[MrFixr55]

Hi dconant.

I have not worked on the 27 but have worked on the somewhat similar Gloritone 26 for a friend.  These are TRF sets with 2 stages of RF amplification, using 24A tetrodes, and a "biased" detector.   This is the same as the Philco 20 and Gloritone 26 except that the Philco 20 and Gloritone 26 use a 24A as the biased detector while the 27 uses a 27 triode.  The 20 uses an extra stage of audio amplification and a push-pull output.

Yes, the Gloritone 27s have an upside down chassis.

The wiring of the volume control may look weird to those working on later model radios (Why is the wiper grounded?) but analyzing the circuit makes sense.    In the early Non-AVC TRF sets, volume was controlled by one of several techniques:

• Shunting the antenna input. (This was done on the early TRF RCA Radiolas.)
  
• Varying cathode bias on the RF and / or IF amplifiers. (This was done on the early Gloritone 27, RCA Radiola 60 and 80, the R7 and other early RCA sets.)
  
• Doing both with ganged control elements.  (This was done in the Philco 20.)
  
• Controlling screen voltages on tetrode RF Amps.
  

The control on the late Gloritone 27 and the Gloritone 26 does both, adding cathode bias and shunting the antenna input, using only one control with only one element.  As the control is turned towards minimum volume, the antenna terminal is shunted by low resistance and cathode bias of the 2 RF amp stages is increased, lowering the gain of the RF Amps.  As the volume control is turned to increase volume, bias is lowered, increasing RF Amp gain and the shunt resistance is increased to a level much higher than the resistance of the antenna coil.  This is why the center tap is grounded.

It is always best to attempt to rewire a radio in the same manner as originally wired.  However, for this radio, going from socket to socket for the filament windings is OK to do.  Yes, all filaments except the rectifier are powered by the same 2.5VAC secondary.  The center tap of this secondary is grounded.  Use sufficiently heavy wire, as total filament load is approximately 6.5A.  Use a minimum of 18 gauge solid or 16 gauge stranded wire, as a twisted pair.  I would start at the '45 output tube but follow the original routing.

I have not used motor caps but those suggesting them are experts who have used them successfully.

Hope this all helps.