▼ Menu

    
Extras ▼

We can find no details for the HD4. Under the blue tape the etched identification is feint but clearly HD4. The ellipse surrounding the Type designation is M-OV and the brand label is original.

The most probable identity is a B7 based version of the HD14 which has an IO base cap. This diode triode was produced by the M-OV company and the details given are for the HD14.

The classic envelope is 42 mm in diameter and, excluding the B7 base pins, is 105 mm tall.

References: ¹⁰⁴⁰ & ¹⁰⁴³. Type HD14 was first introduced in 1940. See also 1940 adverts.

Absolute Maximum Operating Conditions^¶