That's a Mallory bias cell, I believe those were rated at 1.25 volts.

Thanks for the info. I seem to remember seeing something like it before in a set, but left it intact because the radio worked quite well without any attention to that component. That being said, I wonder what the plan was for service when they sold these sets. Were the customers asked to bring it in once every year or so to replace the batteries? We all know that probably never happened. This radio being serviced is a Marconi 117.

Those bias cells had such low burden upon them by virtue of their position in the circuit I don't think they were ever really thought of as consumables.

steve parr said:

Thanks for the info. I seem to remember seeing something like it before in a set, but left it intact because the radio worked quite well without any attention to that component. That being said, I wonder what the plan was for service when they sold these sets. Were the customers asked to bring it in once every year or so to replace the batteries? We all know that probably never happened. This radio being serviced is a Marconi 117.