[MrFixr55]

Hi Bridcarl

+1 on the others.  Pin 6 of the 7C6 is the AVC Diode so it is appropriate that that pin 4 of the coil connects here.  Note that it is not just pin 4 of the antenna coil that goes to this point but the secondary of the 1st IF transformer that goes to the same point, as well as a 2.2m resistor from the detector diode and a 0.1uF cap to filter the "pulsating" DC of the AVC voltage. This AVC voltage adjusts the bias on the mixer grid of the 7A8 and the grid of the 7B7 IF tube, thereby controlling the volume and preventing "blasting" when tuning a local station.

Try this:

• Take this radio and a working similar radio outside, away from the house and power lines, and compare.  With all of the CFLs, LEDs, digital electronics, transmission of electrical meter info over the power lines, etc., the environment is hostile to broadcast AM.
  

• This radio should have a loop antenna.  If it does not, you must find and install one.
  

• Unless you are in a rural area, stations should be received with the built in loop antenna.
  

Break out the VOM or DVM and verify that:

• Between pins 3 and 4 should be 1 Ohm.
  

• Between Pins 1 and 2 should be 38 Ohms.
  

• Verify wiring and polarity of the antenna coil and any other coil that was rewired.  Seems that in the pic, the wiring is incomplete and the cap should not be connected to pin 1 but to pin 2
  

• Verify that the loop antenna exists, is in circuit and verify continuity.  Ohm between Pin 6 of the 7C6 (AVC Diode) and pin 6 of the 7A8 (Mixer Grid).  This should be the same as the resistance of the loop and the secondary of the antenna coil.
  

• If you rewired the radio (likely because this vintage likely had deteriorated rubber wiring), recheck all connections of the 7A8.  Unfortunately, the schematic does not show pin numbers.  Attached below is the 7A8 page from the 1940 RCA Receiving Tube Manual version RC-14
  

7A8 fr RC-14 RCA Manual.pdf Size: 103.05 KB  Downloads: 67

Hope that this helps!