[Milsurplus] Weird little tube - where was it used?

[David Ross]

I have come up with an RCA 5675 tube.  The data sheet describes it as a 
medium-mu triode  'for cathode-drive applications'.  Rated at full input 
at 1700 Mc, altitudes up to 100,000 feet.

Interesting specs -  does anyone know where this tube was used?

thanks
Dave Ross    N7EPI