Life span of 5U4G tube?

Anyone know the life span of a vintage 5U4G tube from the 40's or 50's?

spareribs10-23-2008 9:17pm

ontjesr Details Discussions Posts This discussion Message User 157 posts 10-24-2008 at 03:29am Copy Comment URL Report Comment Edit Delete There are no mortuary tables available that I know of.
casouza Details Discussions Posts This discussion Message User 239 posts 10-28-2008 at 06:20am Copy Comment URL Report Comment Edit Delete If your 5U4G is new or NOS, measure the B+ voltage at the HV first power supply cap. I assume you have read the usual safety precautions about dealing with high voltages. Make a note of B+ DC V. If in the future your amp sounds wimpy, check the B+ voltage again. A drop of more than 20 Volts as compared to new specs means that your rectifier is weak (though I have never seen it happen). If you suspect your rectifier to be weak, compare it to a new tube. You can probably expect a 20 year lifetime from major-brand NOS 5U4Gs.
spareribs OP Details Discussions Posts This discussion Message User 5 posts 10-28-2008 at 11:49pm Copy Comment URL Report Comment Edit Delete Wow, thanks. That seems longer than a NOS 6SN7 tube lifespan.
audiofeil Details Discussions Posts This discussion Message User 4,011 posts 10-29-2008 at 01:04am Copy Comment URL Report Comment Edit Delete >>You can probably expect a 20 year lifetime from major-brand NOS 5U4Gs.<< Perhaps. Life expectancy depends primarily on the number of thermal cycles (on/off) and hours of use. It could last 5, 10, 20 years or even more.