Designing a DC block for a spectrum analyzer for power supply noise measurements

[jonpaul]

Bonjour matthuszagh

1/ P6201: BEWARE, the FET probes  input V is limited and the FET will have a gate damage if the spec is exceeded even for nanoseconds. We have these but use with great caution and precautions.

So, I have NEVER used P6201 for PSU testing.

Beware that a P6201 on Ebay may have gate damaged, the seller will not know.
It MUST have all the tips, attenuators, etc to be useful. We have found them useable IF like new and never used.
The active FET probes require power  15/-15 V PS from a TEK Lemo 4 pin probe power connector (found on some old scopes and separate PSU 1103)
You can DIY the PSU, but the Lemo connector is not so easy.

Check the P6201 manual and TEKwiki. https://w140.com/tekwiki/wiki/P6201

2/ Jim Williams: Old friend and Analog Guru, since 1970s. Used to see him at Lin tech, Ham fleas and AES conventions, also with his friend Bob PEASE.
JW  books and articles are a goldmine of info.
https://en.wikipedia.org/wiki/Jim_Williams_(analog_designer)
Sad days when they both passed away a decade ago...

3/ Hewlett Packard: The old HP/Agilent App notes are another goldmine of info: These decades old notes are classics, and will clear most of your questions.
https://www.hpmemoryproject.org/ressources/resrc_an_01.htm

in particular see the excellent Agilent AN 372-1  "Power Supply Testing"
http://ridl.cfd.rit.edu/products/manuals/Agilent/power%20supplies/CD1/Literature/5952-4190.pdf

Je vous souhaite un bon apprentissage des techniques d'alimentation électronique !

Bonne journée,

Jon