Sometimes resistors were added across audio transformers in radios to reduce gain, especially low frequency response. Try your radio without it but there may be hum using modern speakers.
This can also be done when a winding is open but in that case you should find an extra capacitor from plate of 26 to grid of 45 tube.
A #26 tube will have plate voltage, pin #2, of 90-180 volts. There is a second page in Rider, about your Philco, giving some voltage and capacitor values.
Filament bypass caps values are not critical. Your radio will work without them but the original were .5 mfd according to Most Often Needed 1926-1938 Radio Diagrams.
Norm
: I am restoring a model 87 Philco radio and found what appears to be a resistor in parallel with the input side of the push-pull input transformer which doesn't show on the schematic. Can someone tell me what this is and what the voltage on the plate of the 26 tube should be? I also want to replace the dual filament bypass caps across terminals 7 & 10 of the power transformer. What would be a compatable replacement?
I would use around 22k for plate resistor but what you have is ok. Connect a .1 mfd cap from plate of the 26 to grid of a 45 tube. This should give a lot better tone quality.
Using this type of circuit won't provide gain from the transformer but overall quality should improve.
Norm
: Thanks for the tip. The radio doesn't play when I remove the resistor across the primary of the audio transformer. The primary side of the audio transformer is open but there is no capacitor from the plate of the 26 tube to the grid of the 45 tube. The voltage at the plate of the 26 tube is 79 volts with the resistor in place. Can you tell me what size resistor I should use across the primary of the audio transformer and what size capacitor I should add between the 26 & 45 tubes?