This is a simple tubed mixer from the 50's. The circuit does not include the power supply and has 3 inputs with independent controls. The tubes are double and the inputs are high impedance.
This configuration can be found in other articles on this site. This is from European...
This 18 V x 300 mA power supply was found in a 1969 documentation. The integrated circuit is...
This experimental 555 circuit sends signals in the medium wave band to a receiver a few meters away....