ZM 1350 Varisymbol testing challenge

This page is about testing ZM 1350 tubes for real life.
The ZM 1350 Varisybol is a planar Telefunken Nixie tube, not unlike the Panaplex and B x971 alphanumerical tubes.
Only Telefunken built those and develoment got overrun by LEDs so they became obsolete faster than TFK had imagined.
Now they are pretty popular, many nice projects can be realised with them also because of Chrisī Smartsockets allowing easy use.
(See his group at yahoo for details)
Look at this small and easy-made clock using smart sockets, still proto, no case yet on my worktable:

Orignal Datasheet leaflet (german AND english language) including pinout etc.
Orignal Telefunken contemporary circuit documentation

Our stock of ZM 1350 is still factory sealed but after some thirty years of storage they must be tested prior to shipping.
A quicktest with a portable tesla coil will filter out most of the non-performing tubes but we wanted to do better.

A former TFK employee had rescued an original Telefunken tube works nixie tester from scrap, very unfortunatively with the coding plug and the socket assembly for the ZM 1350 only and with no documentation but we are grateful to have it and now it is up and running after repair.
This instrument is pretty unique allowing both static and multiplexed test of up to five Varisymbols at once, each single digit can be checked individually, as well as all at once, currents, MPX-frequency, dutycycle, operating voltages etc. can be varied. cross electrode currents as well as normal electrode currents can be measured.

And thatīs how we test the ZM 1350 we supply:

Front view of the original Telefunken ZM1350-tester

Letīs have a look inside: finest quality electronics, stabilised voltages, precision parts...

Now letīs plug in some tubes:
Static test shows from left to right with minimum voltage for proper operation:
1.) flawless tube
2.)-4,): poisoned tubes with medium to strong poisoning.
5.) mildly poisoned tube
The tube in socket two had such a nice moving pattern that we made a small video showing it.

Multiplexed operation test. Same tube in Socket one, socket two holds the tube formerly being in socket five.
Despite the fact that the poisoned tubes "recover" after a certain time of operation we do not sell them. Ignition voltage often stays elevated, light output uneven and no one knows anything about lifetime.

This picture was taken in another moment, it shows the poisoned tube still (?) alight and the glow of the good tube just extinguishing (or firing) evenly.
We were not able to trigger the camera with the MPX signal, then we would know better...

Interesting effect: this blue discharge is inter electrode glow, not a regular test but voltages can be adjusted that way..

Only flawless tubes are being sold, you will find current pricing at our nixie tube catalog page:

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