions and explanations that even 5 year old can read. And when you give just a hint you get bashed for not breaking your NDAs and business agreements, with puzzled faces. After all can't please all, there will be always unhappy fella (too expensive, too difficult, too hard to buy parts, no schematics posted, no test result posted, whatever..)
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On my refs (KX with chopper amp and SMT parts, FX with traditional 1013 and THT parts) I saw no positive effects of any additional caps (when modified one of the boards, including additional resistors as Dr.Frank was quite convincing). So as result I did not implement them, keeping design simpler, by the books. I saw no spikes or jumps when good LTZ chip used and proper measurement setup, power source and wiring are used. And my homelab is not some EMI-shielded faraday cage, just a standard apartment with LED lights, monitors, desktop confuser w/o case and bunch of other crap turned on.
Using extra caps or other design changes because of Datron or another company used it before, without rationale why should not be a reason for design engineer to do same in own build. Datron refs even have voodoo slots and VPG networks too, but as we already know, plain 3458A ref works just fine without any of that, providing tempco and stability better than majority of the LTZ builds over these 90 pages.
And approach not to generate EMI instead of patching circuits around to suppress it is the industry standard for decades already. Take any RF equipment, and ask a question, why so many expensive custom made shields around everything, especially around active circuits? Heck, even standard consumer stuff like PC VGA cards, motherboards and peripherals, being as low cost as possible, still usually have ground planes on the edge with via stitching and shielded connectors to reduce emitted EM. Otherwise lot of that stuff would not pass certification and might have trouble selling
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