5U4G, GEC, 10E/373, U52,BLACK BASE, WITH BROKEN SPIGOT, HAMMERSMITH PRODUCTION FOR AIR MINISTRY with ENVELOPE OVERCAP SLEEVE, VT-244, 5U4G, 5U4

5U4G, GEC, 10E/373, U52,BLACK BASE, WITH BROKEN SPIGOT,  HAMMERSMITH PRODUCTION FOR AIR MINISTRY with ENVELOPE OVERCAP SLEEVE, VT-244, 5U4G, 5U4 

This GEC U52 valve shows excellent bright getter and tests as GOOD using my AVO VCM163 valve tester. The black base is tight to the envelope BUT HAS A BROKEN KEYWAY/SPIGOT.  This has no effect on operation apart from care needed to ensure correct alignment when mounting and results in a sizeable discount on price too.  It has both an etched elliptical  cartouche showing GEC manufacture as well as a slightly faded  white Air Ministry markings.

Device test data: Ia = 120.0mA range, GOOD  A1 67 / A2 67.

We test our rectifiers using a calibrated and standardised AVO VCM163 on the specified range.  This VCM gives a qualitative estimation of emission as you can see from the photo, the GOOD range bar runs below the numerical uA/Ig scale with the GOOD range between 51 - 100.  The above device test data, shows the max current range specified and a record of the numerical reading within the GOOD range obtained.