Philco radio cap problem

[radio nut]

Well, I retried my set and I am back to square one. Same problem again, blew my last 1lb4 output tube( too much heater voltage). The cleaner I used last night was an older slow dry type. I even took a hair dryer to it today to make sure it was ready to go.Well, I had bought the last 1lb4 tube that Fair Radio here in town had so I will try to go there and search the "back stock" to see if I can come up with another. In the meantime I am going to unsolder one end of every cap in the set and use my heathkit to see if maybe that cleaner although it was not the lubricating type, being it was slow drying did soak into a cap and short it out.The one thing I would really like to ask someone from Philco is why was this set not a "clean "series string as far as heaters went.Why all the side taps into B+ lines and junctions to IF secondaries?I was thinking that my overvolting issue was from a leaky cap tapped into a B+ line.I guess I will find out soon(not soon enough)!

[rollei35guy]

Sorry to hear that. How did it go out? Was it operating for a wile? Is that cap still getting hot?

Originally Posted by radio nut

The one thing I would really like to ask someone from Philco is why was this set not a "clean "series string as far as heaters went.Why all the side taps into B+ lines and junctions to IF secondaries?I was thinking that my overvolting issue was from a leaky cap tapped into a B+ line.I guess I will find out soon(not soon enough)!

I was puzzled by the complexity of the heater string too until I realized it's a directly heated cathode. In other words the heater and the cathode is the same element. So you have both the heater and signal on the same element.

You might well be right about the caps shorting out either from cleaner or age. It's possible that they are good initially when you turn on the set but break down after being at working voltage.

If you can figure out what the filament resistance should be on the 1lb4, you could wire in a resistor of similar value as a dummy filament so you could trace out the problem with out burning out another 1lb4. On the other hand you might burn out something else.