The GU-39b is a transmitting tetrode with 8000 watt plate dissipation and a 6.3 volt 100 amp heater. Sadly one of the parallel-running heater filamens...
David Ivey leading 39b ("Sharpsburg") at the United Sacred Harp Musical Association, Mount Pisgah Primitive Baptist Church, Stroud, AL, September 9, 2007. The bass in...