[AI2V]

The text for the 37-660 calls for a 5Y4 rectifier yet the schematics call for a 5X4. If the transformer can handle the extra filament amp for the 5X4, I'll go ahead and use one; otherwise I'll use the more conservative 5Y4. Which is the correct tube??

[Chuck Schwark]

5X4 is correct, as noted on page three of the 1937 Production Change Notes from Dec 15, 1936 to July 1. 1937. The schematic callout for the rectifier type is correct and the tube layout diagram and parts list are IN-correct.

[AI2V]

Thanks for the quick response, Chuck. 5X4 it is.