[ARC5] W5SUM Discovers SCR-274N Mystery

[David Stinson]

After all these years, I thought I had seen
everything one could see concerning SCR-274N,
but Ronnie, W5SUM, has discovered something
intriguing.  

Ronnie acquired a ham-modded BC-696.
https://goo.gl/photos/2ScqwpTXrHxNT6ZY7
Rattling-around the inside was an interesting
artifact:  an FT-243 crystal holder with its face
and internals removed, a "button" capacitor 
installed inside and a WWII-era plastic "handle"
attached:
https://goo.gl/photos/fSKufUSFbpwogPD86

Things get interesting when you turn the crystal 
holder over:
https://goo.gl/photos/4cZDarBPGCT3Pjsp9
Engraved on the back:
FOR USE IN RADIO TRANS.
 BC-457
 BC-458
 BC-459
 BC-696

Were this some kind of  "calibration crystal"
for the eye tube which a ham gutted,
one would expect the Signal Corps to order 
them with markings for the corresponding 
transmitter to avoid confusion,
not for all of them.  The polymer used for
the "handle" seems much older than something
used by a 1950s ham and its decay matches
period materials.

Ronnie is kindly sending me the transmitter and
the artifact, hoping that he and I may be able to 
tell ham mods from any possible Signal Corps mods.

Any ideas or discussion on the possible use
of this surprising bit?

TNX OM DE Dave AB5S