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The DY87 is a television EHT rectifier introduced in 1956 and this exhibit has the Pinnacle name. It was designed to have its heater supply produced by an overwind on the line output transformer. The 18,000 Volt rating places this as a rectifier for medium sized monochrome televisions. We also have the EY87 with a 6.3 Volt heater.

Electrically the DY87 is identical to the DY86. The DY87 has the glass treated with silicone to improve insulation in humid environments.

This exhibit looks to be unused whereas DY87 clearly shows signs of use in the darkened logo and discolouration of the glass. Both are foreign made imports to the UK.

The anode reaches down almost the the level of the cathode screen.

The anode has a closed top and a rounded base. The latter is probably to reduce the risk of flashover.

The thin glass tube envelope is 21 mm in diameter, and excluding the B9A base pins is 65 mm tall.

References: Data-sheet & ¹⁰⁴⁰. Type DY87 was first introduced in 1955. See also 1955 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.