Sylvania 12AU7 12AU7A NOS-Testing Copper Support Rods Triple 3 Mica Vacuum Tube For Your Bottlehead Univalve T15 T03 These three Ken-Rad 1A7GT tubes

These three Ken-Rad 1A7GT tubes tested to spec on our Paul Hart-calibrated TV-7/U

black plates and Micanol bases

This matched pair of RCA-MANUFACTURED 5Z4 rectifier tubes were tested on our Paul Hart-calibrated TV7/U for shorts

This Tung-Sol 9BR7 tube tested to spec on our Paul Hart-calibrated TV7/U

There was no gas and it tested 2170 micromhos with a plate current draw of 25

Sylvania 12AU7 12AU7A NOS-Testing Copper Support Rods Triple 3 Mica Vacuum Tube For Your Bottlehead Univalve T15 T03 These three Ken-Rad 1A7GT tubesThis Sylvania triple mica 12AU7A ECC82 dual triode was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. Transconductance measured 73 79 where new nominal is 50 50. This tube has two additional vertical support rods; an additional mica spacer for low microphonics; crenelated, round mica spacers and excellent flashing. I have played it in my Bottlehead Crack headphone amplifier and it sounds