I'm trying to find information about a type 24 tube for a philco model 20 radio. None of the online databases seem to list the tube although I found one that says a 24A isn't the same as a 24. Does anybody know of any data for this tube, especially substitution data? Thanks!

In most cases you can use a 24A in place of a 24. I don't know an exception. The 24A is an improved version of the 24.
MRO

Mark is correct see attached http://www.vacuumtubesinc.com/info6.html
The 24 and the 24A are interchangeable.

Also check out his article http://www.rru.com/~meo/Guitar/Tubes/usa-des.html
the 24A will heat faster and use less power to run due to filiment changes.

: Also check out his article http://www.rru.com/~meo/Guitar/Tubes/usa-des.html
:the 24A will heat faster and use less power to run due to filiment changes.

Wow! Thanks Mark and Rmeyer! I had spent days looking for this info; should have come here first. Regards and 73! Dan White KC0SWH

:: Also check out his article http://www.rru.com/~meo/Guitar/Tubes/usa-des.html
::the 24A will heat faster and use less power to run due to filiment changes.
:
:Wow! Thanks Mark and Rmeyer! I had spent days looking for this info; should have come here first. Regards and 73! Dan White KC0SWH

BTW, O. M. the UY-224 and the C-324 are the early designations for the 24/24A, and will replace it in almost all application. The UY-235 or the 251 (or the later 35/51) is the super control version of the 224, and often works well as a replacement for the 224 RF ans IF amplifier tubes, as the volume control is smoother, ant the tube is not as apt to overload on strong locals. The Super Control (or remote cut-off) tubes are not doos when used as 1st Detector, Autodune Dedector or Power Detector.