15.5mm symbol tube manufactured by Siemens

The ZM1021 is a clear glass symbol tube manufactured by Siemens. It was used in measurement devices along with the numeric ZM1020 tube. There is also a red coated version, the ZM1021
Brand / Manfacturer Siemens
Same Types
Likely Tyes
Symbol height in mm 15.5
Characters / Symbols +,-,%,Ω,V,A,sinewave
Decimal point none
Base / Socket B13B
Starting Voltage (typ) 170 V
Maintaining Voltage (typ) 145 V
Current per Segment 2mA
Reccomend Resistor 12.5kOhm = 2mA


See ZM1023 Mullard for images of the digits