[Boatanchors] Tube "Scandal": 801 vs VT-25 vs VT-25A

[David Stinson]

Been working on BC-230 and BC-223 transmitters.
These use VT-25 and 801 in their RF stages respectively.

It appears that when the Military called for the VT-25,
also known as the "10Y,"  the tube makers just grabbed
the tooling for the 801 and called it "VT-25."
I base this on comparisons between a NOS 801
and a NOS VT-25.  Both have thoriated tungsten
filaments.  They operate identically in both the transmitters.
I guess the Army called "foul" or something, because
sometime during the war the VT-25A appeared.

The VT-25A is so different from the VT-25, it's not even
the same tube, IMHO.  It has an oxide-coated 
filament and longer plate for more dissipation.  
The VT-25A will deliver about 30% more power out 
than the VT-25/801.  VT-25s are commonly called 
"short plate" for the "801 in disguise" 
and "long plate" for the VT-25A.
Comparison photo with, L/R, 801, VT-25 and VT-25A:
http://home.netcom.com/~arc5/801VT25.jpg