The 1H5GT is a dry battery diode triode for receiver use. The 1LH4 is the same valve but on a B8B base. In a TRF receiver the diode would provide AM signal demodulation and the high μ triode would be the first audio voltage amplifier.
This exhibit is an import and the glass has the word Foreign above the Dario name.
With clear glass the inner structure is very easy to see. The lower filament support is connected by tape to the diode anode screen. The diode anode is the vertical rod to the right of the filament.
The top mica has fingers touching the inner of the envelope on two sides only.
The wide glass tube envelope is 29 mm in diameter, and excluding the IO base pins is 67 mm tall.
References: Data-sheet, 1040 & 1043. Type 1H5GT was first introduced in 1940. See also1940 adverts.
