[Ron Ramirez]

WELL...the earlier 37-116 sets used the five individual "push pin" connectors to attach the five speaker leads to the Type W electrodynamic speaker with its audio output transformer. Later 37-116 models, and all 38-116 models, used a five-contact socket at the end of the speaker cable; there is a mating plug mounted on the speaker.

The 37-116 speaker had a 360 ohm field coil; the 38-116 speaker had a 350 ohm field (almost the same).

Model 38-116 has some circuit differences from the 37-116, most notably the use of 6L6G tubes in place of the 6B4G triodes used in Model 37-116.

The audio output transformers differ; P/N 32-7717 is used in Model 37-116; P/N 32-7751 in the 38-116.

Some Philco literature mentions Codes 125 and 126 versions of Model 37-116, using Type 6A5G output tubes instead of the 6B4G tube types. I've never seen a schematic for this version, nor have I ever seen any 37-116 sets using 6A5G tubes.

Frank, you mentioned 6A3 tubes. These were used in the 1936 Model 116X, not in the 37-116. The 6A3 has a four-pin standard base; the 6B4G is electrically identical to the 6A3, but has an octal base. Also, the speaker in Model 116X is a 10-1/2 inch U-5; the speakers in Models 37-116 and 38-116 are fourteen inch Type W units.

One more thing. There were two different 37-116 sets; a "De Luxe" model with automatic tuning (the most common version), and a "Standard Tuning" model WITHOUT the automatic tuning mechanism. The "Standard" version has a conventional dial above the concentric tuning knobs.