Well, what a special device, essentially a U52 mounted on a UX4 base, this is a superb valve indeed. Badged in green base print as a Sylvania this is scarce and desirable too.
Showing perfect emission on test, will you give it a home?
The 5Z3 is a high power rectifier and was typically used in small radio transmitters, high power audio amplifiers, and modulators for amplitude modulation (AM) transmitters. Much like the famed U52, the filaments are inverted 'v's of coated ribbon. The valve is mounted on a UX4 base pins, The type 5Z3 was first marketed and sold in 1936.
