MRF1K50H is the name of the latest and greatest LDMOS RF part that comes out of the NXP laboratories. It is a small piece of electronics history in itself, being the most powerful transistor ever created in any technology, at any frequency (actually, it's a pair of transistors inside the MRF1K50H, but still applies). It has an output power of 1500W, works at 50V and up to 500MHz, typical effciency is 74% in AB class and the gain is 23.5dB @ 230MHz. There is also another version available called MRF1K50N that has marginally lower gain and efficiency, but compensates with a (30%) lower thermal resistance.
Both of these parts can withstand 65:1 SWR and are drop-in replacements for previous LDMOS models (such as the MRFE6VP61K25H or BLF188).
And as I mention those two names, I'm sure some of you heard a small bell ringing: wait a minute, MRFE6VP61K25H is a Freescale part while BLF188 is a NXP part, so how come the new MRF1K50H NXP part has such a Freescale-like name ? Well, the news is that at the end of 2015 Freescale and NXP merged, so this is probably the first fruit of their young love. If you're wondering what happened to the BLFxxx line of products, they ended up under the chinese-owned Ampleon brand, together with most of NXP's RF business unit.