As used in the Elecraft KPA-1500 (two of them, which gives a great deal of overhead).
And I do have CK-722's. They came in a small plastic case I purchased at the Radio Shack in 100 Oaks Mall in Nashville, TN back in the early 70's. There were a small quantity of Silicon NPN and PNP and Germanium NPN and PNP transistors.
I bought it to complete my first attempted homebrew receiver project which was a regnerative receiver for 40M. Never did get that thing to work, and I progressed from there to building a Heathkit HW-101 using my saved-up lawn-mowning money.
My Novice station was a used Hallicrafters SX-99U with outboard Heathkit Q-Multiplier, and a borrowed Knightkit T-60.
Hey, do you think we'll get a surface-mount 4CX1500?
Jim, I have a single GE-2 that I'll trade you for a good 4CX1500. Might get a watt out of it in pulse service. I did have an AM amp using pulse rated 4-1000A's a couple decades ago. One RF amp, the other cathode modulated the top tube. Modulation transformers were much more expensive than the tubes.
I digress. I never owned a CK-722 but thought they looked neat.