This matched pair of milspec Chatham Electronics 6H6 / JAN-CAHG-6H6-WGT tubes was tested on our Paul Hart-calibrated TV7/U for shorts, gas and transconductance. There were no shorts or gas..
Tube One measured 49/49 while Tube Two measured 51/51 where minimum (65%) is 40/40 and 100% is 62/62.
These tubes are very-well-built and extremely-rugged. They have an extra mica spacer for vibration suppression, thick glass and micanol bases.