This is an about -30 dBu sine wave being amplified to about 0dBu by the triode section of a Sylvania 12EC8 triode/pentode "space charge" tube. The plate load is a single transistor gyrator/constant current source. Plate and heater currents are being supplied by a "China Special" boost converter module that's stepping up a 4 "C" cell battery pack.
Yick. Lots of switcher noise. The constant current source should be choking it out from the plate, so I'm guessing it's being injected from the heater to the cathode?
Needs moar filtering...