Bonjour, we have worked for decades with TEK CAL, have 7104, 7904, many 2465B.
Rather than CAL of freq resp, we find the transient response adjustments most critical and that a linearity check and adjustment is also required.
The groups.io TekScopes group has many threads on the topic of CAL generators and scope CAL.
1/ You can easily solve the HF leveled with HP RF gens like the classic Cavity gen 8640B 500 kHx...512 or 1024 MHz. . You can find at Ham fleas, heavy to ship on epay.
2/ We use SG 503 up to 250 MHz, we never got a good SG504 with level head.
The excellent TEK CAL set is TG501/A Time Mark gen
https://w140.com/tekwiki/wiki/TG501and PG506, Calibration Gen.
https://w140.com/tekwiki/wiki/PG506Finally the rare and excellent (but flaky elastomeric switches!) TEK 7000 CAL fixtures 067-0587-01 (7904 500 MHz) and -02 (1 GHz 7104)
https://w140.com/tekwiki/wiki/067-0587-013/ For transient CAL an alt to the usual pulse gens and PG506 is the amazing Leo Bodnar 40 pS pulse, a tiny board with aBNC that fits direct on the 50 Ohm input of a DUT.
Just L50!
http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=295I hope this proves useful,
Bon courage!
Jon