This exquisite R Type valve is smaller than the usual varieties and the grid is smaller and wound to a finer pitch. We believe that this was made in Europe after WW1.

Seen end on the electrode structure and the intact tungsten filament can be seen. Tungsten filaments of this age are extremely fragile.

The type designation is missing from the envelope but operating voltages are etched into the glass. The filament is designed to operate on 4 Volts and the anode supply can be between 60 and 100 Volts.

The balloon envelope is 48 mm in diameter and, excluding the B4 base pins, is 80 mm tall.

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This exhibit was last updated on 07 January 2007