1 ea  U30  Vacuum Full-wave Rectifier Radio Tube 30s RARE,  filaments illuminate; no mfr markings, except U30 engraved on base.  This tube came from a lot of tubes bought from England.  None of my tube testers will test this PN, but filaments light up with 26 vac.  Since I cannot fully test this tube, sold as is with no return.