ITV Channel 11 Test Transmitter.

[Geordie McBoyne]

From the Radiomuseum, details of the 2N918 silicon NPN transistor: http://www.radiomuseum.org/tubes/tube_2n918.html

The 2N1613: http://www.radiomuseum.org/tubes/tube_2n1613.html

These are mid to late sixties transistors, helps us to put a date for the modulator.

Geordie McBoyne.