The National NC-33 is a general coverage single conversion 6 tube AC-DC Broadcast and HF receiver fully covering 500 KHz to 35MHz in 4 bands. It was introduced in 1948. Has adjustable BFO, electrical bandspead, standby-receive switch, built-in speaker and front-panel headphone jack. The tubes in this set are 12SA7 as oscillator-converter, 12SG7 as IF amp, 12H6 as detector, AVC, and noise limiter, 12SL7 as audio amp and BFO, 35L6 as audio output, and 35Z5 rectifier.

National NC-33 Communications Broadcast & HF Receiver Model #2150198 Ham Radio