tefag: L45W ; Power supply - Output power

Gentlemen,

What appears to be the major reason for the makers of the L45W model radios to use the very high voltage range for the FW rectifier - the EZ12 in lieu of the EZ11? The tube data suggests a maximum of 500 volts.

I have noticed that the later models produced in 1949/50 have the additional speakers and the UKW tuner. . . .And in some instances the rectifier has been used for theater audio systems employing output tubes requiring noticeably higher output power

Respectfully,

Robert

 

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>  reason for the makers of the L45W model radios to use the very high voltage range for the FW rectifier - the EZ12 in lieu of the EZ11?

And 100mA-125mA versus 50mA.

The EL12 alone can pull 80mA. With 5mA-20mA in the rest of the radio, the EZ11 is far too small, the EZ12 is about right.

>  rectifier has been used for theater audio systems ... higher output power

Home radio power is usually one tube in Class A (especially where tubes were taxed).

Theater systems were usually two power tubes in push-pull, and by the late 1930s often near Class B. This can be considerably more efficient.

8 Watts is a big radio. (In the US where more tubes meant higher sales-price without higher use-tax, we would go 4W-5W in one tube then go to two 6V6 tubes push-pull for 8W to 14W.)

Two such tubes in push-pull at 400V 125mA could deliver 30 Watts. (25W-40W amps were standard in theaters, even large US movie-theaters. Hard to believe in this day of 250 Watt home "media systems" and multiple 1500 Watt amps in small movie theaters.) 

Also: the radio DC supply powered the speaker field-coil, with about half the DC power as the audio output power. At least in the US, theater speaker field-coil supplies were separate from the amplifier, and usually on-stage rather than back in the projector booth with the amplifiers.

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