I typed out the thing about field mods and then deleted it, because I can't remember the source I got that from and I'm not actually sure I ever did see one. Do you happen to know of a source for that field mod convention?

I know that USS North Carolina and USS Washington we're refitted with SG Radar in 1942, But does anyone know if the pre-war Carriers retained the CXAM-1 or we're they also refitted with a more advanced set (And if so, when)?

Norman Friedman talks about it in his book for both SD and SJ radars, in the footnotes for his chapter on WWII.

They were refitted also.

In Norman Friedmans book "U.S. aircraft Carriers" There are a couple great pics:

On page 10, there is one of the Saratoga in May, 1942 showing her with the CXAM.

On page 11, it shows the Saragota in August 1944, and she now has the standard later radar fit of 2 air search, and SK and a backup SC-2, along with an SM height finder for fighter direction.

On page 95, there is a picture of the Yorktown in Pearl Harbor in undergoing hasty repair right before heading to her destiny at Midway, and she has a CXAM radar fitted.

Radar and other electronic fits for U.S. ships could be VERY complex and confusing as these installations / upgrades were carried out whenever and wherever they could be done.

On page 144 of the same book there is a line at the start describing Essex radar arrangements:

" The Essex-class radar arrangements were both complex and individualistic, the latter so much so that ships can often be identified in photographs by their radars. "

The text follwoing this line lists a number of radars, and different types of masts or places where the antennas were fitted, and it really seems it was like fingerprints, no two ships had exactly the same fit.

He he, it's just odd that I cannot find out what the SJ and SD stood for. I know the military loves to make acronyms out of just about anything they get their hands on. My guess was that, as someone said earlier, the "S" probably stood for the "s-band", but what the "J" and "D" part was for, well, I guess that's one of those military secrets that'll never be released. ;)

I think Zayphod, that the first two posts kind of hit on the head. the SD and SJ and SC and SV and SX were not acronyms, there were just designations applied to a radar set.