Philco 39-30 radio

[TUD1]

The capacitor blocks have been restuffed. While I was looking in there, I found a mysterious loose/broken wire. It leads to one of the coils. Could that be a problem?

[dieseljeep]

Originally Posted by TUD1

The capacitor blocks have been restuffed. While I was looking in there, I found a mysterious loose/broken wire. It leads to one of the coils. Could that be a problem?

The leads you're referring to, might be item 3 on the schematic. It's just 2 wires twisted together, forming a capacitance. Usually known as a gimmick.
The circuit used is a regenerative superhet and are a little tricky to setup.

[TUD1]

We have been discussing this radio on Philcoradio.com and have come to the conclusion that I need to check the antenna coil and oscillator coil with an ohmeter. I will also be getting rid of those dogbone resistors.

[rca2000]

Looking at the bottom view of that chassis I see something BADLY wrong I think--I am surprised NO ONE ELSE saw it. (assuming this is the chassis for the cathedral radio).

the tube behind the power tranny, looks like a 42 does NOT seem to have ANYTHING connected to it !! a 42 is a pentode and should have at least 5-6 connections MINIMUM--and I see at most TWO. This WOULD give a no sound problem.

Not sure WHY someone unhooked the output tube--but it looks like they did.

[TUD1]

Here is the 42 socket.

[rca2000]

i guess that must be the 80 behind the tranny then.

I would see how my B+ looks before going much farther. Not sure exactly...but on a cold chassis like this it should be at LEAST 225, likely over 250--from the rect cathode to the filter caps. If it is that or higher--the B+ is ok.

[TUD1]

People keep telling me about B+, but I have yet to find out what it is.

[stusnyder]

Best to check the tubes, then get a schematic and start shecking voltages.

[Electronic M]

The average tube set has two or more (lets ignore cases of more for now) power sources. The A supply is the heater voltage for the signal tubes, and the B supply is the supply voltage for the plates etc. (what the set uses to allow the tubes or transistors to process the signals). The B- terminal is often tied to chassis ground so when you measure the B+ you are measuring the B supply usually with referance to the chassis.

The letters harken from the 20's when all radios were powered by batteries. Some sets had a C- supply for the grids, but we got smart and found ways to make the B supply run the grids too. Sets with multiple heater supplies were not given any special names for the branches of the A supply, and sets that used resistive voltage dividers for multiple B+ voltages simply called the different B+ lines by their voltage.

[old_coot88]

Originally Posted by stusnyder

Best to check the tubes, then get a schematic and start shecking voltages.

Factory schematic and parts layout is in one of the linkys in post# 15.