5U4G U52 OSRAM 10E/373 RAF AIR MINISTRY U52 BLACK BASE WARTIME PRODUCTION MATCHED PAIR
Here we have a matched pair of two Air Ministry 5U4G 10E/373 Air Ministry specification U52 DIRECTLY HEATED TAPE FILAMENT rectifier manufactured by Marconi Osram at their Hammersmith Brook Green factory which carry white inked print
Both valves show excellent bright getter and have the inverted getter pan situated down by the glass pinch, and both test as EXCELLENT using my Avo VCM163 valve tester. The trademark rounded black low loss micanol base is tight to each envelope, however, device A125 has had it's base relied at some time in the past.
Device test data: Ia = 120.0mA for both diode sections in each valve..
Device specification 120mA delivery for both diode sections. So you can see we have 100% emission from this pair of venerable beauties which consititute a sure matched pair.