warren i just read your message about the fiber washers under the filter can.where is the b- connection that i connect to i dont know much about b- there are 5y3gt in radio and should be 5z4 is 5y3 allright to use.
appreciate very much for message bobby

:warren i just read your message about the fiber washers under the filter can.where is the b- connection that i connect to i dont know much about b- there are 5y3gt in radio and should be 5z4 is 5y3 allright to use.
: appreciate very much for message bobby
:
B- is the center tap of the power transformer's HV winding. It is at a negative DC voltage with respect to the chassis ground and is used to set tube grid biases. There should be a wire that runs from the transformer HV center tap to the metal case of the insulated capacitor.

5Y3 can usually sub for a 5Z4. The Z4 is a heater-type tube while the Y3 has no cathode sleeve. So, their power-on characteristics will differ (the Y3 will produce voltage faster than the Z4 on startup), which could lead to a voltage surge on B+ (since the other tubes, being heater-type units, won't draw current until their own cathodes have been warmed up sufficiently. This brief no-load condition may cause an overvoltage condition on all caps hanging on the B+ line. After warmup, the two tube types are pretty much the same (same filament current rating).

The outside ring of the filter can is the B- line. It is isolated from the chassis by that fiber mount washer. You can still use the negative connections on this ring as your negative end filter capacitors connections.