Experimental series

Up ………. PL

It has a transistor in a larger housing, it has no visible markings and I have not found any information about it. It is possible that the label has been obliterated, and what is left does not give any chance of recognition. So no bigger series comes from. It is possible that it was produced at the National Institute of Telecommunications, but no evidence is available.

The transistor in a smaller housing has the markings TW 108. I suspect, but only suspect, based on retrodekan.eu, that it is a TW1 transistor developed at the Department of Electronics IPPT PAN, with a large participation of doc. Tadeusz Janicki, and a trial series was made at the National Institute of Telecommunications. the number 108 suggests that the transistor is from a short series. The datasheet of TC transistors indicates that the basis for their development was the TW transistor.  I haven’t found another photo of the TW1 transistor yet.