This sweetheart is the RCA designed RAK-8, a VLF TRF design with 6 tubes in a 20" near-cube weighing 74 lbs. It covers 15 to 600 Khz in 6 bands and has a 20 step sharp audio band-pass filter covering 440 to 1500 Hz. The tubes are the older 6 pin types, with 6D6s (equivalent to the 6SK7) as 1st and 2nd RF amps, and regenerative detector, and type 41s (equivalent to the 6K6) as the audio limiter and audio output amp. This receiver is very extensively shielded and filtered to prevent nearby transmitters from getting into it, and is very sensitive and selective. There is no audio gain control, the audio stage runs wide open. RF selectivity is such that the operator enjoys "single-signal" reception over its entire range. I.e., only one side of zero beat ever appears. This selectivity is arrived at by the very careful design and construction of the RF amp input and output coils only. The frequency readout is typical of the era, the early 1930s, that is, non-existent. The dial reads in 0 -100 and 0-10 and one must use a chart to tell what frequency you are on. Power requirements are extremely modest: 180 VDC at 45 mA, regulated 90 VDC at 1 mA, and 6.3 VAC or DC at 2.0 amps, yet the power supply is huge, weighing 65 lbs! Below is a blowup of the front panel nomenclature tag.
