Yes, Iowa’s radar was far more advanced than Yamato’s. In fact, the Japanese never had a dedicated fire-control radar. It’s possible that Yamato did generate FC data via radar at Samar, but if it came to that, Iowa had countermeasures and I don’t believe Yamato had any.
Nuke1 has an important point, and to go a step further, radar doesn’t necessarily need incoming fire to knock it out; outgoing can do the job just as effectively.
Some time ago, Norman Friedman wrote an article for USNI Proceedings in which he argued that Iowa was to be favored over Yamato in a gunfight. So who ya gonna believe, me or the most respected battleship researcher in America? (I have to find a better way to word that.) Actually Friedman’s essay shows the bent that routinely skews the Iowa-v-Yamato hypotheticals in Iowa’s favor. It chooses a scenario that plays entirely to Iowa’s strengths and then assumes that matters proceed without a glitch.