General Electric Y1938 
Written by AnubisTTP on 2006-11-05  


Devices included in this entry:

General Electric Y1938 (nine pin base)

General Electric Y4102 (overflow indicator, nine pin base)
General Electric blue-dipped Y1938 (nine pin base; pictured in thumbnail)
General Electric prototype Y1938 (nine pin base)

An early VFD tube, the General Electric Y1938 is an attractive display in a classic nine pin envelope. This device is a bit higher quality piece of construction than the Tung-Sol Digivac VFDs shown elsewhere on this page--Y1938 tubes have more evenly lit digits and higher build quality overall. Some 1938s have holes where a decimal point would have appeared, while others do not. Some units also have a thick blue coating over the glass, to improve the color of the digits. It is unknown whether this blue coating was applied by GE or by a secondary manufacturer. General Electric also manufactured a companion overflow indicator for the Y1938; the Y4102. This overflow indicator tube has separate tiles to display a plus or minus symbol, in addition to the '1' segments and a decimal point. Prototypes of the Y1938 have a radically different internal construction, incorporating a printed VFD material on a ceramic substrate instead of the separate tiles used in production VFDs. It is unknown why this apparently superior manufacturing process was abandoned in production devices.

Of important note to the modern day hobbyist is that this tube lacks a control grid, a refinement not added to VFDs until after this tube was manufactured. With no control grid, this display can not be multiplexed

General Electric Y1938 Datasheet (PDF, 136kb)


General Electric Y1938 vacuum florescent(VFD) tube.

Some Y1938 displays were dipped in blue coating, popular among nixie tube hobbyists for its distinctive appearance.

Y4102 overflow indicator tube, normal operation.

Early prototypes of this tube used a wholly different internal construction, involving an complex ceramic substrate with printed or stamped VFD phosphor material.

Test fixture for Y1938 displays and other VFD tubes.

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