[Penthode]

2.25 MHz sound spacing was used in 1933-34 not for the 1936 343 line and 441 line broadcast tests from July 1936. It is described in the volume 1
Television.

Do not confuse this with the earlier 240 tests described.

Goldsmith described that RCA engineers arrived at a 6MHz channel without the details of the video-aural carrier frequency spacing. You have to dig a bit to find the information.

But think logically about this: they identify the carrier frequencies which would fit nicely in the 44MHz to 50MHz channel. The RCA Volume 1 Television explicitly lists the sound carrier as 49.75MHz and the video carrier at 46.5MHz. The difference.is 3.25MHz.

The video aural carrier spacing could not be moved to 4.5MHz until after the modification from double sideband to vestigial sideband which RCA made immediately before the 1939 World's Fair. Your documentation identifying the change must be from 1939 not 1937..
I know this is correct. I encourage you to look for it. If you require further evidence I will dig it out for you.