11-17-2024, 12:22 AM
I agree that it is likely a Franken radio from the manufacturer who likely got a deal on the 57, 58 and 85 tubes. The 85 is a 6.3V duo-diode triode det /1st AF tube. Strange that they are using it instead of a 75 or a 6Q7 as the 85 requires substantial (-10 to -20V) negative grid bias where the 75, 6Q7 or 6SQ7 usually have no added bias, therefore they likely got a deal on them also. The 58 is likely the IF instead of a 78 or 6K7 and the 57 is an "autodyne" convertor (1st detector) instead of the 77 or the better and more stable 6A7 or 6A8 pentagrid convertor. For these 2 2.5V 1A tubes, there is likely a dropping resistor and these tube filaments in series. Using a 0Z4 saves some filament current. According to Radiomuseum, the 0Z4 was released in 1935 and first used in 1936., so this is likely a 1936 model year radio.
The use of autodyne convertors as opposed to pentagrid convertors in car radios of the mid 30s was not uncommon. In fact, Delco used an autodyne 1st detector, using a 6C6 in Cadillac radios for the 1935 model year and a 6J7 for the 1936 model year.
The use of autodyne convertors as opposed to pentagrid convertors in car radios of the mid 30s was not uncommon. In fact, Delco used an autodyne 1st detector, using a 6C6 in Cadillac radios for the 1935 model year and a 6J7 for the 1936 model year.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
MrFixr55