[ARC5] Why the differences between the R-23 and BC453

[J Mcvey]

While dealing with a bad screen divider resistor chain in a R-23, I noticed that the low side of the of the second resistor did go to ground as it does in all of the other radios! The overall bias is different. There is an additional 3Kresistor between the second divider and ground. This makes the screen bias higher approx 140V ( assuming 240v in) and the 3k is supplying a 42V bias to the cathode of the 12SR7. 
The entire det/cw osc circuit is different in the R-23 than any of the others. ( including the other ARC series)

Anyone have a guess why they would do this?
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