DD41

The Mazda DD41 is an indirectly heated double diode for AC mains receivers. Ediswan Radio specifies HF signal rectification and automatic volume control, explicitly excluding high-tension supply rectification. Heater ratings are 4 V, 0.5 A. The full type matters: data from similar-named double diodes or types with an additional amplifier section are not transferred to DD41.

Both sections have separate cathodes and are screened from each other. The internal screen has its own contact, distinct from external metallizing. This independence provides circuit flexibility. Capacitances: diode 1-earth 4 pF, diode 2-earth 4.25 pF, between diodes 0.06 pF. Measurement earth includes the remaining earthy-potential electrodes, H heater and M metallizing joined to cathode as specified in the test note, not a claimed permanent internal connection.

Mazda Octal, MO/K8B in archive data, is drawn from free base ends: 1 heater, 2 cathode 1, 3 diode 1, 4 screen, 5 diode 2, 6 metallizing, 7 cathode 2, 8 heater. Section names follow the primary sheet; some secondary tables swap the two plate-cathode pair names. Separate cathodes remain essential; metallizing pin 6 is not screen pin 4.

Sheet maximum overall length 85 mm, diameter 32 mm. Photos show metallized finishes, Mazda packaging and varying condition; specimen height 68 mm without pins does not replace overall maximum. No inverse-voltage maximum, current limit or curves are provided; secondary 175 V/5 mA do not become specifications certified by this sheet. A supposed IF frequency or use of the different HL41DD does not prove DD41 performance. Documentation: Mazda, Ediswan Radio, DD.41, A.C. Mains Double Diode, sheet 12/4, 1 May 1939. Edition date alone does not prove introduction.