Offered is a lot of (12) 12SA7 Pentagrid Converter tubes, by RCA. The tubes all test Good on the EICO dynamic tester and they show no shorts or inter-element leakage.  (3) have early logos, (1) is a JAN-CRC-12SA7 type, (7) have new logos and one is branded Cunningham. Used in Series String radios from the 1930's up to the 1950's.  Pick up the lot of RCA 12SA7 tubes for your own stock for work upcoming or for something on the bench right now. US Made.  NO RESERVE!! Thanks for looking.