[MrFixr55]

Hi DConat,

Generally, the lower the plate voltage the less negative the grid voltage has to be. Since the plates and screens are fed by the same voltage, the plate voltage will not be higher than the 250V that feeds the output transformer and the screens. This set looks like it is fixed bias but when you further analyze the schematic, it is cathode biased. the Candohm is between chassis ground and the return to the B+. Some folks will consider this to be a way to get C- but the voltage will vary with load, just like a cathode biased circuit will.

The grid voltage is probably a little negative than usual. The RCA Receiving Tube Manual (RC14, ca 1940 does not list the correct resistor value for cathode bias for 250V for push pull. Grid voltages are only listed for fixed bias circuits. The total Candohm resistance from B return to chassis ground is 126 Ohm. The grid return resistors are tied to the B supply center tap and ground is at the other end of the resistor. with this low a cathode resistor value, the grid voltage sounds OK to me.

There are many things that can cause low volume in a radio. The issue could be in the "amp" section(the 1st AF, 2nd AF, phase invertor, output tubes, output transformer, speaker, etc.), or in the "radio" section (RF, convertor, IF amp, detector, etc.

Due to the fact that this has a rather nice amp circuit (I don't know why there are 2 stages of AF amp before the phase invertor, but it should be pretty sensitive) with a rated 7W output in what is likely class A or AB1, I would consider adding an Aux In jack just to play mp3s through the amp. This will also tell you if the issue is in the amp or in the radio. Bhis is not difficult to do. Break the connection between cap 61and R43, R44 and C39B. Connect C61 to the common of a SPDT switch. Connect one pole to the point that C61 was disconnected from and the other pole to the aux in jack. This will allow "divide and conquer" troubleshooting, and playing big band music directly through the radio's amp will make it ROCK!

Have you checked the tubes? Do so or sub if you can. Verify that one end of the secondary of the audio transformer is grounded. Unplug the speaker and measure between ground and Pin 8 of the 2nd AF amp. It should be a very low reading, under 8 Ohm and more likely close to 2 Ohm or less (remember, impedance and resistance are two different things.

Did you recap the radio? If not, do so. A leaky cap could drive a grid too positive to amplify correctly. Check all the resistors having to do with the 1st AF ap, the 2nd AF amp and the phase invertor. A resistor in the plate or cathode circuit of the 1st, 2nd AF amps or phase invertor that is out of tolerance high will lower plate voltage, increase cathode bias, etc., all causing lower gain.

Issues in the "radio" section include tube strength, alignment issues, an open antenna coil, similar cap and resistor issues as the rest of the radio. try connecting the antenna directly to the grid cap of the RF amp and to the convertor. If much louder when connecting to the grid of the RF amp, then troubleshoot the antenna circuit. If much louder when couching the antenna lead to the grid of the convertor, then troubleshoot the RF circuit.

Hope all this helps. Let us know the outcome.