This receiver was found in a Popular Electronics from the 90's. Its different configuration shows a tuning circuit after the tube that works as an aperiodic amplifier. Observe supply voltages.
This tube circuit is from an 80's documentation. The filter is of the selective type and the...
This circuit is from a 1969 RE Experimenters Handbook. The circuit is powered by the voltage of the...
With an 18 V input, this regulator was found in Philips documentation from the 60's. The...