[R-390] gold-plated tubes

[Wim Penders]

Philips Holland and their subsidary Mullard in England made tubes with 
gold-plated pins.
They were Special Quality tubes with a guaranteed life time of 20.000 
hours, much more than the standard tube.
The other advantage was their very close specs.
I for one prefer them much over the "normal" tubes, because they are 
almost undestructable.
They were used in all special measurement instruments of the time overhere.

FWIW
73,  Wim PA0PGA