When looking at my BL-210 on N/A rescources, I see that there is a difference in where the B- is located. I thought that the B+ goes to the plates (Fun with tubes). Did someone make a mistake in the drawings or is this REAL? And what is the difference between the choke being in the negative side or the positive side? Looks like the choke is connected between BOTH filter negatives. And the filter positives are connected together. Other sets show the filter between the two filter positives. Was this a mistake by the manufacturer or the circuit drawing people? And what is the advantage of either set-up? Is a negative voltage being put on the plates? Was checking on the BL-210 oscillator coil for the part no.

The schematic is drawn correctly. This sort of connection was common in 1930s radios before the much simpler cathode-resistor grid-biasing technique generally replaced it. The "trick" is that the center tap of the transformer's HV winding is not grounded to chassis but instead goes to ground via a couple of resistors. Together with the rectifier tube's action, this has the effect of lowering the CT center tap voltage BELOW ground potential- according to the schematic, about -80VDC in fact. This negative voltage can be routed to a voltage divider and then applied to the tube grids, properly biasing them slightly negative. Since the B- node is also a current source, it can be used to operate the speaker field, which it does in this case- the speaker field is not intended to be a filter reactor (choke) in this design. Of the two electrolytic caps, the one closest to the rectifier tube smooths the B+ and the other one smooths the B-.

Actually, the second electrolytic cap acts only on B+, while the second cap serves to smooth both B+ and B-.

"Actually, the second electrolytic cap acts only on B+, while the second cap serves to smooth both B+ and B-."
:
Sorry for that confusing statement: my cat is a lousy proofreader, despite having first-class keyboarding skills.

I meant to say,
Actually, the FIRST electrolytic cap acts only on B+, while the second cap serves to smooth both B+ and B-.

:"Actually, the second electrolytic cap acts only on B+, while the second cap serves to smooth both B+ and B-."
::
:Sorry for that confusing statement: my cat is a lousy proofreader, despite having first-class keyboarding skills.
:
:I meant to say,
:Actually, the FIRST electrolytic cap acts only on B+, while the second cap serves to smooth both B+ and B-.
: Thank you CV for the help, much appreciated. Joke: when did a cat learn to type? If a cat can type,why did people fail typing in high school? PLEASE don't take this seriously!