ZM1003 Development Sample

Ronald Dekker

From a friend I got three ZM1003 “development samples.” He got them from the widow of a man who worked at Philips. On the back of the tubes is a label indicating that it is a ZM1003 development sample.

The ZM1003 is very rare. A search with Google for “ZM1003 nixie” only yielded 4 results. Dieter has on his ”tube-tester page” a scan of a 1970 VALVO (Philips) data book which lists the ZM1003 (see below). In this data book it is listed as a “Sondersymbol” (special character) tube with 1,-, and sine-wave symbols. The only other reference to the ZM1003 I found on the web was an advertisement on EBay which actually shows a few pictures of the tube (see below). That tube differs from the development samples I have in that in my samples the sine-wave symbol is not present.

The tubes I have have three symbols: 1,-, and the spiral symbol. The spiral symbol is a mystery to me. I know that there are a few other tubes who have this symbol like the ZM1263 (Mullard=Philips) and 5866STX (ITT). Does anybody have a clue what this symbol was used for? Like the ZM1001, the minus-sign of the ZM1003 is placed behind a screen that hides the glowing bottom part of the symbol. However, in the ZM1001 the minus-sign is just a stripe, where in the ZM1003 it consists of two parallel stripes. The 1 also consists of two parallel stripes.

I anybody has more information on this remarkable tube I would like to know! Please mail me at:

The following pictures are from an EBay advertisement.

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