The radio is a Stromberg Carlson Canadian model 761, similar to the American 1101 I think. It has the 6 octal tubes with a 35Z5 and a 35L6.
The chassis is laid out with a bare B- wire running from one end to the other. There is a 25 mfd 600 v electrolytic capacitor between the B- and the chassis. it appears to be original, and I have an old schematic that shows it.
I checked my SC Model 561, same chassis, same tubes, and it has a .01 mfd cap in that position. Why would they feel this large expensive cap was needed? The radio isn't working yet, but I'm wondering if I should use a more conventional value here?

:Just a link for reference from RCC courtesy of Tom Bavis.Would that be C29?

http://www.audiophool.cjb.net/Schem_R/Stromberg_752_761.pdf

::Just a link for reference from RCC courtesy of Tom Bavis.Would that be C29?
:
:http://www.audiophool.cjb.net/Schem_R/Stromberg_752_761.pdf
:
:
:

Yes, that is it, C29 on page 3, 25 mfd.
When I first saw it, I thought it was a filter cap, but it connects B- to the chassis, with its negative end to the chassis. I'm just curious why a smaller cap wasn't used. I have 2 other Strombergs of similar vintage that use .01 or .05 mfd caps to do that job. They are actually 6 tube radios, good performers.

Could be the 25 cycle vs 60 cycle chassis.

:Could be the 25 cycle vs 60 cycle chassis.
:

The label says Cycles - DC to 60.
I've put a 22 mfd electrolytic in place of the big old waxed paper cap. I'm not going to try to reinvent the radio to save a dollar or two.
It's interesting to see the circuits evolving after the war when production started taking off. My younger Stromberg 1500 had the selenium rectifier, which I've bypassed, and 5 mini tubes.

::Could be the 25 cycle vs 60 cycle chassis.
::
:
:The label says Cycles - DC to 60.
:I've put a 22 mfd electrolytic in place of the big old waxed paper cap. I'm not going to try to reinvent the radio to save a dollar or two.
:It's interesting to see the circuits evolving after the war when production started taking off. My younger Stromberg 1500 had the selenium rectifier, which I've bypassed, and 5 mini tubes.

I have seen a large electrolytic cap like this on the B- leg to chassis on otther radios. It is for added hum/noise filtering.
The chassis may be positive in respect to the B- leg which would mean that the '+' end of the cap should go to chassis and the '-' end to the B- bus.
Looking at the schematic for your 761, I don't think this would apply. The negative voltages needed for AVC and bias wouldn't be that large.
:

:Could be the 25 cycle vs 60 cycle chassis.
:
Interesting point Warren and since a lot of Canadian radios fed of the 25 cycle Niagra grid that might explain it.

Thanks for posting that.

Ken