U52 OSRAM 10E/373 RAF AIR MINISTRY U52 BLACK BASE WARTIME PRODUCTION
Here we have a single 10E/373 an Air Ministry military specification U52 DIRECTLY HEATED TAPE FILAMENT rectifier manufactured by Osram at their Hammersmith Brook Green factory sometime during the war years.
This valve shows excellent bright getter and has the inverted getter pan situated down by the glass pinch, however, more importantly it tests as EXCELLENT using my Avo VCM163 valve tester. The valve is fitted with the Air Ministry trademark shrink ccollar encircling the envelope and base which was a palliative measure to prevent separation in hiogh altitude applications. This exquisite device carries good white print, the classic U52 envelope shape and the trademark rounded black low loss micanol base - simply super.
Device test data: Ia = 120.0mA for both diode sections.
Device specification 120mA delivery for both diode sections. So you can see we have 100% emission from this venerable beauty.