The DO60 power triode was designed for use in both public address equipment and transmitter modulators. The anode load is given as 1,500 Ohms and the output is 11 Watts in a single ended configuration. For both public address and modulation the valve would have been used in push pull and for higher power output in parallel push pull. The anode dissipation is 60 Watts.
The DA60 from M-OV is similar but the characteristics do differ even if physically they look the same. The NT18 (CV1206) specifies both DA60 and DO60.
This exhibit has a serial number of 5747.
The filament tension springs are mounted in a glass rod quite high above the anode.
One of the filament strands can be seen to be detached from the support.
The bright anode spot welded to the side supports.
The tensioning springs hold the thoriated tungsten wire filaments in a fold.
A closer look at the top of the anode showing the tensioning springs, the welds of the grid supports to the tape attached to the glass rod and the notched grid wires.
The assembly is held by supports that end in a collar tightened around the pinch stem. Very much a hand made valve.
The balloon envelope is 78 mm in diameter, and excluding the L4 base pins is 165 mm tall.
References: Data-sheet Data, & 1043. Type DO60 was first introduced in 1930. See also1930 adverts.
