That large tube is a UV-876 which is a constant current regulator. Back then, line voltage varied all over the place causing the volume to go up and down drastically as the voltage changed. I have a regular Radiola 28 with the separate 104 speaker which electrically is pretty much the same and they are very sensitive sets.
FR
:::Hi all..I just had to share this with all of you. A few years ago I bought a radio from the son of the original owner for $200.00. It was R.C.A Radiola 32. Massive radio..must weigh over 300lbs. At the time I just though it was a "neat looking radio" ...untill I started to do some research. I was unaware that ony 3186 of these were made in 1928 and was sold for $928.00..It is a R.C.A Radiola 28 chassie, 104 speaker, and antena all rolled into a deluxe cabinet.
:::I just got done restoring the caps and the dam thing works like new....What a joy!!!! OOOPS also this set has an early amp that uses these tubes 2 281s
::1 210 and a large Glass envelope tube to break down wall current. Reciever ueses 7 Ux199 tubes
:
:That large tube is a UV-876 which is a constant current regulator. Back then, line voltage varied all over the place causing the volume to go up and down drastically as the voltage changed. I have a regular Radiola 28 with the separate 104 speaker which electrically is pretty much the same and they are very sensitive sets.
:
:FR