DS-PEN

The Cossor D.S./PEN., indexed as DS-PEN, is a screened high-frequency pentode for mains-powered apparatus, indirectly heated at 16 V and 0.25 A. The manufacturer describes it as similar to the D.V.S./PEN. but without variable-mu characteristics. It is therefore proposed for ordinary screen-grid duties or applications not requiring volume control by varying bias. The stated similarity does not establish identical characteristics or connections across all versions.

The detector stage is explicitly mentioned: the source emphasizes the possibility of high gain with little damping of the preceding tuned circuit. Maximum plate voltage is 200 V and auxiliary-grid, or screen, voltage 100 V. At plate 200 V and screen 100 V, stated transconductance is 3 mA/V at control grid 0 V and 2.3 mA/V at −1.5 V. The graph shows plate characteristics at screen 100 V for several biases. No upper frequency limit is specified or inferred merely from the high-frequency classification.

The documentation distinguishes two base versions, an important identification detail: the seven-pin type brings the suppressor grid to a separate terminal; the five-pin type internally connects it to the cathode. The text also mentions a separate contact for the metallized coating. No numerical pinout or mechanical dimensions are provided, so the variants remain distinct without inferred pin numbers. Documentation: Cossor, Cossor D.S./PEN., catalogue page 94, technical description, data and curves. The available page has no certain publication date.