[Milsurplus] RT-21 AN/APN-21XR

[Unserviceable but Repairable]

Says 

   Mfg. Philco Corp.

Modified by Radiation Laboratory
        MIT

Mea Culpa, but it's now clear how I scrambled APX & APN.

Mike I went to 

    http://pages.cthome.net/fwc/RAD-BEAC.HTM

& it sed APN-20 & 21 were just radar beacons.  And sho nuff, RT-21
p/o ARN-7 ensemble.. Sorta makes you think ARN-7 & 21 kissing S-band
cousins.

Tnx for vector there Mike

   Marty