and [J.G.] has put a few of them to work in this battery-powered audio tube amplifier. The key to the build is the Russian-made 2SH27L battery tubes which are originally designed in Germany for ...

[Mikremk] demonstrates this with a simple but effective amplifier using a PCL82 triode-pentode. It’s a conventional tube amplifier circuit in which the triode is a preamplifier for the pentode ...

Testing the replacements in a familiar amp and setup can help determine ... a solid-state replacement for popular power vacuum tubes. It can replace a range of power tubes, including 6550, KT66 ...