3a3 hv rectifier tube

[Red Raster]

At the risk of being scorned, laughed at or booted off the forum, I do a ping test, while holding the base of the hv rect tube i flick a finger striking the envolope, if the ping has sharp ring to it i have always found the tube to be good and bad if the ring sound is muffled and dull with a loose rattle. For those using solid state hv rectifiers i test them using 110vac in series with a neon bulb and if one pole of the neon bulb is lit the rectifier is good.