How about 1AD4 1.5V anode operation of subminiature type electron tubes

They were used for applications including hearing aids.


An interesting article is :
http://www.effectrode.com/signal-tubes/subminiature-tubes/


Or:
https://www.diystompboxes.com/smfforum/index.php?topic=93761.0
Showing the Russian 1J24b operating with Vh=1.2V, 13mA
This so low consumption reminds of electrometer tubes. See Pleiades V1 operating with just an AAA 1.2V battery.


More information on Russian subminiature electron tubes:
https://www.radiomuseum.org/forum/russian_subminiature_tubes.html?thread_id=200277
Schematic and and an electron tube (1SH24B) with suppressor grid not connected to cathode, control grid connected to anode just like the space charge tetrode 12K5 used on Pleiades Electra II):
https://pics.kanojo.de/Preamp1sh24.gif


Also this:
http://www.radicalvalves.com/russian/russian-rod-pentodes-1/


Also this about the 1J17B:
http://www.diyaudio.com/forums/tubes-valves/191183-experience-1j17b-tube.html


The heater requirements of 1DS4 are higher but just 1.2V at 100mA.


Would electron tubes such as 1AD4 (DF62) or others like the above ones operate with just 1.2V at the anode with Pleiades bias?


It may be tried on the Pleiades V6 circuit with smaller values of Rag. (Always use a fuse in series with a battery for safety)





See also the Pleiades V1 operating with an electrometer electron tube and just one AAA 1.2V battery:
http://euroelectron.blogspot.com/2018/07/a-one-tube-microphone-headamp-operating.html