UV199

An unusual socket or UV199 caused some bewilderment: The pin allocation appeared to deviate from the usual one.
If a tube is inserted, only the markings F+, F-, P, and G are visible. If the lcoking pin is at 12:00, then

P is found at 01:30; F+ at 04:30; G at 07:30; F- at 10:30.
Somehow it appears mirrored in the vertical axis against the usual allocation.

We had studied, made hypotheses like manufacturers error etc.

All wrong: The solution is found looking at the contact springs. They are not radially arranged as usual in such bayonet sockets, but tangentially. The contacts are rotated by 90° ccw in top view (cw in bottom view) against the terminals.

Here in top view

and in bottom view

Fazit: it is always good to take a second look!

Thanks to Peter den Boer for the socket pictures and to Alan Larsen and Alan Douglas for advice.

KoBi