The 41MDG mixer from Cossor was designed between 1932 and 1934. The mixer is an essential component in the superhet receiver. The signal is applied to one grid and a local oscillator voltage applied to the outer grid. The two frequencies multiply in the non-linear transfer characteristic of the valve and both sum and differences will be present in the anode circuit. The wanted frequency will be where the anode circuit is tuned and then further amplicification at the Intermediate Frequency can take place before the signal is demodulated in the detector.

In addition to the B5 base there is an extra terminal on the side of the base.

It is indirectly heated and within the envelope can be seen the single hairpin heater within the flattened cathode tube. The grids are not close to the cathode and are wound from bright wire. The anode is a bright box with the sides replaced with a wire gauze.

The balloon envelope is 48 mm in diameter and, excluding the B5 base pins is 104 mm tall.

 
Absolute Maximum Operating Conditions

Tetrode	Vh	Ah	Va	ra	gm
	4.0	1.0	200	27,000	0.25

This exhibit was last updated on 02 December 2007