The Russian 5Ц4С (5U4S) rectifier is equal to the western 5Z4G and is an upgraded 5Y3. Indirectly heated cathode with peak inverse voltage at 1400v. Slow power up time of 10 seconds.

Manufactured in the Novosibirsk factory during the 70's. Tested on the RoeTest professional computer testing system or Amplitrex AT1000.