[Doug Zielke]

Nice museum piece!
Any electronic gear you find these days containing "bottles", is worth keeping for the sake of nostalgia, if nothing else. Don't expect it to work...the electrolytic capacitors are probably well past their prime.

Heavy?
Sure...the power supply and audio output transformers would be huge by todays standards.
Beefy iron cores and copper windings.
It likely has an inverter section to convert 6-12vdc to the higher AC voltage the bottles require. More tubes and transformers.

The chassis may be made out of copper sheet as well (for heat disipation and freedom from E.M.I.).