|JRC stands for Japan Radio Company. They are an industrial electronics company. We were a JRC Sales and Service Center and sold several JRC radars to the local marine industry. Mostly to work boats. However, this particular group of tubes came from RF Gain or Richardson.|
I don't recall the model numbers but many popular models of Raytheon, Apelco and other brand marine radars of the era were nothing but private labeled JRCs.