[Raleigh]

Johnny,

Typical diagnostic procedure is to identify the last point you can get a signal through to the speaker and then test the stage before it.

You've made progress by showing that you get a tone from the speaker when putting a modulated 455 KHz signal into the grid of the 2nd IF tube. You've proved the radio works from that point forward. The plate of the 1st IF is the input to the 2nd IF transformer, so if you get a tone from there to the speaker, you've proved that the 2nd IF transformer (#34) works and that the radio works from that point forward.

But If you get no tone when putting the 455 KHz modulated signal on the 1st IF grid, logic tells you that the 1st IF stage is not working for some unknown reason. You first must find the fault in the 1st IF stage. Putting a signal into the antenna terminal will not get past the fault in the 1st IF stage, so that is not worth trying until you repair the 1st IF stage and verify that it works by putting a signal on the 1st IF grid.

Here are some of the obvious things to try.

1) Connect your signal generator again to the 2nd IF tube. Verify that you get a tone as before. Leave the generator connected and swap the two IF tubes. If you get no tone, then the tube now in the 2nd IF socket is probably bad. If you get a tone, then the tube is good and the fault lies elsewhere in the 1st IF stage.

2) Check for 180 Volts DC at the plate of the 1st IF tube. I assume you have done this.

3) Check for 100 Volts DC at pin 3 of the 1st IF tube.

4) Check that the filament is heating properly. (Tube should get a little bit warm after a while.) Or you could remove the tube and measure across the socket pins 1 and 8. You should get around 6 volts AC with the tube removed. Another way is to leave the tube in place and measure across those same pins. You should get a small AC voltage, maybe less than 1 volt AC, across the filament. If it is near 6 VAC then the filament is not drawing current, either because it is burned out inside the tube or because it is not making contact with the socket.)

5) With the radio OFF check the continuity between the 1st IF tube pin 7 (cathode) and ground. Should be close to zero ohms.

6) With the radio OFF check the continuity between the first IF socket pin 6 and the blue wire of the 1st IF transformer part #32. (Blue wire connects to resistor #33 and bypass cap #29). Should be 11.5 Ohms. Then measure from pin 6 to ground. I can't tell exactly what you should get because my schematic is blurry, but I think it should be around 3.75 Mega-ohm.

Let me know what you find. Again, if you can't hear a tone with the signal generator putting a modulated 455 KHz signal on the 1st IF grid, then no tests on the antenna or earlier stages are going to tell you anything.